COMMUNICATION | doi:10.20944/preprints201805.0333.v1
Subject: Environmental And Earth Sciences, Atmospheric Science And Meteorology Keywords: atmospheric river; avalanche; debris flow; flooding; snow level; typhoon
Online: 24 May 2018 (05:53:39 CEST)
On 5-7 April 2018 a landfalling atmospheric river resulted in widespread heavy precipitation in the Sierra Nevada of California and Nevada. Observed snow levels during this event were among the highest snow levels recorded since observations began in 2002 and exceeded 2.75 km for 31 hours in the northern Sierra Nevada and 3.75 km for 12 hours in the southern Sierra Nevada. The anomalously high snow levels and over 80 mm of precipitation caused flooding, debris flows, and wet snow avalanches in the upper elevations of the Sierra Nevada. The origin of this atmospheric river was super typhoon Jelawat, whose moisture remnants were entrained and maintained by an extratropical cyclone in the northeast Pacific. This event was notable due to its April occurrence, as six other typhoon remnants that caused heavy precipitation with high snow levels (mean = 2.92 km) in the northern Sierra Nevada all occurred during October.
ARTICLE | doi:10.20944/preprints202107.0419.v1
Subject: Environmental And Earth Sciences, Atmospheric Science And Meteorology Keywords: Urban Eco-Sustainable Index; Watershed Sustainability Index; Ecohydrology; River Basin Management; Water security; Participation
Online: 19 July 2021 (15:22:17 CEST)
The Urban Eco-Sustainable Index for Upscaling Water Security at Catchment Level in Langat River, Malaysia has developed by using the Modified Watershed Sustainability Index or MicroWSI (MWSI), which was based on the Participation, Design and Management Components. The study has successfully applied spatial and social dimensions on ecohydrology of the selected Langat River reach for stormwater management, natural ecosystems health and quality of life. The planning and public participation aspects of the study have evaluated the surrounding neighborhood area of Langat. The conceptual design of rehabilitation works implementation related to Urban Stormwater Management Manual for Malaysia (MSMA) Stormwater Management Ecohydrology (SME) within the study area has been developed with four components of MSMA-SME to be implemented in the study area i.e Bioretention System, Porous Pavement System, Constructed Wetland and Slope Protection Works. These components were proposed to be applied in the development of Langat Riverfront Community Park (LRCP) which has taken into account the components of Design, Management and Participation of Community and Stakeholders in Langat River Basin, Malaysia. This study analyzed the MWSI for the Upscaling of MSMA Ecohydrology at Catchment Level of Langat River and has found the medium level of sustainability for the level of participation, proposed design, and management. Thus, there is a need to increase the level of readiness in the community and stakeholder participation in the Langat River towards sustainability of river conservation and rehabilitation programmes in this basin.
ARTICLE | doi:10.20944/preprints202308.2031.v1
Subject: Environmental And Earth Sciences, Water Science And Technology Keywords: Euphrates River; NDWI index; Satellite monitoring; Hydrological changes; Water level dynamics
Online: 30 August 2023 (08:25:31 CEST)
The construction of 22 dams on the Euphrates has reduced the flow of this river, changed the hydrology and destroyed the ecosystem. In order to understand the effect of extreme management on water, 4 coastal points from the Euphrates catchment area were selected to investigate the dynamics of the water level. Using the Cadmium method, the radius of each point was calculated to be 140 meters to study the NDWI index and satellite monitoring. 546 Landsat 8 OLI/TIRS satellite images from 2013 to 2022 were used. The analysis showed that the water level of the Euphrates in the fourth coordinate is directly related to the data of the first and third coordinates and the dynamics of the water level in the fourth coordinate is 3.6 to 4.2 percent of the first coordinate and another 5.2 to 5.9 percent is affected by the third coordinate. Is. Also, the data from August 2013 to 2022 were analyzed. The results showed that the correlation coefficients of the data related to the first coordinates are related to the third and fourth coordinates. It was proved that fluctuations in the first coordinate led to 27% change in the third coordinate in the months of August. Also, the changes in the first point caused 18-19.8% change in the dynamic level of water in the fourth point, and 22.5% of the changes in the water level in the fourth coordinate were affected by the third point.
ARTICLE | doi:10.20944/preprints202308.0129.v1
Subject: Environmental And Earth Sciences, Atmospheric Science And Meteorology Keywords: SMAP model; CMIP5; Parnaíba river basin; São Francisco river basin; Iguaçu river basin; Uruguay river basin.
Online: 2 August 2023 (08:02:16 CEST)
Brazil has a large availability of natural resources and its economy was historically built around their exploitation. Changes in climate trends are already causing several environmental impacts, which affect the economic and social organization of the country. Impacts linked to the hydrological cycle are particularly concerning since water resources are used for electricity production, representing approximately 65% of the Brazilian electricity matrix. This study, therefore, aims to evaluate the hydroclimatic extreme trends of river basins located in the Northeast and South regions of the country. For this purpose, we carried out a flow analysis from 2020 to 2100, considering the precipitation data from the BCC CSM1-1, CCSM4, MIROC5, and NorESM1-M models presented in the Fifth Assessment Report of the Intergovernmental Panel on Climate Change - IPCC. We used the SMAP rainfall-runoff model to obtain future flow projections for the RCP4.5 and RCP8.5 scenarios. As a result, we observed a trend toward water loss and intensification of extreme events, with an increase in variability in both scenarios. We also noted that these climate models have difficulty reproducing the natural variability of southern basins, as the simplification of atmospheric phenomena parameterization prevents them from correctly projecting the precipitation.
ARTICLE | doi:10.20944/preprints202301.0561.v2
Subject: Computer Science And Mathematics, Information Systems Keywords: Sensors; data-set; Machine learning; river floods; river level
Online: 1 February 2023 (03:54:50 CET)
Reliable and accurate flood prediction is a challenging task in poorly gauged basins due to data scarcity. Data is an essential component of any AI/ML model today, and the performance of such models hugely depends on the availability of sufficient amount of trusted, representative data. However, unlike a few well-studied rivers, most of the rivers in developing countries are still insufficiently monitored, which significantly hinges the design and development of advanced flood prediction models and early warning systems. This paper presents a multi-modal, sensor-based and near-real time river monitoring system to produce a multi-feature data set for the Kikuletwa river in Northern Tanzania, an area that heavily suffers from frequent floods. Our deployed system, which gather information about river depth levels and weather at several locations, aims at widening the ground truth of the river characteristics and eventually improve the accuracy of flood predictions. We provide details on the monitoring system used to gather the data as well as report on the methodology and the nature of the data. Finally, we present the relevance of the data set in the context of flood prediction, discussing the most suitable AI/ML-based forecasting approaches, while also highlighting some applications of the data set beyond flood warning systems.
ARTICLE | doi:10.20944/preprints202206.0173.v1
Subject: Business, Economics And Management, Economics Keywords: Tarim river; ecological service function value; river ecosystem; evaluation indicators
Online: 13 June 2022 (09:33:56 CEST)
The estimation of ecological service system value of water resources in Tarim river basin is of great significance for resource allocation management and ecological protection. However, there is still no unified and complete evaluation method for ecological service system value of inland river in China. Based on the perspective of the whole value chain, the study classifies its ecological service functions, and divides 11 sub-categories into 4 categories (supply, regulation, culture and support) as evaluation indicators to carry out quantitative evaluation. The results showed that the total value of ecological service system in Tarim river basin in 2018 was 4156.5247×108 Yuan, and the value of regulating function, cultural function, supporting function and supply function were successively from high to low, which were as follows: 2565.6825×108 Yuan, 1009.5471×108 Yuan, 884.0770×108 Yuan, 20.3350×108 Yuan, among which the value of regulation function is dominant.
ARTICLE | doi:10.20944/preprints201902.0120.v1
Subject: Environmental And Earth Sciences, Environmental Science Keywords: DHABSIM; iRIC suite; numerical modelling; Po River; River2D; river habitat
Online: 13 February 2019 (15:36:43 CET)
Numerical modelling is becoming a major tool for supporting environmental studies at different scales, thanks to the capability of up-to-date codes in reproducing the natural behaviour in a quite reliable manner. In evaluating the habitat diversity of anthropized rivers, however, many issues are rising because of the intrinsic complexity of the processes involved. Using a reach of the Po River in Italy as a case study, the present works aims to provide an estimate of the changes of the Eco-Environmental Diversity as a response to different constant flow discharges. The goals are achieved by means of two solvers of the iRIC suite, applied in sequence to firstly simulate the fluvial hydrodynamics and subsequently provide an estimate of the habitat conditions. Despite the simplifications intrinsically present in the models and the ones introduced for practical purposes, the results pointed out that the reduction of the flow discharge recently observed can threat the overall biological status of the river. Because of the modelling uncertainties, on the other side, these preliminary outcomes show the need for more research, both in terms of data acquisition and numerical schematization, for adequately evaluate the effects of transient hydrology on the river ecosystems. Moreover, additional field surveys are necessary to calibrate and validate the used model for having sufficiently reliable estimates.
ARTICLE | doi:10.20944/preprints201907.0054.v1
Subject: Biology And Life Sciences, Animal Science, Veterinary Science And Zoology Keywords: Eurasian otter; Lutra lutra; Italian population; otter; Italy; Pollino; river; mustelid; Lao river; Pollino National Park; Mercure-Lao River
Online: 3 July 2019 (09:13:28 CEST)
Here we report recent evidence of the presence of Eurasian otter (Lutra lutra) in the Mercure-Lao River valley, an area of great ecological interest situated in South Italy for which the last otter reports referred to spraints collected in 2002. This work contains information and a selection of photographs of otter footprints and spraints found from October 2005 to January 2019, and photographs of both a cub and an adult otter from the Mercure-Lao River area.
ARTICLE | doi:10.20944/preprints202306.0284.v1
Subject: Environmental And Earth Sciences, Water Science And Technology Keywords: River Planform; River Reaches; Automatic Identification; Geomorphics Elements and Units; Biobío Basin
Online: 5 June 2023 (09:02:24 CEST)
This paper addresses the issue of the automatic identification of river reaches and their planform type, given the (observed) set of geomorphic elements and units. It introduces further advances with respect to the original proposal by Nardini and Brierley. And it explores explicitly the ability of the algorithm and associated tools to work properly on significantly different rivers while adopting a given same parametrization. This was indeed an envisaged ability speculated as a challenging conclusion of the previous work. The Duqueco, Laja and Biobío rivers (Chile) are analyzed for this purpose. The conclusion is definitely positive, what opens future promising application horizons.
ARTICLE | doi:10.20944/preprints201610.0023.v1
Subject: Environmental And Earth Sciences, Geophysics And Geology Keywords: climate change; water cycle; downscaling; hydrological model; Yangtze River; Yellow River; Tibetan Plateau
Online: 8 October 2016 (11:29:05 CEST)
Climate change is a global issue that draws widespread attention from the international society. As an important component of the climate system, the water cycle is directly affected by climate change. Thus, it is very important to study the influences of climate change on the basin water cycle with respect to maintenance of healthy rivers, sustainable use of water resources, and sustainable socioeconomic development in the basin. In this study, by assessing the suitability of multiple General Circulation Models (GCMs) recommended by the Intergovernmental Panel on Climate Change, Statistical Downscaling Model (SDSM) and Automated Statistical Downscaling model (ASD) were used to generate future climate change scenarios. These were then used to drive distributed hydrologic models (Variable Infiltration Capacity, Soil and Water Assessment Tool) for hydrological simulation of the Yangtze River and Yellow River basins, thereby quantifying the effects of climate change on the basin water cycle. The results showed that suitability assessment adopted in this study could effectively reduce the uncertainty of GCMs, and that statistical downscaling was able to greatly improve precipitation and temperature outputs in global climate mode. Compared to a baseline period (1961–1990), projected future periods (2046–2065 and 2081–2100) had a slightly decreasing tendency of runoff in the lower reaches of the Yangtze River basin. In particular, a significant increase in runoff was observed during flood seasons in the southeast part. However, runoff of the upper Yellow River basin decreased continuously. The results provide a reference for studying climate change in major river basins of China.
REVIEW | doi:10.20944/preprints202202.0336.v1
Subject: Environmental And Earth Sciences, Water Science And Technology Keywords: Dam; River estuary; Ecosystem; Effect
Online: 25 February 2022 (13:16:40 CET)
Dams have made great contributions to human society, facilitating flood control, power generation, shipping, agriculture and industry. However, the construction of dams greatly impacts downstream ecological environments and nearby marine areas. To summarize these impacts, this review used recent research to comprehensively analyze how dam construction has affected river hydrology, geomorphology, and ecosystem of downstream reaches globally. Effects of dams on ecosystems occur through reduced river flow, reduced sediment flux, altered water temperature, changed estuary delta, altered composition and distribution of nutrients, altered structure and distribution of phytoplankton populations, caused habitat fragmentation, and blocked migration routes in river sections and adjacent seas. Besides, exploring new reservoir management strategies (including targeted control of dam storage and flushing sediment operations), banning fishing activities, and removing unnecessary dams (obsolete or small dams) are becoming crucial tools for ecosystem restoration.
ARTICLE | doi:10.20944/preprints202009.0617.v1
Subject: Environmental And Earth Sciences, Paleontology Keywords: elevation; habitat; hippo; Pleistocene; river
Online: 26 September 2020 (06:50:16 CEST)
In the late Pleistocene, a prehistoric hippo species was distributed from Africa to the Asia including Pakistan, India, and Java island. This study aims to model habitat suitability of Asian hippo known as a Hippopotamus sivalensis spp. in east Java. The measured parameters included the fossil locality, vegetation cover, elevation, and distance to the river in a forest river basin sizing 6652 Ha. Those parameters using GIS were weighted, overlaid, and interpolated to determine the most suitable habitats. The model projected that the suitable habitats of H. sivalensis spp. were in the central of the basin near the river. The largest suitable habitats were located in the eastern parts of basin which were dominated by forests
ARTICLE | doi:10.20944/preprints202308.1716.v1
Subject: Environmental And Earth Sciences, Geography Keywords: Universal Soil Loss Equation; erosivity; Pardo river basin (tributary of the São Francisco river)
Online: 24 August 2023 (08:18:56 CEST)
The study presented here, through the use of GIS and physical variables, generate a new meth-odology for the calculation of erosivity (Factor R) for the qualitative evaluation of soil loss po-tential (laminar erosion) in the Northwest margin of the municipality of São Francisco, mostly located in the Pardo-MG river basin. The results obtained were statistically correct when com-pared to the traditional R calculation and the laminar erosion methodology. It is worth noting that the new proposal presented here indicated sites of qualitative loss of soil in the same places where there are closed-loop satellite signals of degraded Cerrado, something not identified in the traditional model. As conclusion it can be said that the obtained results were extremely sat-isfactory, being advised more studies to verify this new method proposed here in more places beyond the study area elaborated here
ARTICLE | doi:10.20944/preprints202304.0629.v1
Subject: Environmental And Earth Sciences, Environmental Science Keywords: accretion; adaptive responses; Bangladesh; erosion; floods; geophysical; hazards; river basin; river channel migration; resettlement.
Online: 20 April 2023 (08:01:29 CEST)
This study posits that for appropriately explaining the complex charland (mid-channel island) processes and formulating policy and planning measures, a comprehensive understanding of the dynamic characteristics of the geomorphological, ecological, and human systems holistically is essential. This is also valid for the territorial and maritime areas of Bangladesh. The objectives of this study are: (i) to analyze the salient features and characteristics of the geomorphological and riparian systems of the Bengal Delta; (ii) to analyze the evolutionary discourse of the legal systems concerning eroded (diluvion) and accreted (alluvion) land in Bangladesh; and (iii) to assess characteristics of coping and adaptation strategies of the charland inhabitants. The findings reveal that the delta-building processes, characterized by the dynamic shifts of river channels, and erosion and accretion of charlands have made the land and water systems of the territory very dynamic and unstable – resulting in consistent displacement of settlers and serious deterioration of their socioeconomic status. The historical evolution of land laws and regulations concerning the accreted land favoured vested interests. As no effective institutional framework and structure presently exists in Bangladesh for resettlement planning, formulation of a comprehensive national resettlement policy is therefore urgently needed.
ARTICLE | doi:10.20944/preprints202303.0337.v1
Subject: Arts And Humanities, Classics Keywords: metabarcoding; statistical modeling; urban river ecology
Online: 20 March 2023 (03:30:47 CET)
In this study we sought to investigate the impact of urbanization, presence of concrete river bottom, and nutrient pollution on microbial communities along the L.A. River. Six molecular markers were evaluated for identification of bacteria, plants, fungi, fish, and invertebrates in 90 samples. PCA (principal components analysis) was used with PAM (partitioning around medoids) clustering to reveal community structure and an NB (Negative binomial) model in DESeq2 was used for differential abundance analysis. PCA and factor analysis exposed the main axes of variation but were sensitive to outliers. Differential abundance of Proteobacteria was associated with soft bottom sites, and there was an apparent balance in the abundance of organisms responsible for nitrogen cycling. Nitrogen cycling was explained by differential abundance of ammonia oxidizing archaea, the complete ammonia oxidizers Nitrospira sp., nitrate reducing bacteria Marmoricola sp., and nitrogen fixing bacteria Devosia sp. which were differentially abundant at soft-bottom sites (p adj < 0.002). In contrast, differential abundance of several Cyanobacteria and other anoxygenic phototrophs was associated with the concrete bottom sites, which suggested the accumulation of excess nitrogen. The soft bottom sites tended to be represented by differential abundance of aerobes, whereas the concrete-associated species tended to be alkaliphilic, saliniphilic, calciphilic, sulfate dependent, and anaerobic. In Glendale Narrows, downstream from multiple water reclamation plants, there were differential abundance of cyanobacteria and algae, however indicator species for low nutrient environments and ammonia-abundance were also present. There was differential abundance of ascomycetes associated with Arroyo Seco and a differential abundance of Scenedesmaceae green algae and cyanobacteria in Maywood, in the analysis which compared suburban with urban river communities. The proportion of Ascomycota to Basidiomycota within the LA River differed from the expected proportion based on published worldwide freshwater and river 18S data; the shift in community structure was most likely associated with the extremes of urbanization. This study indicates that extreme urbanization can result in overrepresentation of cyanobacterial species that could cause reductions in water quality and safety.
ARTICLE | doi:10.20944/preprints202301.0558.v2
Subject: Computer Science And Mathematics, Artificial Intelligence And Machine Learning Keywords: Heavy rainfall; River floods; Machine learning
Online: 20 February 2023 (14:23:25 CET)
Advancements in Machine Learning techniques, availability of more data-sets, and increased computing power have enabled a significant growth in a number research areas. Predicting, detecting and classifying complex events in earth systems which by nature are difficult to model is one of such areas. In this work, we investigate the application of different machine learning techniques for detecting and identifying extreme rainfall events in a sub-catchment within Pangani River Basin, found in Northern Tanzania. Identification and prediction of extreme rainfall event is a preliminary crucial task towards success in predicting rainfall-induced river floods. To identify a rain condition in the selected sub-catchment, we use data from five weather stations which have been labeled for the whole sub-catchment. In order to assess which Machine Learning technique suits better for rainfall identification, we apply five different algorithms in a historical dataset for the period of 1979 to 2014. We evaluate the performance of the models in terms of precision and recall, reporting Random Forest and XGBoost as the ones with best overall performance. However, since the class distribution is imbalanced, the generic Multi-layer Perceptron performs best when identifying the heavy rainfall events, which are eventually the main cause of rainfall-induced river floods in the Pangani River Basin
ARTICLE | doi:10.20944/preprints202301.0566.v1
Subject: Social Sciences, Sociology Keywords: Risk; resettlement; governmentality; development; river communities
Online: 31 January 2023 (02:36:54 CET)
Based on ten months of ethnographic fieldwork in marginal, low-income, Belenino river communities located in Iquitos, a fluvial city in the Amazon basin. By using ethnographic methods and semi-structured interviews, this article traces how risk is associated with life in Belenino communities and how the identity of Beleninos and the river at the heart of a resettlement project are politically constructed rather than empirically constructed. In this case study of resettlement, understandings of risk and development by Belenino river communities and the government both conflicted and overlapped, I identified three elements that help to shape the concept of risk in both groups that highlight the disjunctive meanings provided by culture and demonstrate the complexity of the analysis of both populations. Finally, by putting the state’s weak presence after a developmental project failure under ethnographic approximation, the article reveals an imbalance in validity and power in terms of the perspectives of the river and Belen.
ARTICLE | doi:10.20944/preprints202311.0969.v1
Subject: Environmental And Earth Sciences, Water Science And Technology Keywords: Magdalena River Estuary; Saline-Wedge Estuary; Saline-Wedge Interannual Variability; Discharge-salinity relationship; Magdalena River Mouth Siltation.
Online: 15 November 2023 (09:56:59 CET)
The linkage between the salt wedge, tidal patterns, and the Magdalena River discharge is established by assessing the ensuing parameters: stratification (ϵ), buoyancy frequency (β), potential energy anomaly (φ), Richardson number (RL), and bottom turbulent energy production (P). The salinity, temperature, density, and water velocity data utilized were derived from MOHID 3D, a previously tailored and validated model for the Magdalena River Estuary. To grasp the dynamics of the river, a flow regime analysis was conducted during both wet and dry climatic seasons of the Colombian Caribbean. The utilization of this model aimed to delineate the estuary's spatial reach, considering flow rates spanning from 2000 to 6500 m³/s across two tidal cycles. This approach facilitates the prediction of the position, stability, and stratification degree of the salt front. Among the conclusions drawn, it is highlighted that: 1. The river flow serves as the principal conditioning agent for the system, inducing a strong estuary response to weather stations; 2. The extent of wedge intrusion and the river discharge exhibit a non-linear, inversely correlation; 3. Tidal waves cause differences of up to 1000 m in the horizontal extent of the wedge; 4. Widespread channel erosion occurs during the rainy season when the salt intrusion does not exceed 2 km; 5. Flocculation processes intensify during the transition between dry and wet seasons; 6. The stability of the salt layering and the consolidation of the FSI-TMZ are contingent upon the geometric attributes of the channel.
ARTICLE | doi:10.20944/preprints202308.2194.v1
Subject: Environmental And Earth Sciences, Environmental Science Keywords: Hainan Island; Changhua River; Hydrogeochemistry; Controlling factors
Online: 31 August 2023 (15:05:14 CEST)
The lower reaches of the Changhua River are located in the northwest of Hainan Island, and the shallow groundwater in this area is the main water source for residents living at both sides of the river. In order to sustain the exploitation and use of water resources in this area, it is essential to clarify the chemical characteristics and the formation mechanism of the groundwater. We collected 100 sets of shallow groundwater samples from the lower reaches of the Changhua River, and analyzed the chemical characteristics of the groundwater in shallow aquifers as well as its controlling factors by means of the methods including descriptive statistical analysis, Piper diagram, Gibbs diagram, and ion ratio. The results show that the overall characteristics of groundwater in the study area are near-neutral to weakly alkaline nature, indicating a generally oxidized environment. The groundwater involves in 56 chemical types, and the most predominant types are Ca•Na-HCO3 and Ca-HCO3, respectively. NO- 3 has become a macro component exceeding SO2- 4in most of the sampling groundwater, suggesting a significant impact of human activities in this area. At the same time, the chemical characteristics of groundwater in the study area are mainly affected by the water-rock interaction, while the water-rock interaction is mostly affected by the dissolution of silicate rocks and less by the dissolution of carbonate rocks and evaporite rocks. According to the ion ratio results, Na+ and K+ in the study area are mainly from the leaching of silicate rocks, Ca2+ and Mg2+ are mainly from the dissolution of carbonate rocks, in addition to a certain degree of cationic exchange. NO- 3 is mainly related to human activities, and the human activities are more affected by agricultural activities and domestic sewage than by industrial and mining activities. This study can provide a reference for the development and protection of shallow groundwater in the lower reaches of the Changhua River.
REVIEW | doi:10.20944/preprints202305.0225.v1
Subject: Environmental And Earth Sciences, Environmental Science Keywords: radiation and chemical pollution; speciation; Yenisei River
Online: 4 May 2023 (08:09:11 CEST)
Man-made chemicals have played an important role in the development of our modern society. They have revolutionized such areas as healthcare and farming and they are essential in the manufacture of a wide range of consumer products. In studying the behavior of radionuclides and metals in the bottom sediment-water system, special attention is paid to identifying the forms of existence of pollutants in terms of substantiating their migration ability and, as a result, the po-tential for their subsequent spread, i.e. secondary pollution. On the example of bottom sediments of the Yenisei River, such radionuclides as K-40, Cs-137 are shown to be present mostly in the undecomposed residue. Eu-252 and Am-241 are associated with the organic component of bottom sediments, consisting of plant and animal remains, as well as soil washed away from the floodplain part of the river bed. The radionuclide Co-60, depending on the mineralogical composition of bottom sediments, can either be almost evenly distributed between the undecomposed residue and organic matter, or dominate in the undecomposed residue. Thus, it is shown that man-made ra-dionuclides can have a high tendency to migrate, both in the thickness of bottom sediments and between such phases as bottom sediments and water.
ARTICLE | doi:10.20944/preprints202109.0521.v2
Subject: Environmental And Earth Sciences, Geophysics And Geology Keywords: UAS; drone; Doppler radar; PIV; river; velocity
Online: 7 March 2022 (14:55:21 CET)
Surface velocity is traditionally measured with in situ techniques such as velocity probes (in shallow rivers) or Acoustic Doppler Current Profilers (in deeper water). In the last years, researchers have developed remote sensing techniques, both optical (e.g., image-based velocimetry techniques) and microwave (e.g., Doppler radar). These techniques can be deployed from Unmanned Aerial Systems (UAS), which ensure fast and low-cost surveys also in remotely-accessible locations. We compare the results obtained with a UAS-borne Doppler radar and UAS-borne Particle Image Velocimetry (PIV) in different rivers, which presented different hydraulic–morphological conditions (width, slope, surface roughness and sediment material). The Doppler radar was a commercial 24 GHz instrument, developed for static deployment, adapted for UAS integration. PIV was applied with natural seeding (e.g., foam, debris) when possible, or with artificial seeding (woodchips) in the stream where the density of natural particles was insufficient. PIV reconstructed the velocity profile with high accuracy typically in the order of a few cm s−1 and a coefficient of determination (R2) typically larger than 0.7 (in half of the cases larger than 0.85), when compared with acoustic Doppler current profiler (ADCP) or velocity probe, in all investigated rivers. However, UAS-borne Doppler radar measurements show low reliability because of UAS vibrations, large instrument sampling footprint, large required sampling time and difficult-to-interpret quality indicators suggesting that additional research is needed to measure surface velocity from UAS-borne Doppler radar.
HYPOTHESIS | doi:10.20944/preprints202203.0027.v1
Subject: Biology And Life Sciences, Animal Science, Veterinary Science And Zoology Keywords: camouflage; colouration; arsenic; toxicity; common river prawn
Online: 1 March 2022 (16:29:06 CET)
Camouflage is an interesting adaptation (for survivability) by organisms in terms of different aggregation or fusion of colourations. Understanding these camouflage strategies in the presence of arsenic on transparent/semi-transparent species is pretty challenging. Previously, several researchers have demonstrated that colouration or pigmentation strategy in an organism is a strategy to merge with the environment to escape from predatory threats. Our study was done on a semi-transparent freshwater prawn species which exhibits a strategy of pigment droplets on its exoskeleton. Unlike previous studies, our findings robustly indicate the fact that pigment droplets are not the only reason for colouration. The pigment droplets rather regulate the darkness of the exoskeleton. However, the transparency of the abdominal muscles additionally plays a crucial role in creating a background of the pigment droplets. The transparency muscles allow light to pass through the abdomen, thus creating a semi-transparent appearance. The degree of semi-transparency is also regulated by the intensity of light. The abdomen and the pigment droplets on the exoskeleton cumulatively as well as contrastingly maintain the transparency and the colour quotient of the prawns. In our study, we have majorly concentrated on the abdominal region of the prawns as it appears to be the key semi-transparent feature of the organism. This research is directed to an ecotoxicological aspect where we showed that arsenic in chronic non-lethal concentration, can notably alter the colouration pattern in this prawn model within a short period of time. Finally, we have used an image processing algorithm to assess the alteration of colouration in this organism.
ARTICLE | doi:10.20944/preprints202009.0260.v1
Subject: Environmental And Earth Sciences, Geography Keywords: LiDAR; Bergama; Alluvial Fan; Geomorphology; Bakırçay River
Online: 13 September 2020 (11:25:59 CEST)
Topography represented by high resolution digital elevation models are able to inform past and present morphological process on the terrain. High resolution LiDAR data taken by the General Directorate of Map at the surroundings of the Bergama city shows great opportunities to understand the morphological process on alluvial fan on which the city is located and the flood plain of Bakırçay river near the alluvial fan. In this paper the LiDAR data collected in 2015 have been used to create DEM’s to understand the geomorphological evolution of the alluvial fan and the flood plain around it. Since the proximal roots and medial parts of the alluvial fan have been the scene for a long human settlement most topographical traces of the morphological process have been distorted. Nevertheless, the traces of past and present morphological process at the distal fan which consist the contact zone with the flood plain are very clear on the DEM created from LiDAR data. The levees and some old courses of Bergama and Bakırçay rivers have been shown on the maps which are also important to understand the ancient roads which follows these levees.
ARTICLE | doi:10.20944/preprints201912.0155.v1
Subject: Environmental And Earth Sciences, Environmental Science Keywords: pollution sources; sediments; Palizada river; heavy metals
Online: 12 December 2019 (01:54:59 CET)
The fluvial-lagoon-deltaic system of the Palizada river in Campeche is an ecosystem of socioeconomic and ecological importance. It is justifiable to carry out studies in this system, due to its connection with another larger ecosystem called Términos lagoon. The objective of this investigation was to analyze the concentration of Pb and Cd in sediments of the fluvial-lagoon-deltaic system of the Palizada river and to determine, with this, the contamination index of these metals. Cd presented the highest concentration in sampling sites and climatic seasons with respect to Pb, with a maximum value of 53.926 ± 5.045, while Pb was 10.421 ± 0.218 μg g-1. The same tendency was presented with pollution and geoaccumulation indexes, where the Cd index stands out. The enrichment of heavy metals was identified through the accumulation of Cd and Pb, such process was evaluated through the geoacumulation index (Igeo). The results of this indicated that these elements are contaminating with an anthropogenic origin mainly. This element represents a toxic risk for the Palizada system, due to its high toxicity even at low concentrations, as well as to evaluate the sublethal effects in organisms that inhabit this system and it requires the implementation of an integral monitoring.
ARTICLE | doi:10.20944/preprints202307.1549.v1
Subject: Environmental And Earth Sciences, Water Science And Technology Keywords: climate change; water potential; RCM; Arba River; Ethiopia
Online: 24 July 2023 (10:57:56 CEST)
This study was investigate the possible hydrological impact of climate change in stream flow of Arba River based on the downscaled precipitation and temperature data at West Harerghe Zone, Oromia regional state, Ethiopia. The case study, Arba River is one of the tributaries of Awash River Basin and the catchment of the river at Bordode flow gauging station covers around 72 square kilometers. Dynamically downscaled Regional Climate Model (RCM) HIRHAM derived by ICHEC-EC-EARTH global climate model under two scenarios RCP 4.5 and 8.5 was used in this study. The future time periods are divided into two time horizons with equal length of time as the base line period 2021–2050 and 2051–2080. For both projected periods relatively the minimum average monthly percentage change in precipitation will be happened from May to October under RCP4.5 except August and from March to October under RCP8.5. The variation under RCP4.5 is relatively high when compared to RCP8.5. The average monthly per-centage of flow increment may vary from (7.6 to 81.8) for 2021-2050 and (22.3 to 107.8) for 2051-2080 under RCP4.5. Under RCP8.5 scenario, from July to January except the December for 2021-2050, simulated flow is expected to increase while from February to June decreases for both time horizons. Generally, the change of simulated flow under both scenarios and both near and far time period is follows the pattern of precipitation. However, the flow change will have less variation than the precipitation change.
ARTICLE | doi:10.20944/preprints202302.0432.v1
Subject: Engineering, Civil Engineering Keywords: Climate Change; Consumptive Demands; São Francisco River reservoirs.
Online: 27 February 2023 (02:35:08 CET)
Climate change in the coming decades could intensify extreme events such as severe droughts. Combined with the possible increase of water demands, these changes exert a large pressure on the water systems. In order to confirm this assumption, a set of scenarios was proposed in this study to consider the combined impact of climate changes and the increase in water demand on the main multiple-use reservoirs of São Francisco River, Brazil. For this purpose, five CMIP6 climate models were used considering two greenhouse gas emissions scenarios: the SSP2-4.5 and SSP5-8.5. The naturalized and withdraw streamflows were estimated to the adopted reser-voirs considering all existing, new and projected demands. The conjunction of scenarios indicat-ed an increase in Potential Evapotranspiration, a possible significant reduction in water availa-bility, a growth in water demand mainly for irrigation and a substantial reduction in the perfor-mance of the evaluated reservoirs.
ARTICLE | doi:10.20944/preprints202206.0422.v1
Subject: Environmental And Earth Sciences, Environmental Science Keywords: metals; trace elements; landscape; permafrost; river; watershed; boreal
Online: 30 June 2022 (08:44:41 CEST)
Towards a better understanding of vegetation, permafrost, climate, landscape and lithology control on major and trace element (including macro and micro-nutrients and toxicants) transport in riverine systems, we studied two medium size (100-150 thousand km² watershed area) pristine rivers (Taz and Ket) of boreal and subarctic zone, western Siberia. Choosing the river basins of very low population density (< 1 people km-²) in the absence of any industrial or agricultural activity allowed testing the sole effect of natural factors and long-range atmospheric transfer on hydrochemistry of riverine solutes during the open water period. In the permafrost-bearing Taz River (main stem and 17 tributaries), sizable control of vegetation on element concentration was revealed. In particular, light coniferous and broadleaf mixed forest controlled DOC, and some nutrients (N, Mn, Fe, Mo, Cd, Ba); deciduous needleleaf forest positively correlated with macronutrients (P, Si, Mg, P, Ca) and Sr, and dark needle-leaf forest impacted Ntot, Al and Rb. Organic C stock in the upper 30-100 cm soil positively correlated with Be, Mn, Co, Mo, Cd, Sb, and Bi. The lithological control was generally poorly pronounced, due to abundant peat deposits overlaying the mineral strata. However, cretaceous carbonate mineral-bearing sedimentary deposits positively impacted the pH and concentration of Si, Mg, Ca and Cs. In the Ket River basin (large right tributary of the Ob River), we revealed the correlations between the phytomass stock at the watershed and alkaline-earth metals and U concentration in the river water. This control was weakly pronounced during high-water period (spring flood) and mostly evidenced during summer low water period.
ARTICLE | doi:10.20944/preprints202203.0017.v1
Subject: Environmental And Earth Sciences, Geophysics And Geology Keywords: East Asia; Detrital zircon; Large River; Rift Basin
Online: 1 March 2022 (11:07:26 CET)
The forming of large rivers are the integral consequences of the deep earth process and the surface. In contrast to the hot topics for rivers related to orogenic domains, rift-related large rivers are largely ignored especially in deep time studies. The Cenozoic East Asia margin provides very good opportunity to observe this kind of rivers. It has been believed that basin-and-swell physiography dominated the East Asia margin and impeded the forming of large rives in the early Cenozoic. In this paper, we combined provenance analysis of East China Sea Basin, where is a crucial place to trace the river evolution in East Asia margin, and regional geologic constraints to reveal drainage reorganizations. Detrital zircon U-Pb ages from the Early Eocene sediments of the East China Sea Basin are firstly reported. Our results together with literature data demonstrate that regional provenance changes occurred at the middle Eocene from one singe age peak at ~110 Ma of proximal sources to multiple age spectrum derived from far inland. Source to sink analysis indicated that the North China Block and Korea Peninsular provided the most detritus. Sedimentation and tectonic features of rift basins in the potential source areas indicated that rivers flowed into Bohai Basin and Jianghan Basin cannot provide terrigenous clasts for the lower reaches in the Eocene. Contrastingly, the dominantly fluvial sediments across the Subei-South Yellow Sea Basin suggested external river system and a bypassing region since the middle Eocene, coinciding with provenance change in ECSB. All these demonstrated that a large river (East Asia River) established in east Asia margin in the middle Eocene and flowed southwestward approximately 1500km to the sea in southern ECSB. This river might last to the middle Miocene. The deep earth processes driven by Izanagi-Pacific ridge subduction resulted in the overfilled stage of Subei-South Yellow Sea Basin and the post-rift subsidence in west depression of ECSB, and thus facilitated the initiation of the EAR. Our finding shed new light on the evolving landscape in East Asia and showed how subduction of deep earth process controlled the initiation of rift-related large rivers.
ARTICLE | doi:10.20944/preprints202110.0328.v1
Subject: Biology And Life Sciences, Ecology, Evolution, Behavior And Systematics Keywords: finfish; shellfish; biodiversity indices, ecological pollution; Payra river
Online: 22 October 2021 (11:58:21 CEST)
The Payra River is one of the large coastal rivers in Bangladesh which supports incredible fish species and has been affected by extensive human disturbance due to huge fishing pressure. The present study provides information about the temporal diversity of finfish and shellfish concerning climatological variables and ecological pollution along with threat assessment in the Payra River, Patuakhali. During the entire study, a total of 61 fish species including 56 finfish and 5 shellfish species were recorded under 22 families belonging to 11 orders. The order-wise fish species availability showed that the Perciformes (29.49%) was the dominant order based on species richness. Among them, 4 endangered, 6 vulnerable, 4 near threatened, 42 least concern, and 5 data deficient species were found. During the study period, the average Shannon-Weaver diversity index value was (3.33±0.12) indicates a good spread of fish population in the Payra river. Average Margalef richness index value was found (7.60±0.32), Pielou's evenness index (0.48±0.05), and Simpson dominance index (0.93±0.02) in Payra river. Dominance and Richness index value indicates clear water environment to slight pollution in the Payra river. Ten different kinds of fishing gears were identified under 3 major groups including 5 nets, 3 hooks and lines, and 2 traps. The phytoplanktonic genus and species revealed moderate pollution. Canonical correspondence analysis ordination plot showed that rainfall was the most influencing driving force among the meteorological parameters. The cluster analysis based on the Bray-Curtis similarity matrix showed that the winter season formed a separate cluster. In the recapitulation, the Payra River is a highly productive system that provides a favorable environment for a large variety of finfish and shellfish species assemblages. Findings of the conducted study are expected to be helpful for the respective researchers, policymakers, managers, and conservationists for the sustainable management of this water body and the interconnected surrounding neighboring countries.
ARTICLE | doi:10.20944/preprints202109.0314.v1
Subject: Medicine And Pharmacology, Pathology And Pathobiology Keywords: GeneXpert; MDR-TB; Prevalence; River Nile State; Sudan
Online: 17 September 2021 (12:41:23 CEST)
Background: World Health Organization (WHO) estimates that there were 558000 new cases with resistance to Rifampicin, of which 82% had multidrug-resistant tuberculosis (MDR-TB). Objectives: We aimed to identify the prevalence of MDR-TB in River Nile state, Sudan, and the risk factors contributing to its occurrence. Methods: This was a descriptive cross-sectional hospital-based study involved 200 specimens taken from patients suspected of having MDR-TB tested using an automated GeneXpert assay. Results: Results of GeneXpert assay showed that the presence of Mycobacterium tuberculosis in 81 (40.5%), and out of 81 positive test results there were 13 (16%) had MDR-TB. Additionally, 7 cases of MDR-TB were previously treated which represented about (53%) of MDR patients, the remaining 6 MDR-TB patients were new cases and represented (47%) of MDR-TB patients. Moreover, there were 4 MDR-TB patients who had a history of contact with MDR-TB patients. Conclusion: Prevalence of MDR-TB in River Nile State, Sudan was 16%, which is greater than WHO estimation for Sudan (10.1%). The results revealed that the main risk factor to develop MDR-TB was a history of contact with MDR-TB, so adherence to treatment and social awareness about the spread of MDR-TB are crucial preventive measures.
ARTICLE | doi:10.20944/preprints202105.0375.v1
Subject: Environmental And Earth Sciences, Atmospheric Science And Meteorology Keywords: Metals; Environmental monitoring; Bioassays; Amazon River; Amazon; mining
Online: 17 May 2021 (09:42:51 CEST)
As the number of legal and illegal mining sites increase, integrative methods to evaluate the effects of mining pollution on Andes-Amazonia freshwater ecosystems are paramount. Here, we sampled water and sediments in 11 sites potentially affected by mining activities in the Napo province (Ecuador). The environmental impacts were evaluated using four lines of evidence (LOEs): water physico-chemical parameters; metal exposure concentrations; macroinvertebrate community response (AAMBI); and toxicity by conducting bioassays with Lactuca sativa and Daphnia magna. Overall, dissolved oxygen and total suspended solids were, under (<80%) and above (>130 mg/Ls) quality standards. Ag, Al, As, Cd, Cu, Fe, Mn, Pb and Zn in water and V, B and Cr in sediments were detected above quality standards. Nine out of eleven sites were classified as having bad environmental quality based on the AAMBI. Ranges of L. sativa seed germination in both water (37% to 70%) and sediment (0% to 65%), indicate significant toxicity. In 5 sites, neonates of D. magna showed a 25% reduction in survival compared to the control. Our integrated LOEs index ranked sites regarding their environmental degradation. Given the importance of the Andes-Amazon region, we recommend environmental impact monitoring of the mining expansion using multiple LOEs.
ARTICLE | doi:10.20944/preprints202102.0273.v1
Subject: Business, Economics And Management, Accounting And Taxation Keywords: Landscape Ecology; Lake; River; Urban Ecosystem; Urban Forest
Online: 11 February 2021 (09:46:04 CET)
Within the town, Abiotic is a built environment that includes buildings, roads, pedestrians, and other elements that interact with biotics, which are living things including plants, animals, and humans. From a landscape ecological perspective, the urban structure consists of (1) a matrix, which is a collection of dominant buildings and homogeneous elements, (2) Patches are grouped as housing, urban forests, parks, lakes, and finally (3) Corridors such as roads, rivers, and pedestrians. The dominance of watertight areas over green open spaces in urban development can lead to increased temperatures and runoff. The condition of the soil structure and the steep slope of the soil can cause landslides, therefore urban development must pay attention to the natural conditions of the area being built. This research was conducted in Kota Baru, Bogor, South Tangerang, and Cikarang (Bekasi Regency). The purpose of this study is to determine the natural environment and the built environment as well as changes in the ecosystem and their consequences for the new town and its surroundings. This research uses quantitative and qualitative approaches. Analysis of land-use change uses spatial and temporal methods, while Nieuwolt's equation is used to measure comfort. This study finds comfortable environmental planning, with green open spaces such as urban forests, city parks, and bodies of water, such as lakes, as a space for interaction between fellow new city residents and people outside the new towns.
ARTICLE | doi:10.20944/preprints202012.0531.v1
Subject: Environmental And Earth Sciences, Atmospheric Science And Meteorology Keywords: River mouth; Rupat Strait; sediment transport; tidal current
Online: 21 December 2020 (14:32:15 CET)
The Rupat Strait, a part of the Malacca Strait, is recognized as semi-closed waters and shows a high activity; thus, discovering the transport sediment mechanism of the strait as a consequence of ambient and anthropogenic forces is essential. Hydrodynamic and sediment transport modelling was constructed using the 2-Dimensional Explicit method which is averaged over depth. The results show that the dispersion of sediment at high tide is longer than that at low tide. This follows the hydrodynamic model in which current velocity at high tide is greater than the ocean current at the low tide. The previous sediment observation supports the results of transport sediment modelling, indicating that the anthropogenic factors are highly associated with the sedimentation in the Rupat strait
ARTICLE | doi:10.3390/sci1020049
Subject: Environmental And Earth Sciences, Atmospheric Science And Meteorology Keywords: climate change; temperature trend; Himalaya; river basin; Nepal
Online: 14 August 2019 (00:00:00 CEST)
Study of spatiotemporal dynamics of temperature is vital to assess changes in climate, especially in the Himalayan region where livelihoods of billions of people living downstream depends on water coming from the melting of snow and glacier ice. To this end, temperature trend analysis is carried out in Narayani river basin, a major river basin of Nepal characterized by three climatic regions: tropical, subtropical and alpine. Temperature data from six stations located within the basin were analyzed. The elevation of these stations ranges from 460 to 3800 m a.s.l. and the time period of available temperature data ranges from 1960–2015. Multiple regression and empirical mode decomposition (EMD) methods were applied to fill in missing data and to detect trends. Annual as well as seasonal trends were analyzed and a Mann-Kendall test was employed to test the statistical significance of detected trends. Results indicate significant cooling trends before 1970s, and warming trends after 1970s in the majority of the stations. The warming trends range from 0.028
" style="position: relative;">∘C year ∘ " style="position: relative;">−1 to 0.035 − 1 " style="position: relative;">∘C year ∘ " style="position: relative;">−1 with a mean increasing trend of 0.03 − 1 " style="position: relative;">∘C year ∘ " style="position: relative;">−1 after 1971. Seasonal trends show highest warming trends in the monsoon season followed by winter, pre-monsoon, and the post-monsoon season. However, difference in warming rates between different seasons was not significant. An average temperature lapse rate of −0.006 − 1 " style="position: relative;">∘C m ∘ " style="position: relative;">−1 with the steepest value (−0.0064 − 1 " style="position: relative;">∘C m ∘ " style="position: relative;">−1) in pre-monsoon season and least negative (−0.0052 − 1 " style="position: relative;">∘C m ∘ " style="position: relative;">−1) in winter season was observed for this basin. A comparative analysis of the gap-filled data with freely available global climate datasets show reasonable correlation thus confirming the suitability of the gap filling methods.
REVIEW | doi:10.20944/preprints201906.0161.v1
Subject: Environmental And Earth Sciences, Geophysics And Geology Keywords: Numerical modelling; landscape evolution; surface processes; river networks
Online: 17 June 2019 (10:37:13 CEST)
Currently, the use of numerical models for reproducing the landscape evolution of a river basin is part of the day-by-day research activities of fluvial engineers and geomorphologists. However, despite landscape modelling is based on a rather long tradition, and scientists and practitioners are trying to schematize the processes involved in the evolution of a landscape since decades, there is still the need for improving both the knowledge of the physical mechanisms and their numerical coding. The present review focuses on the first aspect, discussing the main components of a landscape evolution model and their more common schematizations, presenting possible open questions to be addressed towards an improvement of the reliability of such kind of models in describing the fluvial geomorphology.
ARTICLE | doi:10.20944/preprints201805.0107.v1
Subject: Engineering, Civil Engineering Keywords: river-connected lake; Cu, Jinshan lake; tidal action
Online: 7 May 2018 (08:22:55 CEST)
A typical river-connected lake, Jinshan Lake, was selected as the study area. By the combination of field experiment, laboratory experiment and mathematical model, we plotted the relationship between the concentration of DCu-SCu and FDI, and constructed the mathematical model of the migration and transformation of HMCu in Jinshan Lake. We choose a typical diurnal tide to simulate and revealed the vertical migration characteristics of HMCu in Jinshan Lake during a diurnal tide. The results show that: (1) The release rate of DCu was proportional to FDI and background content, respectively. (2) Due to the nearby industrial enterprises and terrain characteristics, SA loads the most HMCu, the average concentration is 70.07mg/kg. According to the characteristics and geographical location of LC, the concentration of copper in the two states fluctuates greatly (DCu: 43.20~74.77 mg/kg, SCu: 53.63~74.67mg/kg). The fluctuation trend of SCu in ZA is significantly different from that in other areas, which mainly due to the complex hydraulic distribution and the sorption-desorption process of HMs in sediment particles. The hydraulic disturbance of JG is the least and relatively stable, which is the farthest from the inlet of the lake and is the least affected by the Yangtze river. (3) The FDI in a diurnal tide reaches the suspension condition of fine sediment particles in each region. FDI and sediment concentration on the vertical exchange of two - state Cu is significant.
ARTICLE | doi:10.20944/preprints201803.0199.v1
Subject: Engineering, Civil Engineering Keywords: Reservoir operation; SWAT; Genetic Algorithm; Urbanisation; Ganga River
Online: 23 March 2018 (15:07:22 CET)
Reservoirs are recognized as one of the most efficient infrastructure components in integrated water resources management and development. At present, with the ongoing advancement of social economy and requirement of water, the water resources shortage problem has worsened, and the operation of reservoirs, in terms of consumption of flood water, has become significantly important. Reservoirs perform both regulation of flood and integrated water resources management, in which the flood limited water level is considered as the most important parameter for trade-off between regulation of flood and conservation. To achieve optimal operating policies for reservoirs, large numbers of simulation and optimization models have been developed in the course of recent decades, which vary notably in their applications and working. Since each model has their own limitations, the determination of fitting model for derivation of reservoir operating policies is challenging and most often there is always a scope for further improvement as the selection of model depends on availability of data. Subsequently, assessment and evaluation associated with the operation of reservoir stays conventional. In the present study, the Soil and Water Assessment Tool (SWAT) models and a Genetic Algorithm model has been developed and applied to two reservoirs in Ganga River basin, India to derive the optimal operational policies. The objective function is set to minimize the annual sum of squared deviation form desired irrigation release and desired storage volume. The decision variables are release for irrigation and other demands (industrial and municipal demands), from the reservoir. As a result, a simulation-based optimization model was recommended for optimal reservoir operation, such as allocation of water, flood regulation, hydropower generation, irrigation demands and navigation and e-flows using a definite combination of decision variables. Since the rule curves are derived through random search it is found that the releases are same as that of demand requirements. Hence based on simulated result, in the present case study it is concluded that GA-derived policies are promising and competitive and can be effectively used operation of the reservoir.
ARTICLE | doi:10.20944/preprints202002.0387.v1
Subject: Engineering, Energy And Fuel Technology Keywords: hydrothermal energy; river-water heat pump; water temperature recovery distance; heat transfer equation; Environmental Fluid Dynamic Code (EFDC); Han river basin
Online: 26 February 2020 (02:58:42 CET)
Temperature differences between the atmosphere and river water allow rivers to be used as a hydrothermal energy source. The river-water heat pump system is a relatively non-invasive renewable energy source; however, effluent discharged from the heat pump can cause downstream temperature changes which may impact sensitive fluvial ecosystems. In this study, the water temperature recovery distance of the effluent was estimated for a river section in the Han River Basin, Korea, using the heat transfer equation and the Environmental Fluid Dynamic Code (EFDC) model. Results showed that, compared to the EFDC model, the heat transfer equation tended to overestimate the water temperature recovery distance due to its simplified assumptions. The water temperature recovery distance could also be used as an objective indicator to decide the reuse of downstream river water. Furthermore, as the river system was found to support an endangered fish species that is sensitive to water environment changes, care should be taken to exclude the habitats of protected species affected by water temperatures within water temperature recovery distance.
REVIEW | doi:10.20944/preprints202310.1979.v1
Subject: Engineering, Civil Engineering Keywords: plastic pollution; microplastic; nano plastic; marine pollution; river pollution
Online: 31 October 2023 (09:35:44 CET)
Plastic poses a significant threat to the environment, polluting land, water, and air. It is a broad term encompassing a variety of polymers. In the form of microplastics and nanoplastics, it can induce toxicity in water bodies. Plastic debris not only physically pollutes freshwater, but also chemically, undergoing changes over time due to hydroclimatic effects. Rivers serve as conduits, transporting plastics from minor tributaries to major rivers and ultimately into the ocean, endangering marine life. India, as a developing country with the largest population and numerous rivers, generates a significant amount of plastic waste, a substantial portion of which finds its way into rivers, leading to alarming rates of plastic accumulation in the ocean. Previously, policymakers focused primarily on landfills for plastic waste, neglecting the pollution of water bodies. The consequences of this neglect are evident, with major rivers in the country severely affected by plastic waste, necessitating advanced, efficient, and sustainable solutions. This study aims to establish a comprehensive framework for managing plastic waste, understanding its transport mechanisms to the ocean, and recognizing the threats it poses to life. It also expounds on harmful plastic pollutants in water, globally adopted technologies, and emphasizes the need for further research and data collection in this field. The primary concluding point is to prevent plastics from entering waterways and to actively collect river and marine plastic pollution. Banning single-use plastics and implementing efficient collection methods are crucial in containing plastic pollution. Effluents from industries should not be overlooked, as they often contain harmful micro and nanoplastics with ecotoxicological effects. The innovative concept of the "4Rs" - Refuse, Reduce, Reuse, and Recycle - stands as the cornerstone for safeguarding the environment against plastic pollution.
ARTICLE | doi:10.20944/preprints202310.0535.v1
Subject: Chemistry And Materials Science, Applied Chemistry Keywords: Dissolved Calcium; Kentucky Lake; Streams; Ohio River; Zebra Mussel
Online: 9 October 2023 (12:33:42 CEST)
Dissolved calcium (Ca2+) concentrations in freshwater ecosystems are of growing concern as increasing levels have been implicated in altering the environmental conditions and biodiversity. Elevated Ca2+ levels and sporadic re-emergence and disappearance of invasive zebra mussels in Kentucky Lake in recent years served as a motivation for this study. The objective of this study was to determine Ca2+ spatial and temporal patterns in Kentucky Lake, selected tributary streams, and the Ohio River during and following a zebra mussel invasion. Over 1000 water samples were collected and analysed for dissolved calcium during 2018-2022. Approved analytical methods were followed for sampling and measuring dissolved calcium levels. Results revealed significant spatial and temporal patterns. Kentucky Lake Ca2+ levels varied between 15-25 mg/L depending on the sampling location and month/year. Kentucky Lake channel sites exhibited comparably higher concentrations of Ca 2+ than did most embayment and/or stream sites, indicating that tributary streams did not serve as primary sources of calcium to the lake. Dissolved calcium levels at main lake sites exceeded the threshold for zebra mussel growth and reproduction in 2018 during the time when zebra mussels were present. Calcium in lake water samples collected from 2019 through 2022 was at or just below the threshold. Temporal trend data showed a gradual increase in Ca2+ in Kentucky Lake throughout the study period but remaining at or below the threshold level considered critical for the zebra mussels’ reproduction and development. Calcium levels in the Ohio River site at Paducah were similar to Kentucky Lake reflecting the predominance of Tennessee River water, while levels at the Brookport site were consistent with values known to support zebra mussel populations. The elevated calcium levels in Kentucky Lake waters during the late winter and early spring months may be due to natural sources (mineral weathering) as well as human activities in the Tennessee River basin. This study emphasizes the need for continued calcium monitoring in the watershed to determine the potential for future zebra mussel outbreaks and potential influences on the lake ecosystem and its functions.
ARTICLE | doi:10.20944/preprints202308.0896.v1
Subject: Environmental And Earth Sciences, Water Science And Technology Keywords: river monitoring; image-based; discharge estimation; open-source software
Online: 11 August 2023 (07:54:42 CEST)
River monitoring has the potential to grow substantially with present-day available affordable and locally sourced hardware. Yet river monitoring networks are still under pressure due to lack of resources, difficulties with maintenance, and rapidly changing conditions which in part may be due to climate change. We advocate that to turn around this trend, monitoring stations must rely on local people, work with locally available devices, work without contact with water and operate through openly available knowledge. River observations with camera videos have this potential. IP cameras, drones or smartphones are widely available as observation platforms. The scientific methods are well established in literature. Yet current attempts to establish scalable open-source software solutions that can be operated anywhere are lacking. In fact, currently available software is either research-oriented, more aimed at incidental observations, is restricted to single-use licenses, entirely proprietary, or restricted to operations through a third-party Software as a Service. To overcome this obstacle, we present OpenRiverCam, a free and open-source software ecosystem for river observations that can fulfill a wide variety of use cases and business cases through a well-documented and simple to use Application Programming Interface, service workflows, cloud scalability and interoperability, and options to extend to several applications within the hydrological, hydrodynamic, environmental and geospatial domains. We demonstrate its current technical abilities through three different case studies that all originate from a user perspective. We discuss the future developments to meet further requirements, which include documentation, widely available training materials and embedding in curricula, and further hardware and software developments.
ARTICLE | doi:10.20944/preprints202308.0763.v1
Subject: Environmental And Earth Sciences, Environmental Science Keywords: social inequalities; water dynamics; São Francisco River; Climate change.
Online: 9 August 2023 (14:36:18 CEST)
Water scarcity is a worldwide concern, considering that water is a limited resource and essential for life. In Brazil, approximately 30% of its population lives in one of the areas that most suffer from lack of water, the semi-arid region covering about 20% of the country's territorial extension. The lack of water, mainly in the northeast of the country, has been a problem for years, where people who live in this territory have been suffering for months from the lack of water and the poor distribution of the resource, which increases the degree of inequality between the regions of the country. The research aims to show the effect of the hydrological cycle on the quality of vegetation and how such processing can end up affecting people's lives and the environment. The municipality of Floresta is within the scope of sub-basin 73, the territory is part of the municipalities benefited from the PISF- São Francisco River integration project works, and the study has raised discussion on the part of the scientific community regarding the effectiveness of the population project and the possible risks caused to the environment. This study carried out a temporal analysis, 1961-2021, to investigate water availability and how the hydrological system can affect society, raising the degree of its importance for a better quality of life and consequently reducing hydric inequalities. It was also evaluated how climate changes can interfere with these environmental changes and the quality of life at the local scale. The hydrological model system used to assess water availability was the Pernambuco Hydrological Response Units SUPer-System. In addition, this system helped to understand the changes that occurred in the studied sub-basin. Yet was used UAV-Unmanned Aerial Vehicles to view relationship between lives in house and environment conditions. The study can obtain accurate and necessary information to understand the dynamics of the hydrological system and the possible changes of social hydric inequalities. Thus, it is concluded that climate change will have different impacts on small scales and lives conditions due to different characteristic's environment. It is very important to carry out studies on a detailed scale to provide better public policies for mitigating the effects of climate change on people's lives.
HYPOTHESIS | doi:10.20944/preprints202308.0371.v1
Subject: Environmental And Earth Sciences, Environmental Science Keywords: kaingen river; mangrove; carbon stored; carbon sequestration; allometric equation
Online: 4 August 2023 (08:42:11 CEST)
Mangroves play an important role as a carbon sink and in mitigation of climate change. This study aimed to assess the anthropogenic activities, water and soil quality, mangrove diversity, and carbon sequestration potential of mangrove trees in the Kaingen River, Kawit, Cavite. The sampling period was conducted from November 2022 to March 2023 with the established three sampling sites. The DENR Administrative Order (DAO)- 2016-08 was used as a standard for water quality parameters, except for phosphates which used DAO-2021-19. The soil parameters were identified using the soil test kit from the Bureau of Soil and Water Management (BSWM) and at the BSWM laboratory. Mangrove species were identified using The Field Guide for Philippine Mangroves and were verified by experts. The carbon sequestration potential was obtained using an allometric equation for Southeast Asian mangroves. There are three mangrove species found in Kaingen Riverine such as Rhizophora mucronata, Avicennia alba, and Xylocarpus granatum. Based on species importance value Rhizophora mucronata is the dominant mangrove species. The result for carbon sequestration of each mangrove species showed that Rhizophora mucronata yielded the highest carbon stored (35.16 tC/ha) and carbon sequestered (128.92 tCO2/ha). Among all the sampling sites, site 3 yielded the highest carbon stored (30.76 tC/ha) and carbon sequestered (112.81 tCO2/ha) in Kaingen River. Overall, the results of the study showed that Kaingen River can potentially store carbon at 71.89 tC/ha and CO2 sequestered at 263.62 tCO2/ha. This urges to practice conservation and protection measures for the mangroves forest of Kaingen River.
ARTICLE | doi:10.20944/preprints202306.1303.v1
Subject: Environmental And Earth Sciences, Sustainable Science And Technology Keywords: rural settlement; spatial distribution; Shiyang River Basin; arid area
Online: 19 June 2023 (05:38:57 CEST)
In the context of the rural revitalization strategy, it is urgent to accurately grasp the spatial differentiation characteristics and influencing factors of rural settlements in underdeveloped arid inland river basins. Taking the Shiyang River Basin as an example, the rural settlements from 2000 to 2019 were obtained by visual interpretation using satellite remote sensing data and official statistical data. Following the logical of "state characteristics - evolutionary patterns - influence factors - layout optimization", the average nearest index, gravity-center migration model, spatial statistical analysis and other methods were used combine with GIS. The spatiotemporal pattern evolution characteristics of rural settlements in the past 20 years have been analyzed. The results revealed the following: 1) The distribution pattern of rural settlements in the study area is sheet-like and strip-shaped. The projects in the southeast are mostly distributed in a patchy pattern with high density, while the characteristics in the west and north are exactly opposite. The objects in the south are distributed in the alluvial area of rivers, while settlements in the north are located in the oasis area. 2) From 2000 to 2019, the scale of rural settlements in the Shiyang River Basin, where simultaneous occurrence of new-built and disappearing phenomena, shows an expansion trend that fast firstly and then slow. Spatially, rural settlements in the basin show a trend of clustering towards the southwest. 3) The distribution characteristics of rural settlements are close to water and roads, greatly influenced by urban-rural integration and ecological migration. The results will provide scientific basis for accelerating the modernization of rural areas, and the construction of new rural areas according to local conditions.
ARTICLE | doi:10.20944/preprints202305.0238.v1
Subject: Environmental And Earth Sciences, Pollution Keywords: wastewater; river water; groundwater; migration species; bottom sediments; modeling
Online: 4 May 2023 (08:36:06 CEST)
The development of mineral deposits causes changes that are comparable to natural exogenous geological processes, and in local areas of intensive mining activity prevail over them. In this article, a diamond deposit is selected, developed by quarries of great depth, and a forecast is made of the impact of drainage water discharge on changes in the composition of surface water and bottom sediments during the entire period of development of the deposit. Modeling was per-formed according to various scenarios, taking into account changes in the total dissolved solids of groundwater from 0.5 to 21.7 g/kg H2O. Thermodynamic calculations were carried out using the HCh software package. The role of dissolved organic carbon in the migration of chemical elements and the effect of DOC on the precipitation of chemical elements from mixing solutions is given. It has been established that fulvic acid completely binds to Fe in the Fe(OH)2FA– complex in all types of natural waters and under all mixing scenarios. With humic acid, such a sharp competitive complex formation does not occur. It is distributed among the various elements more evenly. It was determined that the mass of precipitating iron in the presence of DOC decreases by 18-27%, and its precipitation in winter is more intense. In contrast to Fe, precipitation of Ca, Mg, and C from solution with DOC is higher in summer, and there are more of them in solution in winter. This study contributed to a better understanding of the behavior of heavy metals in surface waters and sediments under anthropogenic pressures in order to improve the sustainable management of water resources in the face of anthropogenic activities.
REVIEW | doi:10.20944/preprints202112.0261.v1
Subject: Environmental And Earth Sciences, Environmental Science Keywords: Africa; Biodiversity; Groundwater Resources; Integrated Watershed Management; River Basin
Online: 16 December 2021 (08:10:06 CET)
Human activities mostly impact the trend and direction of surface water, groundwater, and other river basin resources in the watershed in Africa. Human activities influence river flows and the water quality at both highlands and lowlands. A watershed is indeed a conserved area of land that collects rain and snow and empties or penetrates into ground water sources. The act of managing the activities around the watershed is the Integrated Watershed Management while considering the social, economic, and environmental issues, as well as community interests to manage water resources sustainably. These watersheds, river basins, and groundwater resources provide important services for communities and biodiversity. This paper reveals that the best way to protect groundwater resources is on a watershed basis using IWM. This technique enables us to handle a variety of concerns and objectives while also allowing us to plan in a complicated and uncertain environment. IWM involves cooperation and participation from a wide range of community interests and water users, including municipalities, companies, people, agencies, and landowners, for stakeholders' input to be successful. All of the strategies and plans are produced concerning one another, as well as the overall conditions of the watershed, local land uses, and specific issues.
ARTICLE | doi:10.20944/preprints202104.0393.v1
Subject: Engineering, Civil Engineering Keywords: streamflow; dynamic land-use change; ANN; SWAT; Dabus river
Online: 14 April 2021 (17:40:27 CEST)
Based on the recorded watershed characteristics, the future conditions on the basin system can be predicted using a different method. In this study, dynamic land-use change and its impacts on the streamflow for the Dabus watershed were predicted using ANN-CA based method. The model performance for accurate prediction of the future land-use change on the Dabus River watershed has been checked by validation of the simulated value with the actual value, hence the overall kappa value (k) = 0.83 for the simulated 2016-LULC validated with actual 2016-LULC. Then, 2026-LULC was predicted based on the 2004 and 2009-LULC. The streamflow for the case of 2004 and 2009-LULC has been simulated using the SWAT model. The value of NSE = 0.87 and 0.90 was attained during validation of simulated streamflow for 2004 and 2009-LULC data cases, respectively. The agreement of simulated value of streamflow with the observed data is indicated as R2 = 0.91 and 0.96 for 2004-LULC and 2009-LULC. The effects of the dynamic land-use change on streamflow for the predicted land use(2026-LULC) catchment were evaluated by T-test analysis. Hence, T-stat =0.04 and -0.002 in the case of simulated streamflow used 2004-LULC and 2009-LULC, respectively compared with simulated value using 2026-LULC.
ARTICLE | doi:10.20944/preprints202009.0691.v1
Subject: Engineering, Civil Engineering Keywords: water allocation; planning; river/reservoir systems; water availability modeling
Online: 28 September 2020 (16:55:27 CEST)
Effective water resources management requires assessments of water availability within a framework of complex institutions and infrastructure employed to manage extremely variable stream flow shared by numerous often competing water users and diverse types of use. The Water Rights Analysis Package (WRAP) modeling system is fundamental to water allocation and planning in the state of Texas in the United States. Integration of environmental flow standards into both the modeling system and comprehensive statewide water management is a high priority for continuing research and development. The public domain WRAP software and documentation are generalized for application any place in the world. Lessons learned in developing and implementing the modeling system in Texas are relevant worldwide. The modeling system combines: (1) detailed simulation of water right systems, interstate compacts, international treaties, federal/state/local agreements, and operations of storage and conveyance facilities; (2) simulation of river system hydrology; and (3) statistical frequency and reliability analyses. The continually evolving modeling system has been implemented in Texas by a water management community that includes the state legislature, planning and regulatory agencies, river authorities, water districts, cities, industries, engineering consulting firms, and university researchers. The shared modeling system contributes significantly to integration of water allocation, planning, system operations, and research.
ARTICLE | doi:10.20944/preprints202002.0428.v1
Subject: Engineering, Civil Engineering Keywords: small hydropower plant; river flow; seasonal forecast; energy production
Online: 28 February 2020 (12:15:43 CET)
The operation feasibility of small hydropower plants in mountainous sites is subjected to the run-of-river flow which is also depending on a high variability in precipitation and snow cover. Moreover, the management of this kind of systems has to be performed with some particular operation conditions of the plant (e.g. turbine minimum and maximum discharge) but also some environmental flow requirements. In this context, a technological climate service is conceived in tight connection with end users, perfectly answering the needs of the management of small hydropower systems in a pilot area, and providing forecast of river streamflow together with other operation data. This paper presents an overview of the service but also a set of lessons learnt related to features, requirements and considerations to bear in mind from the point of view of climate services developers. In addition, the outcomes give insight into how this kind of services could change the traditional management (normally based on the past experience), providing a probability range of future river flow based on future weather scenarios according to the range of future weather possibilities. This highlights the utility of the co-generation process to implement climate services for water and energy fields but also that seasonal climate forecast could improve the business as usual of this kind of facilities.
ARTICLE | doi:10.20944/preprints201912.0038.v1
Subject: Biology And Life Sciences, Immunology And Microbiology Keywords: Naegleria spp.; free-living amoeba; PCR; Monjolinho River; Brazil
Online: 4 December 2019 (04:27:21 CET)
The genus Naegleria, of free-living amoeba (FLA) group, has been investigated mainly due to its human health impact resulting in deadly infections and their worldwide distribution on freshwater systems. Naegleria fowleri, colloquially known as the “brain-eating amoeba”, is the most studied Naegleria species because it causes Primary Amoebic Meningoencephalitis (PAM) of high lethality. The assessment of FLA biodiversity is fundamental to evaluate the presence of pathogenic species and the possibility of human contamination. However, the knowledge of FLA distribution in Brazil is unknown, and to rectify this situation we present a research on identifying Naegleria spp. in the Monjolinho River, as a model study. The river is a public Brazilian freshwater source that crosses the city of São Carlos. Five distinct sampling sites were examined through limnological features, trophozoites culturing and PCR against internal transcribed spacers (ITS) regions and 5.8S rRNA sequence. The results identified N. philippinensis, N. canariensisi, N. australiensis, N.gruberi, N. dobsoni sequences, as well as a Vahlkampfia sequence. The methodology delineated here represents the first Brazilian Naegleria spp. study on a freshwater system. Our result stresses the urgency of a large scale evaluation of the presence of free-living amoebas in Brazil.
ARTICLE | doi:10.20944/preprints201910.0267.v1
Subject: Engineering, Civil Engineering Keywords: mediterranean region; river connectivity; fishway assessment; motivation; ascent ability
Online: 23 October 2019 (09:40:48 CEST)
Endemic freshwater fish from semiarid environments are among the most threated species in the world due to the water overexploitation and habitat fragmentation problems. Stepped or pool-type fishways are used worldwide to reestablish longitudinal connectivity and mitigate fish migration problems. Many of them are being installed or planned in rivers of semiarid environments, however, very few studies about fish passage performance through pool-type fishways has been carried out to date on these regions. The present work focuses on the passage performance of two potamodromous cyprinids endemic of these regions, with different ecological and swimming behavior: southern Iberian barbel (Luciobarbus sclateri) and Iberian straight-mouth nase (Pseudochondrostoma polylepis), in two of the most common types of stepped fishways: vertical slot and submerged notch with bottom orifice fishways. Experiments were carried out during the spawning season in the Segura River (South-Eastern Spain), using a PIT tag and antennas system. Ascent success was greater than 80%, with a median transit time lower than 17 minutes per meter of height in all trials and for both species and fishway types. Results show that both types of fishways, if correctly designed and built, provide interesting alternatives for the restoration of fish migration pathways on these regions.
ARTICLE | doi:10.20944/preprints201910.0096.v1
Subject: Environmental And Earth Sciences, Water Science And Technology Keywords: Rainfall-runoff model; large-scale river basins; calibration; validation
Online: 9 October 2019 (10:16:32 CEST)
In this work a modified version of the well-known Simple Water Balance (SWB) model, comprising here three parameters instead of one, was used. Although simple, the model was tested in large-scale river basins in east-central Greece, upstream two hydrometric stations. The available historic runoff records comprised 19 hydrologic years each, on a monthly basis. Thirteen among them were used for calibrating the model, whereas the six subsequent, for validating it. Two different efficiency criteria were used as a measure of performance of the modified model. Their values, calculated for both calibration and validation stages, were close and relatively high. Thus, keeping in mind both the size and complexity of the river basins studied, one can conclude that the modified model, despite its simplistic concept and lumped form, fits satisfactorily the historic runoff series.
ARTICLE | doi:10.20944/preprints201801.0151.v1
Subject: Environmental And Earth Sciences, Environmental Science Keywords: climate change; GR2M; hydrologic modeling; transboundary river; West Africa
Online: 17 January 2018 (11:09:07 CET)
In the context of climate change in West Africa characterized by a reduction of precipitation, this study was conducted to evaluate the impact of climate change on water resources from now to the end of the 21st century in the transboundary watershed of the Sassandra River shared by Guinea and Côte d’Ivoire. Historical and future climate (Representative Concentration Pathways or RCPs 4.5 and 8.5 scenarios) data were projected with the model. The Abdus Salam ICTP RegCM4 was used. The hydrological modeling of the river basin was carried out with the conceptual hydrological model, GR2M. This model is a monthly time steps model that allows the assessment of the discharge of the Sassandra River for each climate scenario according to the 2030 (2021–2040), 2050 (2041–2060), 2070 (2061–2080), and 2090 (2081–2100) horizons. The results showed a reduction of the annual discharge when compared to the baseline (1961–1980). For the RCP 4.5, the observed values went from –1.2% in 2030 to –2.3% in 2070 and rose to –2.1% in 2090. Concerning the RCP 8.5, we saw a variation from –4.2% to –7.9% in the 2030 and 2090 horizons, respectively. With the general decrease of rainfall in West Africa, it is appropriate to assess the impact on water resources on the largest rivers (Niger, Gambia, and Senegal) that irrigate the Sahelo-Saharian zone.
ARTICLE | doi:10.20944/preprints201712.0033.v1
Subject: Environmental And Earth Sciences, Environmental Science Keywords: river; restoration; ecosystem; management; water framework directive; ecosystem services
Online: 6 December 2017 (06:57:11 CET)
The purpose of the present research was to analyze the available data on river restoration projects. As the framework of our study, we conducted a structured international survey. We asked selected entities and experts from among those responsible for river restoration in European countries about the details and costs of European Union river restoration projects. We examined 119 river restoration projects that were implemented in Europe between 1989 and 2016; some of the projects were still ongoing. We observed that the number of river restoration projects has been increasing since 1989, which expresses society’s growing interest in improving the quality of aquatic environments. We revealed that 56% of these European river restoration projects have been implemented by dedicated entities and stakeholders, not as part of any structured, larger-scale river restoration policy; this indicates that most European countries do not have integrated plans for river restoration. Our analysis showed that 52% of the projects analyzed have been designed and implemented without the participation of local stakeholders. It also showed that the budgets for river restoration projects did not differ significantly across various time horizons from 1981 to 2016. In our study, the average cost of restoring 1 ha of an average European river was 310 000 EUR (or 195 000 EUR if 4 outlying values are excluded). Considering these projects’ permanent assets and including their amortization, for European river systems, we calculated the average unit price of a river restoration’s value in terms of ecosystem meta-service to be 7 757 EUR · ha-1 · year-1 (4 875 EUR · ha-1 · year-1 if 4 outlying values were excluded).
ARTICLE | doi:10.20944/preprints201706.0117.v1
Subject: Environmental And Earth Sciences, Remote Sensing Keywords: multi-temporal; seasonal; vegetation; palaeo-river; Indus civilisation; archaeology
Online: 27 June 2017 (04:41:04 CEST)
Remote sensing has considerable potential to contribute to the identification and reconstruction of lost hydrological systems and networks. Remote sensing-based reconstructions of palaeo-river networks have commonly employed single or limited time-span imagery, which limits their capacity to identify features in complex and varied landscape contexts. This paper presents a seasonal multi-temporal approach to the detection of palaeo-rivers over large areas based on long-term vegetation dynamics and spectral decomposition techniques. The use of multi-temporal data has allowed the overcoming of seasonal cultivation patterns and long-term visibility issues related to crop selection, large-scale irrigation and land use patterns. The application of this approach on the Sutlej-Yamuna interfluve (northwest India), a core area for the Bronze Age Indus Civilisation, has enabled the reconstruction of an unsuspectedly complex palaeo-river network comprising more than 8000 kms of palaeo-channels. It has also enabled the definition of the morphology of these relict courses, which provides insights into the environmental conditions in which they operated. These new data will contribute to a better understanding of the settlement distribution and environmental settings in which this, often considered riverine, civilisation operated.
ARTICLE | doi:10.20944/preprints201703.0010.v1
Subject: Environmental And Earth Sciences, Atmospheric Science And Meteorology Keywords: size distribution; OC; EC; seasonal variation; Yangtze River Delta
Online: 1 March 2017 (16:59:27 CET)
In order to investigate the size distributions and seasonal variations of carbonaceous aerosols (OC and EC), the carbonaceous species were collected and then analyzed by using a 9-stage Anderson-type aerosol sampler and DRI Model 2001A Thermal/Optical Carbon Analyzer on the typical industrial city Nanjing in Yangtze River Delta, China in the summer, autumn and winter of 2013 and spring of 2014. OC, EC, SOC and POC exhibited obvious seasonal variations, with the highest level in winter (39.1±14.0, 5.7±2.1, 23.6±11.7 and 14.1±5.7 μg•m-3) and the lowest level in summer (20.6±6.7, 3.3±2.0, 12.2±3.8 and 8.4±4.1 μg•m-3), and were mainly centralized in PM1.1 in four seasons. The concentrations of OC in PM1.1 varied in the order of winter > autumn > spring > summer, while EC ranked in the order of autumn > winter > summer > spring. In the PM1.1-2.1 and PM2.1-10, the concentrations of OC and EC decreased in the sequence of winter > spring > autumn > summer. The size spectra of OC, EC and SOC had bimodal distributions in four seasons, except for EC with four peaks in summer. The size spectra of POC varied greatly with seasons, exhibiting bimodal distribution in winter, trimodal distribution in spring and summer, and four peaks in autumn. The OC/EC ratios were 7.0, 6.3, 7.6 and 6.9 in spring, summer, autumn and winter, respectively, which demonstrated the abundance of secondary organic aerosols in Nanjing. The sources of carbonaceous aerosol varied significantly with seasons, and were dominated by vehicle exhaust, coal and biomass burning in PM2.1, and dominant by dust, coal and biomass burning in PM2.1-10.
ARTICLE | doi:10.20944/preprints202309.0809.v1
Subject: Environmental And Earth Sciences, Geography Keywords: NEX-GDDP-CMIP6; extreme precipitation; climate change; Huaihe River Basin
Online: 13 September 2023 (09:52:52 CEST)
This research analyses extreme precipitation events in the Huaihe River Basin in China, a densely populated region with a history of human settlements and agricultural activities. This study aims to explore the impact of extreme precipitation index changes and provide decision-making suggestions for flood early warning and agricultural development in the Huaihe River Basin. The study utilises the NEX-GDDP-CMIP6 climate models dataset and the daily value dataset (V3.0) from China's national surface weather stations to investigate temporal and spatial changes in extreme precipitation indices from 1960 to 2014 and future projections. At the same time, this study adopted the RclimDex model, Taylor diagram and Sen+Mann-Kendall trend analysis research methods to analyse the data. The results reveal a slight increase in extreme precipitation indices from northwest to southeast within the basin, except for CDD, which shows a decreasing trend. Regarding spatial, the future increase of extreme precipitation in the Huaihe River Basin will show a spatial variation characteristic that decreases from northwest to southeast. These findings suggest that extreme precipitation events are intensifying in the region. Understanding these trends and their implications is vital for adaptation strategy planning and mitigating the risks associated with extreme precipitation events in the Huaihe River Basin.
ARTICLE | doi:10.20944/preprints202308.0805.v1
Subject: Physical Sciences, Theoretical Physics Keywords: trends; extremes flow; extremes rainfall; Senegal river basin; upper basin
Online: 10 August 2023 (03:58:52 CEST)
This study aims to assess trends and significant changes in precipitation and river flow in the Senegal River basin and its upper basin over the period 1982-2021. Eight hydroclimate indicators, namely maximum river discharge (QMAX), standardized flow index, mean daily rainfall intensity index (SDII), maximum 5-day consecutive precipitation (RX5DAY), annual precipitation exceeding the 95th percentile (R95p), annual precipitation exceeding the 99th percentile (R99P), annual flows exceeding the 95th percentile (Q95p), and annual flows exceeding the 99th percentile (Q95p) were considered.. The modified Mann-Kendall test (MMK) was used to analyze trends in extremes while standard normal homogeneity and Pettit’s tests were employed to detect potential breakpoints in these trends. The results indicated an irregular precipitation pattern, with high values of extreme precipitation indices (R95p, R99p, SDII, and RX5DAY) in the southern part, while the northern part exhibits lower values. Inter-annual analysis revealed a significant increase in extreme precipitation events between 1982 and 2021, with a notable breakpoint around the years 2006 and 2007. This breakpoint marks a transition to a much wetter period starting from 2008. Regarding extreme flows, a significant increase was observed between 1982 and 2021. This study provides insights into past hydrological extremes in the study area and can serve as a basis for future research in this field.
ARTICLE | doi:10.20944/preprints202308.0450.v1
Subject: Environmental And Earth Sciences, Sustainable Science And Technology Keywords: pollution; Credit River; machine learning; graph neural networks; SHAP analysis
Online: 7 August 2023 (11:36:35 CEST)
In cold-climate regions, road salt is used as a de-icer for winter road maintenance. The applied road salt melts ice and snow on roads, being washed off through storm sewer systems into nearby urban streams, harming the freshwater ecosystem. Addressing the gap in the knowledge regarding the use of deep learning approaches for urban stream water quality forecasting, the present work discusses our implementation of a “Graph Neural Network” - “Sample and Aggregate” (GNN-SAGE) model for forecasting chloride concentrations in the Credit River in Ontario, Canada. The proposed GNN-SAGE is compared to other models, including a Deep Neural Network based transformer (DNN-Transformer) and a benchmarking persistence model for 6 hours forecasting horizon. Ac-cording to the results, the GNN-SAGE model surpasses other models in providing accurate predic-tions of chloride concentrations within the assessed prediction window. Also, a SHAP analysis provides insight into the variables that influence the model’s forecasting, showing the impact of the spatiotemporal neighbouring data from the network and the seasonality variables on the model’s result. The GNN-SAGE model shows potential for use in real-time forecasting of water quality in urban streams, aiding in the development of regulatory policies to protect the vulnerable freshwater ecosystems in urban areas.
ARTICLE | doi:10.20944/preprints202308.0049.v1
Subject: Biology And Life Sciences, Ecology, Evolution, Behavior And Systematics Keywords: Waterbirds; Zambezi River; Sikunga channel; Fish protected areas; functional Diversity
Online: 1 August 2023 (08:30:34 CEST)
Carnivorous waterbirds have been reported to enhance wetlands diversities, control pests, bio-indicators of ecological conditions, and act as indicators of potential disease outbreaks. They also provide important ecosystem services to indigenous communities residing along wetlands. Regardless of their importance, global waterbirds populations are declining. Despite their ecological contribution to wetlands functions and ecosystem services, piscivore waterbirds have been re-ported to compete with piscivorous fish and fishermen. The aim of this study was to compare piscivorous waterbirds species and functional diversity between fish protected areas (FPA) and non-fish protected area (NFPA) in two tributaries of Zambezi River in Namibia. We also measured the degree to which patterns of guild structure between piscivore waterbirds and fish were similar between FPA and non-FPA. Species diversities were determined by calculating the Shannon Diversity Index. We calculated taxonomic diversity, functional diversity and community-based trait diversity indices for each tributary. Generally, species diversities were not significantly different between FPA and NFPA (P > 0.05). However, all functional diversities indices calculated were significantly different between FPA an NFPA (P < 0.05 for all comparisons). This was partly due to food item, weight and movement type that were associated with each site.
ARTICLE | doi:10.20944/preprints202306.0594.v1
Subject: Environmental And Earth Sciences, Remote Sensing Keywords: SAR; Gravel-bed rivers; Morphodynamics; Flood dynamics; River bank erosion
Online: 8 June 2023 (05:00:07 CEST)
Remote sensing plays a central role in the assessment of environmental phenomena and has increasingly become a powerful tool for monitoring shorelines, rivers morphology, flood waves delineation and floods assessment. Optical based monitoring and characterization of river evolution at long time scales is a key tool in fluvial geomorphology. However, the evolution occurring during extreme events is crucial for the understanding of the river dynamics under severe flow conditions and requires the processing of data from active sensors to overcome cloud obstructions. This work proposes a cloud-based unsupervised algorithm for the intra-event monitoring of river dynamics during extreme flow conditions based on time series of Sentinel-1 SAR data. The method allows the extraction of multi-temporal series of spatially explicit geometric parameters at high time and spatial resolutions, linking them to the hydrometric levels acquired by reference gauge stations. Intra-event reconstruction of inundation dynamics has led to the estimation of the relationship between hydrometric level and wet area extension and the assessment of bank erosion phenomena. Time series of SAR acquisitions, provided by Copernicus Sentinel-1 satellites, were analyzed to quantify changes in the wet area of a reach of the Tagliamento river under different flow conditions. The algorithm, developed within the Python-API of GEE, first empowers the Sentinel-1 images with the hydrometric level, then involves radiometric slope correction and speckle noise filtering. The Otsu method is then used for image segmentation leading to a water and dry land binary classification. Results support many types of analysis about river dynamics, including morphological changes, floods monitoring and relief efforts and bio-physical habitat dynamics. The results encourage future advancements and applications of the algorithm, specifically exploring SAR data from ICEYE and Capella Space constellations, which offer significantly higher spatial and temporal resolutions compared to Sentinel-1 data.
TECHNICAL NOTE | doi:10.20944/preprints202209.0410.v1
Subject: Engineering, Civil Engineering Keywords: 2D floodplain modeling; HEC-RAS; River Renaturation; finite difference approximation
Online: 27 September 2022 (03:53:09 CEST)
River renaturation can be an effective management method for restoring the floodplain's natural capacity and minimizing the effects during high flow periods. A 1D-2D HEC-RAS model, in which the flood plain was considered as 2D and the main channel as 1D, was used to simulate flooding in the restored reach of the Spree River. When computing in this model, finite volume and finite difference approximations using the Preissmann approach are used for the 1D and 2D models, respectively. To comprehend the sensitivity of the parameters and model, several scenarios were simulated using different time steps and grid sizes. Additionally, dykes, dredging, and changes to the vegetation pattern have been used to simulate flood mitigation measures. The model predicted that flooding would occur mostly in the downstream portion of the channel in the majority of the scenarios without mitigation measures, whereas with mitigation measures, flooding in the floodplain would be greatly reduced. By preserving the natural balance on the channel's floodplain, the restored area needs to be kept in good condition. Therefore, mitigating measures that balance the area's economic and environmental aspects must be considered in light of the potential for floods.
ARTICLE | doi:10.20944/preprints202207.0092.v1
Subject: Social Sciences, Behavior Sciences Keywords: Heavy metals; Risk assessment; Source analysis; Surface sediment; Qinjiang River
Online: 6 July 2022 (08:57:28 CEST)
Heavy metals are toxic, persistent and non-degradable. After sedimentation and adsorption, they accumulate in water sediments. The aim of this study was to understand the heavy metal pollution of Qinjiang River sediments on the ecological environment and apportioning sources. The mean total concentrations of Mn, Zn, Cr, Cu, and Pb are 3.14, 2.33, 1.39, 5.79, and 1.33 times higher than the background values, respectively, except for the Co, Ni, and Cd, which are lower than the background values; Fe, Co, Ni, Cd, Cr, Cu, and Pb are all primarily in the residual state, while Mn and Zn are primarily in the acid-soluble and oxidizable states, respectively. Igeo, RI, SQGs and RAC together indicate that the pollution status and ecological risk of heavy metals in Qinjiang River sediments are generally moderate; among them, Fe, Co, Ni, Cd, Cr, and Pb are not harmful to the ecological environment of the Qinjiang River. Cu is not readily released because of its higher residual composition, depicting that Cu is less harmful to the ecological environment. Mn and Zn, as the primary pollution factors of the Qinjiang River, are harmful to the ecological environment. This heavy metal pollution in surface sediments of the Qinjiang River primarily comes from manganese and zinc ore mining. Manganese carbonate and its weathered secondary manganese oxide are frequently associated with a significant amount of residual copper and Cd, as a higher pH is suitable for the deposition and enrichment of these heavy metals. Lead-zinc ore and its weathering products form organic compounds with residual Fe, Co, Cr, and Ni, and their content is related to salinity. The risk assessment results of heavy metals in sediments provide an important theoretical basis for the prevention and control of heavy metal pollution in Qinjiang River.
Subject: Environmental And Earth Sciences, Atmospheric Science And Meteorology Keywords: river valley bottom; GIS; cost distance accumulation; groundwater dependent ecosystems
Online: 1 March 2021 (13:50:04 CET)
River valley bottoms have hydrological, geomorphological, and ecological importance and are buffers for protecting the river from upland nutrient loading coming from agriculture and other sources. They are relatively flat, low-lying areas of the terrain that are adjacent to the river and bound by increasing slopes at the transition to the uplands. These areas have under natural conditions, a groundwater table close to the soil surface. The objective of this paper is to present a stepwise GIS approach for the delineation of river valley bottom within drainage basins and use it to perform a national delineation. We developed a tool that applies a concept called cost distance accumulation with spatial data inputs consisting a river network and slope derived from a digital elevation model. We then used wetlands adjacent to rivers as a guide finding the river valley bottom boundary from the cost distance accumulation. We present results from our tool for the whole country of Denmark carrying out a validation within three selected areas. The results reveal that the tool visually performs well and delineates both confined and unconfined river valleys within the same drainage basin. We use the most common forms of wetlands (meadow and marsh) in Denmark's river valleys known as Groundwater Dependent Ecosystems (GDE) to validate our river valley bottom delineated areas. Our delineation picks about half to two-thirds of these GDE. However, we expected this since farmers have reclaimed Denmark's low-lying areas during the last 200 years before the first map of GDE was created. Our tool can be used as a management tool, since it can delineate an area that has been the focus of management actions to protect waterways from upland nutrient pollution.
ARTICLE | doi:10.20944/preprints202001.0371.v1
Subject: Environmental And Earth Sciences, Geophysics And Geology Keywords: Quaternary; Holocene; alluvial sediments; Sava River; gravels; morphometry; Zagreb; Croatia
Online: 30 January 2020 (14:48:11 CET)
Morphometric analysis of Holocene pebbles from the Sava River gravels, in Zagreb alluvial aquifer system (NW Croatia), revealed distribution of their shapes along 30 km long observed watercourse. Limestones, dolomites and sandstones are determined as major (> 4%), and effusive magmatics, cherts and tuffs as minor lithotypes of the pebbles (up to 4%). Their distributions indicate mainly distant Alpine provenance for carbonate (limestones and dolomites) pebbles and local input for sandstones and minor lithotypes, laterally from the Samoborska gora and Medvednica Mts. Carbonates have predominately disc and sphere shapes, implying also their mainly distant sources. Scattered distributions of pebble shapes (sphere, disc, blade and rod) for sandstones and minor lithotypes indicate multiple sources, some of them probably local. Original sedimentary environments for main pebble lithotypes are tentatively interpreted from their flatness ratios, indicating predominant lake shore environments, followed by moraine and riverbed.
ARTICLE | doi:10.20944/preprints201908.0294.v1
Subject: Physical Sciences, Mathematical Physics Keywords: time series; Colorado River; water supply; cross-validation; decadal prediction
Online: 28 August 2019 (11:32:10 CEST)
The future of the Colorado River water supply (WS) affects millions of people and the U.S. economy. A recent study suggested a cross-basin correlation between the Colorado River and its neighboring Great Salt Lake (GSL). Following that study, the feasibility of using the previously developed multi-year prediction of the GSL water level to forecast the Colorado River WS was tested. Time-series models were developed to predict the changes in WS out to 10 years. Regressive methods and the GSL water level data were used for the depiction of decadal variability of the Colorado River WS. Various time-series models suggest a decline in the 10-year-averaged WS since 2013 before starting to increase around 2020. Comparison between this WS prediction and the WS projection published in a 2012 government report (derived from climate models) reveals a widened imbalance between supply and demand by 2020. Further research to update similar multi-year prediction of the Colorado River WS is needed. Such information could aid in management decision making in the face of future water shortages.
ARTICLE | doi:10.20944/preprints201905.0336.v1
Subject: Engineering, Civil Engineering Keywords: secondary flow; cohesive; deposition; 2D numerical model; meandering; Yangtze River
Online: 28 May 2019 (11:10:24 CEST)
A conventional 2D numerical model is improved by incorporating three submodels to consider different effects of secondary flow and a module for cohesive sediment transport. The model is applied to a meandering reach of Yangtze River to investigate secondary flow effects on cohesive sediment deposition, and a preferable submodel is selected based on the flow simulation results. Sediment simulation results indicate that the improved model predictions are in better agreement with the measurements in planar distribution of deposition as the increased sediment deposits caused by secondary current on the convex bank have been well predicted. Secondary flow effects on predicted amount of deposition become more obvious during the period when the sediment load is low and velocity redistribution induced by the bed topography is evident. Such effects vary with the settling velocity and critical shear stress for deposition of cohesive sediment. The bed topography effects can be reflected by the secondary flow submodels.
ARTICLE | doi:10.20944/preprints201712.0131.v1
Subject: Environmental And Earth Sciences, Geophysics And Geology Keywords: 1D modelling; large rivers; morphodynamic equilibrium; river concavity; bottom fining
Online: 19 December 2017 (07:15:22 CET)
To date, several different approaches are available to study sediment dynamics at reach or watershed scale, based on very different hypothesis. One of such assumptions, the so-called “morphodynamic equilibrium hypothesis” is becoming little unpopular for its embedded simplifications. The aim of this work is to demonstrate how this approach proves yet effective in modelling landscape morphodynamics at the watershed scale, for what concerns the longitudinal profile of a river and the sedimentary aspects. The application of a 1-D model based on the equilibrium hypothesis has been implemented for several large rivers worldwide. Geomorphological parameters have been analysed, which describe the evolution of longitudinal profile (concavity) and sediments characteristics (aggrading and fining), and the results show a reasonably good correspondence with qualitative estimation of the same parameters. At the scale of analysis and for the chosen systems, which show high inertia to geomorphological changes likely owing to their longitudinal extension, the model can detect where the present conditions reflect a big disturbance to the “natural equilibrium” thus allowing water managers to identify present issues to be addressed.
ARTICLE | doi:10.20944/preprints201708.0030.v1
Subject: Environmental And Earth Sciences, Environmental Science Keywords: Joint entropy; NDVI; temperature; precipitation; groundwater depth; Hei River basin
Online: 8 August 2017 (08:42:54 CEST)
Terrestrial vegetation dynamics are closely influenced by a multitude of factors. This study investigated the relationships between vegetation patterns and their main influencing factors. The joint entropy method was employed to evaluate the dependence between normalized difference vegetation index (NDVI) and coupled variables in the middle reaches of Hei River basin. Based on the spatial distribution of mutual information, the whole study area was divided into five sub-regions. In each sub-region, nested statistical models were applied to model the NDVI on the grid and regional scales, respectively. Results showed that the annual average NDVI increased with a rate of 0.005/a in recent 11 years. In the desert regions, the NDVI increased significantly with an increase in precipitation and temperature, and high accuracy of retrieving NDVI model was obtained by coupling precipitation and temperature, especially in sub-region I. In the oasis regions, groundwater was also an important factor driving vegetation growth, and the rise of groundwater level contributed to the growth of vegetation. However, the relationship was weaker in artificial oasis regions (sub-region III and sub-region V) due to the influence of human activities, such as irrigation. The overall correlation coefficient between the observed NDVI and modeled NDVI was observed to be 0.97. Outcomes of this study are suitable for ecosystem monitoring, especially under the realm of climate change. Further studies are necessary and should consider more factors, such as runoff and irrigation.
ARTICLE | doi:10.20944/preprints201610.0079.v1
Subject: Engineering, Civil Engineering Keywords: river confluence; stage-discharge relationship; hydrodynamic influence; backwater; flow separation
Online: 19 October 2016 (12:31:32 CEST)
An accurate assessment of the stage-discharge relationship in open channel flows is necessary and important to the design and management of hydraulic structures and engineering in practical hydrosystems such as rivers and streams. While the flow structures and patterns at open channel junctions are interesting and have been widely studied in the literature, this paper focuses further on the effect of flow junctions on stage-discharge relationship at mountain river confluences. In this study, both the flume and physical model experiments are designed and performed carefully to test and analyze the complex flow structures and characteristics at river confluences with different configurations and hydraulic conditions. The impacts of the flow junctions on the traditional stage-discharge relationship are analyzed in this study. The results of this study are discussed in the paper for the understanding of flow structures at flow junctions and the design and management of hydraulic structures in river engineering.
ARTICLE | doi:10.20944/preprints202311.0561.v1
Subject: Biology And Life Sciences, Aquatic Science Keywords: European Anguilla; Brown trout; river pollution; histopathological biomarkers; liver; blood; spleen
Online: 9 November 2023 (06:57:26 CET)
The aim of the present study, was to evaluate the wild freshwater fish health status using a vast array of biomarkers as predictive factor of pollutant exposure. European eel (Anguilla anguilla) and Brown trout (Salmo trutta fario), resident in rivers with different degree of pollution in the South of Italy (Picentino river with good environmental quality and Tusciano river with low environmental quality), were examined using biometric parameters, histopathological and immunohistochemical biomarkers to evaluate the health status and a possible correlation with the water quality. Several alterations identified in the liver positively correlated with water and soil pollutants were: hemorrhage (P≤0.05), cytoplasmic vacuolization (P≤ 0.01), hemosiderosis (P≤0.05), irregular arrangement of hepatocytes (P≤ 0.01), lipid accumulation (P≤0.05), necrosis (P≤ 0.01), cellular hyperplasia (P≤0.05), leukocyte infiltration (P≤ 0.01) and melanomacrophages centers (MMC) (P≤ 0.01). In the spleen, only hemosiderosis correlated with water and soil pollutants (P≤ 0.05). The inflammatory biomarker tumor necrosis factor α (TNFα) and ciclooxigenase 2 (COX2) responded to the environmental pollution, as well as the oxidative stress biomarkers superoxide dismutase (SOD) and 8-Hydroxy-2'-deoxyguanosine (8-OHdG). Erythrocytic nuclear abnormalities and erythrocytic cellular abnormalities were found significantly higher in the blood of both Europen eel (P<0.0001) and Brown trout (P <0.001) in the Tusciano river with respect to the Picentino river. Taken together, these results outline the need to increase the number of suitable biomarkers to assess fish health and reinforce the importance to employ additional biomarkers in biomonitoring programs which can be applied to evaluate the water quality and environmental risk assessment around the world
ARTICLE | doi:10.20944/preprints202311.0371.v1
Subject: Environmental And Earth Sciences, Environmental Science Keywords: ecosystem service; conservation planning; trade-offs; protected areas; Yangtze River Basin
Online: 7 November 2023 (11:38:36 CET)
Biodiversity has long been the main objectives in conservation planning while protecting ecosystem services are rarely concerned with. Protecting ecosystem services are gradually recognized by researchers to be included in conservation planning as its significant benefits to human beings. Currently, the most commonly used protecting strategies only focused on high-value areas so that not all the valuable areas would be protected. Furthermore, there are correlation of trade-off and synergy between ecosystem services, aiming at protecting one ecosystem service may have to sacrifice the conservation effectiveness for others. To ensure all the ecosystem services are adequately protected, spatial explicit relations between all the paired ecosystem services were identified via the calculation of Local Moran’s I, a local scale relationship between ecosystem services were defined and they were classified into 5 kinds of cluster. To alleviate the conflict solutions for multiple ecosystem services goals, we used methodology of Systematic Conservation Planning to identify the priority areas for ecosystem service protection, which act the plan with principles of representativeness, complementarity and persistence. By setting scenarios of optimizing each and all the ecosystem services at the target level from 10% to 90%, we found that positive correlation between each of the 4 ecosystem services occupied large areas in the Yangtze River Basin and all the high-value areas were not congruence in spatial distributions. The optimal conservation spatial pattern showed that the priority areas were quite different when the target level was low. Our results implicated that an integrated conservation planning of achieving objectives of all the ecosystem services is more efficient than superposing multiple planning time after time.
ARTICLE | doi:10.20944/preprints202309.1611.v1
Subject: Environmental And Earth Sciences, Ecology Keywords: methane emission; littoral lake; lotus; carbon sink; greenhouse gases; Yangtze River
Online: 25 September 2023 (06:04:52 CEST)
Freshwater lakes represent a potential source of methane (CH4) to the atmosphere. However, the CH4 emission contribution to the total emission in the littoral zones of lakes, especially emergent macrophytes (e.g., lotus), are poorly known. Lotus, has been cultivated in almost all provinces in China, is not only an aquatic plant but also a kind of vegetables. Two sampling zones (lotus plant and open water) were established in the lake of the middle reaches of Yangtze River. The CH4 emission was measured using a floating opaque chamber and gas chromatography between April to December of the years 2021 and 2022. The results indicated that the flux of CH4 emissions ranged from 0.10 to 59.75 mg m-2 h-1, with an average value of 5.61 mg m-2 h-1 in the open water, while ranged from 0.19 to 57.32 mg m-2 h-1, with an average value of 17.14 mg m-2 h-1 in the lotus plant zone. The maximal CH4 emissions occurred in July and August for the open water, which was highly related to the air and water temperature; whereas it happened in September for the lotus plant zone, due to the fresh organic matter inputting to sediments, CH4 transportation by lotus plant, high soil organic carbon content, and the lower dissolved oxygen concentration. Considering the carbon emissions (both CH4 and CO2) and plant productivity, although the greater CH4 emission occurring in lotus plant zone, it could still represent a potential carbon sink (213 g m-2 yr-1), compared to the open water.
ARTICLE | doi:10.20944/preprints202307.1568.v1
Subject: Environmental And Earth Sciences, Geography Keywords: runoff; sediment; sediment concentration; sediment inflow coefficient; variation; reservoir; Jinsha River
Online: 25 July 2023 (04:17:45 CEST)
For the purpose of clean energy hydropower development, the construction of reservoirs has been continuously promoted in the Jinsha River basin for many years, and how the reservoirs affect the water and sediment process is a very necessary topic to study. This study is based on the gauged water and sediment data (span from the 1960’s to 2020) at Shigu, Panzhihua, and Xiangjiaba stations downstream located in the trunk channel of the river, and uses Mann-Kendall trend test method and double cumulative curve method to comprehensively judge the variation trends of runoff and suspended sediment load and reveal their credible mutation years. The linear regression method is used to reveal the variation characteristics of the relationship between water and sediment before and after the abrupt change years. The results show that the variations in runoff at Shigu and Panzhihua stations have significant and relatively obvious increasing trends, respectively, and that at Panzhihua station has a mutation year of 1985. The runoff at Xiangjiaba Station slightly increased but not significantly. The variation of suspended sediment load showed a temporal and spatial differentiation. The variation of sediment discharge at Shigu Station showed an increasing trend with a mutation year of 1997. For Panzhihua Station, it showed an increasing trend before 1998, but has significantly decreased since 1998. The fluctuation of sediment transport at Xiangjiaba Station was significant before 1998, but the trend is unclear. In the period of 1998−2020, it showed a significant decreasing trend, especially since 2013, when the mean annual suspended sediment load only accounted for 0.61% of its multi-year average. The variations of mean annual sediment concentration and sediment inflow coefficient at the hydrological stations is consistent with the variation trend of sediment transport. Before 2013, the correlation between water and sediment was strong, but thereafter it was extremely weak. The two sudden years of 1998 and 2013 are consistent with the year when large reservoirs were built in the river basin. The construction of large reservoirs and their large amount of sediment retention are the key reasons for the sudden changes in the water-sediment relationship and the sharp decrease in sediment transport in the downstream reach of the reservoir dam. The climate and underlying surface changes in the study area are not significant, and their impact on the water and sediment processes in the watershed is limited.
ARTICLE | doi:10.20944/preprints202307.1311.v1
Subject: Environmental And Earth Sciences, Other Keywords: Nakdong River estuary; shoreline survey; discharge; sediment; erosion; bathymetry; sandbar; topography
Online: 19 July 2023 (09:52:46 CEST)
Changes in coastal topography can affect the ecological environment and marine industries. In this study, we analyzed the patterns and causes of changes in shoreline and undersea topography in the Nakdong River estuary in the southeast of South Korea using depth and shoreline surveys of the estuary, as well as data on discharge, suspended sediments, and precipitation in the Nakdong River basin. The results showed that erosion and sedimentation occurred repeatedly owing to complex factors such as the discharge of the estuary and invasion by open sea waves. However, no clear unilateral trend was observed. Unlike previous survey data, a large amount of erosion occurred in the second half of 2020. Previously, sedimentation was the main process, but erosion occurred rapidly, which was observed in the summer of 2020 when the erosion was three times higher than that in other periods owing to the severe rainy season and torrential rains for over a month. In addition, regarding the flow rate and force of the river water outflow, the amount of discharge increased rapidly, causing erosion. Moreover, a strong typhoon in the summer of 2020 affected the topography of the estuary.
ARTICLE | doi:10.20944/preprints202307.0625.v1
Subject: Engineering, Civil Engineering Keywords: Intuitionistic fuzzy sets; TOPSIS; stakeholder’s involvement; water resources management; Laspias River.
Online: 10 July 2023 (11:41:38 CEST)
Βottom-up management in catchment scale is deemed as the determinant way to avoid the conflict of the water users through the participation of stakeholders, strategy co-shaping and solutions co-creation. Water management cannot be one-dimensional but demands cross sectoral coop-eration. Usually, the difficulty lies in proper stakeholder training and their opinion inclusion, using a quantifiable manner in water management. The Laspias River watershed occupies an area of 221.8 km2, belonging to the River Basin District of Thrace and it is characterized by intense agricultural and industrial activity. Complying with the augmented water needs and pollution loads by respecting stakeholders’ opinion, this research aims to utilize a hybrid intuitionistic fuzzy multi-criteria-based methodology. It is a common difficulty to deal with supplier selection in resources management since it is a typically decision-making problem encompassing multiple (several conflicting) criteria, on which stakeholder’s opinions are usually imprecise and in a rather qualitative form. Therefore, the proposed method provides the mathematical tool to move into more comprehensive decisions with the public involvement. The weights are produced based on the stakeholder’s opinion. The alternatives’ ranking is achieved based on the fuzzified intuition-istic version of Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) and problems’ mitigation solutions’ hierarchy is achieved.
ARTICLE | doi:10.20944/preprints202306.1316.v1
Subject: Environmental And Earth Sciences, Water Science And Technology Keywords: Concentration Characteristics; Health Risk Assessment; Heavy Metals; Nandong; Underground River Watershed
Online: 19 June 2023 (07:46:53 CEST)
Wastes from social economic activities had great impact on water quality thereby limiting water usability for domestic purposes. Sewages discharge from people activities, usually consist of undesirable concentrations of soluble chemicals that infiltrate into the surrounding surface and underground water, and then constitute health risk to the populace. In order to investigate the concentration characteristics and health risk for the local residents in Nandong Underground River Watershed (NURW), eleven common heavy metals in the water body analysis were conducted. Health risk assessment (HRA) was taken to analyze eleven heavy metals of 84 water samples from surface and underground waters in NURW: 36 samples underground water and 48 samples surface water. Our results showed that the heavy metals concentration order is that of Fe > Al > Mn > Zn > As > Cd > Pb > Cr > Ni > Cu > Hg. Correlation analysis indicates that these eleven metal elements have certain similarity on material source and migration transformation. The health risks for local residents exposed to metal elements in the water of NURW mainly from carcinogenic risk (10−6～10−4 a−1) through drinking way, and the health risk of heavy metals exposed to children through drinking way was much higher than adults. The maximum exposing health risks of Cr in both underground and surface water were higher than the recommendation standard (5.0×10-5 a-1) from ICRP, and all the values over the standard (5.0×10-6 a-1) recommended by the Swedish Environmental Protection Agency and the Dutch Ministry of Construction and Environment and the British Royal Society. The results of health risk assessment shows that Cr in the water of NURW was the mainly source of carcinogenic risk for the local residents, following by Cd and As. Consequently, it is necessary to control the three carcinogenic metals when the water was used as drinking water source.
ARTICLE | doi:10.20944/preprints202306.0269.v1
Subject: Medicine And Pharmacology, Tropical Medicine Keywords: Schistosoma mekongi; LAMP; Reservoir Animal; Domestic animal; Lao PDR; Mekong River;
Online: 5 June 2023 (08:25:55 CEST)
The prevalence of Schistosoma mekongi in humans in the Lao People’s Democratic Republic (Lao PDR) has been relatively well monitored and has decreased due to effective interventions such as preventative chemotherapy with mass drug administration of praziquantel and community awareness programs. However, the prevalence among potential domestic reservoir animals remains broadly unclear, except for a few villages in the endemic area. Therefore, we conducted S. mekongi surveys for the domestic animals that had contact with Mekong River water. We conducted a cross-sectional study of the domestic animals in the seven sentinel villages in the Khong and Mounlapamok Districts of Champasak Province in southern Lao PDR in 2018 by random sampling with a statistically reliable sample size. Stool samples of the five predominant domestic animal species, cattle (n = 160), pig (n = 154), buffalo (n = 149), dog (n = 143), and goat (n = 85), were collected and examined by experienced laboratory technicians using parasitological FECT method and the LAMP technique. The microscopic analysis did not detect any eggs of S. mekongi in the stool samples of any animal species. However, S. mekongi DNA was detected by the LAMP test in dog stool samples (0.7%; 1/143). Other helminth eggs were found during our microscopic analysis. These findings suggested that an intervention for S. mekongi infection should focus solely on human populations. However, periodic surveillance for S. mekongi infection among dogs should be conducted to monitor a possible resurgence of S. mekongi infection in the domestic animal population.
ARTICLE | doi:10.20944/preprints202209.0398.v1
Subject: Engineering, Civil Engineering Keywords: river discharge; hydro informatics; water resource; data-driven; deep learning; LSTM
Online: 26 September 2022 (11:30:24 CEST)
River flow prediction is a pivotal task in the field of water resource management during the era of rapid climate change. The highly dynamic and evolving nature of the climatic variables e.g., precipitation has a significant impact on the temporal distribution of the river discharge in recent days making the discharge forecasting even more complicated for diversified water-related issues e.g., flood prediction and irrigation planning. To predict the discharge, various physics-based numerical models are used using numerous hydrologic parameters. Extensive lab-based investigation and calibration are required to reduce the uncertainty involved in those parameters. However, in the age of data-driven predictions, several deep learning algorithms showed satisfactory performance in dealing with sequential data. In this research, Long Short-term Memory (LSTM) neural network regression model is trained using over 80 years of daily data to forecast the discharge time series up to 3 days ahead of time. The performance of the model is found satisfactory through the comparison of the predicted data with the observed data, visualization of the distribution of the errors and Root Mean Squared Error (RMSE) value of 0.09. Higher performance is achieved through the increase in the number of epochs and hyper parameter tuning. This model can be transferred to other locations with proper feature engineering and optimization to perform univariate predictive analysis and potentially be used to perform real-time river discharge prediction.
ARTICLE | doi:10.20944/preprints202110.0221.v1
Subject: Environmental And Earth Sciences, Environmental Science Keywords: river; forest; bog; permafrost; carbon; major ions; iron; colloids; trace element
Online: 15 October 2021 (08:59:43 CEST)
Assuming that climate warming in the WSL will lead to a northward shift of the forest and permafrost boundaries, a “substituting space for time” approach predicts an increase in concentration of DIC and labile major and trace elements and a decrease of the transport of DOC and low soluble trace metals in the form of colloids in the main stem of the Ob River. However, an unknown factor is the change in hydrochemistry of the largest southern tributary, the Irtysh River, which is impacted by permafrost-free steppe and forest-steppe zone. Overall, seasonally-resolved transect studies of large riverine systems of western Siberia are needed to assess the hydrochemical response of this environmentally-important territory to on-going climate change.
ARTICLE | doi:10.20944/preprints202108.0363.v1
Subject: Environmental And Earth Sciences, Environmental Science Keywords: Yukon River; sediment load; surface sediment plume; density underflow; MODIS image
Online: 17 August 2021 (10:48:38 CEST)
Sediment plumes, released to the Bering Sea from the delta front of the Yukon River, Alaska, are initiated mainly by glacier-melt sediment runoffs in the glacierized regions of the Yukon River drainage basin. The surface sediment plumes are extended around the fan-shaped Yukon River delta, which is followed by the northwestward dispersion. During continuous measure-ments of the Yukon River discharge and sediment load, behaviors of the sediment plumes were explored by shipboard observations in the Bering Sea offshore from the Yukon delta. At the high river sediment load of ca. 3000 kg/s, the plume partially plunged into the sea bottom layer. The plunging probably originated in the nepheloid-layer formation from the flocculation of river-suspended sediment, of which more than 90 %wt. is silt and clay (grain size d < 0.063 mm). In order to numerically obtain the area of the surface sediment plumes, a satellite image analy-sis was performed by using three near-infrared bands in MODIS/Aqua or MODIS/Terra. The plume area was significantly correlated (R2=0.735, p<0.01) to the sediment load averaged for the two days with time lags of 20 days and 21 days to the date of a certain satellite image. Hence, the dispersion of plume-suspended sediment appears to be controlled by the sediment runoff events in the Yukon River rather than the northward “Alaskan Coastal Water”.
ARTICLE | doi:10.20944/preprints202101.0357.v1
Subject: Environmental And Earth Sciences, Atmospheric Science And Meteorology Keywords: GRACE; GRACE-FO; TWS; hydroclimatic; drought; flooding; Nile River Basin; Africa
Online: 18 January 2021 (15:14:32 CET)
This research assesses the changes in the total water storage (TWS) during the twentieth century and their future projections in the Nile River Basin (NRB) via TWSA (TWS anomalies) records from GRACE (Gravity Recovery and Climate Experiment), GRACE-FO (Follow-On), data-driven-reanalysis TWSA and land surface model (LSM), in association with precipitation, temperature records, and standard drought indicators. The analytical approach incorporates the development of 100+ yearlong TWSA records using a probabilistic conditional distribution fitting approach by the GAMLSS (Generalized Additive Model for Location, Scale, and Shape) model. The drought and flooding severity, duration, magnitude, frequencies, and recurrence were assessed during the studied period. The results showed, 1- The NRB between 2002 to 2020 has transited to substantial wetter conditions. 2- The TWSA reanalysis records between 1901 to 2002 revealed that the NRB had experienced a positive increase in TWS during the wet and dry seasons. 3- The projected TWSA between 2021 to 2050 indicated slight positive changes in TWSA during the rainy seasons. The analysis of drought and flooding frequencies between 1901 to 2050 indicated the NRB has ~64 dry-years compared to ~86 wet-years. The 100+ yearlong TWSA records assured that the NRB transited to wetter conditions relative to few dry spells. These TWSA trajectories call for further water resources planning in the region especially during flood seasons. This research contributes to the ongoing efforts to improve the TWSA assessment and its associated dynamics for transboundary river basins. It also demonstrates how an extended TWSA record provides unique insights for water resources management in the NRB and similar regions.
ARTICLE | doi:10.20944/preprints202011.0299.v1
Subject: Environmental And Earth Sciences, Atmospheric Science And Meteorology Keywords: groundwater quality; extended SWAT model; water quality parameters; Athabasca River Basin
Online: 10 November 2020 (10:32:09 CET)
Groundwater is a vital resource for human welfare. However, due to various factors, groundwater pollution is one of the main environmental concerns facing. Yet, it is challenging to simulate groundwater quality dynamics due to the insufficient representation of nutrient percolation processes in the soil and Water Assessment Tool model. The objectives of this study were extending the SWAT module to predict groundwater quality. The results proved a linear relationship between observed and calculated groundwater quality considering No3 and TDS with R2, NSE and PBIAS values in the satisfied ranges, albeit underestimation and overestimation were observed due to limited data availability. These results highlight that nitrate and TDS concentrations and variability in groundwater may used as a tool in surface water quality that have to be assumed for designing adaptive management scenarios. Hence, extended SWAT model could be a powerful tool for future regional to global scale modelling of nutrient loads supporting effective surface and groundwater management.
ARTICLE | doi:10.20944/preprints201909.0057.v1
Subject: Engineering, Civil Engineering Keywords: HBV, GRACE, SMAP, ESA CCI SM v04.4, AMSR-E, Moselle River
Online: 5 September 2019 (10:14:35 CEST)
Although the complexity of physically based models continues to increase, they still need to be calibrated. In recent years, there has been an increasing interest in using new satellite technologies and products with high resolution in model evaluations and decision-making. The aim of this study is to investigate the value of different remote sensing products and groundwater level measurements in the temporal calibration of a well-known hydrologic model i.e. HBV. This has been rarely done for conceptual models as satellite data are often used in spatial calibration of the distributed models. Three different soil moisture products from ESA CCI SM v04.4, AMSR-E and SMAP, and total water storage anomalies from GRACE are collected and spatially averaged over the Moselle River Basin in Germany and France. Different combinations of objective functions and search algorithms all targeting a good fit between observed and simulated streamflow, groundwater and soil moisture are used to analyse the contribution of each individual source of information. Firstly, the most important parameters are selected using sensitivity analysis and then, these parameters are included in a subsequent model calibration. The results of our multi-objective calibration reveal substantial contribution of remote sensing products to the lumped model calibration even if their spatially distributed information is lost during the spatial aggregation. Inclusion of new observations such as groundwater levels from wells and remotely sensed soil moisture to the calibration improves the model’s physical behaviour while it keeps a reasonable water balance that is the key objective of every hydrologic model.
ARTICLE | doi:10.20944/preprints201909.0042.v1
Subject: Environmental And Earth Sciences, Remote Sensing Keywords: GRACE TWS, GRACE-FO, Nile River Basin, Spatial autocorrelation, OLS, GWR.
Online: 4 September 2019 (13:26:12 CEST)
GRACE-derived Terrestrial Water Storage Anomalies (TWSA) continue to be used in an expanding array of studies to analyze numerous processes and phenomena related to terrestrial water storage dynamics, including groundwater depletions, lake storage variations, snow, and glacial mass changes, as well as floods, droughts, among others. So far, however, few studies have investigated how the factors that affect total water storage (e.g., precipitation, runoff, soil moisture, evapotranspiration) interact and combine over space and time to produce the mass variations that GRACE detects. This paper is an attempt to fill that gap and stimulate needed research in this area. Using the Nile River Basin as case study, it explicitly analyzes nine hydroclimatic and anthropogenic processes, as well as their relationship to TWS in different climatic zones in the Nile River Basin. The analytic method employed the trends in both the dependent and independent variables applying two geographically multiple regression (GMR) approaches: (i) an unweighted or ordinary least square regression (OLS) model in which the contributions of all variables to TWS variability are deemed equal at all locations; and (ii) a geographically weighted regression (GWR) which assigns a weight to each variable at different locations based on the occurrence of trend clusters, determined by Moran’s cluster index. In both cases, model efficacy was investigated using standard goodness of fit diagnostics. The OLS showed that trends in five variables (i.e., precipitation, runoff, surface water soil moisture, and population density) significantly (p<0.0001) explain the trends in TWSA for the basin at large. However, the models R2 value is only 0.14. In contrast, the GWR produced R2 values ranging between 0.40 and 0.89, with an average of 0.86 and normally distributed standard residuals. The models retained in the GWR differ by climatic zone. The results showed that all nine variables contribute significantly to the trend in TWS in the Tropical region; population density is an important contributor to TWSA variability in all zones; ET and Population density are the only significant variables in the semiarid zone. This type of information is critical for developing robust statistical models for reconstructing time series of proxy GRACE anomalies that predate the launch of the GRACE mission and for gap-filling between GRACE and GRACE-FO.
ARTICLE | doi:10.20944/preprints201907.0164.v1
Subject: Environmental And Earth Sciences, Geography Keywords: major river; fold; geomorphology; interactions; remote sensing; characteristics; Karun; Dez; Iran
Online: 12 July 2019 (05:26:16 CEST)
There are frequently interactions between active folds and major rivers (mean annual water discharges > 70 m3s-1). The major river may incise across the fold, to produce a water gap across the fold, or a bevelling (or lateral planation) of the top of the fold. Alternatively, the major river may be defeated to produce a diversion of the river around the fold, with wind gaps forming across the fold in some cases, or ponding of the river behind the fold. Why a river incises or diverts is often unclear, though influential characteristics and processes have been identified. A new scheme for investigating fold-river interactions has been devised, involving a short description of the major river, climate, and structural geology, and 13 characteristics of river and fold geomorphology: 1) Channel width at location of fold axis, w, 2) Channel-belt width at location of fold axis, cbw, 3) Floodplain width at location of fold axis, fpw, 4) Channel sinuosity, Sc, 5) Braiding index, BI, 6) General river course direction, RCD, 7) Distance from fold core to location of river crossing, C-RC, 8) Distance from fold core to river basin margin, C-BM, 9) Width of geological structure at location of river crossing, Wgs, 10) Estimate of erosion resistance of surface sediments/rocks and deeper sediments/rocks in fold, ERs, ERd, 11) Channel water surface slope at location of fold axis, s, 12) Average channel migration rate, Rm, 13) Estimate of fold total uplift rate, TUR. The first 10 geomorphological characteristics should be readily determinable for nearly all major rivers using widely available satellite imagery and fine scale geological maps. The last 3 characteristics should be determinable for most major rivers where other data sources are available. This study demonstrates the methodology of this scheme, using the example of the major rivers Karun and Dez interacting with active folds in the foreland basin tectonic setting of lowland south-west Iran. For the rivers Karun and Dez (mean annual water discharges 575 m3s-1 and 230 m3s-1, respectively), it was found that geomorphological characteristics Nos. 2, 3 and 7 had statistically significant differences (p-value ≤ 0.05) between the categories of river incision across a fold and river diversion around a fold. For river incision, at the fold axis, channel-belt width was always < 2.7 km, and floodplain width was generally (80 % of cases) < 5.7 km; whereas for river diversion, at the projection of the fold axis, these two characteristics had a wide range of values. For river incision, the distance from the fold core to the location where the river channel crossed the fold axis, was generally (80 % of cases) ≤ 8.5 km; whereas for river diversion, this distance was always > 22 km. Since it is highly likely that different characteristics will be important for other major rivers interacting with other folds, it is recommended that this scheme is now used to investigate a variety of major rivers from across the globe. By comparing the same parameters for different major rivers, a better understanding of fold-river interactions should be achieved.
REVIEW | doi:10.20944/preprints201904.0149.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: Agro-industry; Ethiopia; oasis wheat; pasta wheat; Senegal River; value chain
Online: 12 April 2019 (11:04:08 CEST)
Durum wheat is an important food crop in the world and an endemic species of sub-Saharan Africa (SSA). In the highlands of Ethiopia and the oases of the South Sahara this crop has been cultivated for thousands of years. Today, smallholder farmers still cultivate it on marginal lands to assure production for their self-consumption. However, durum wheat is no longer just a staple crop for food security but it has become a major cash crop. In fact, the pasta and couscous industry currently purchase durum grain at prices 10 to 20% higher than bread wheat. Africa as a whole imports over € 4 billion per year of durum grain to provide the raw material for its food industry. Hence, African farmers could obtain a substantial share of this large market by turning their production to this crop. Here, the achievements of the durum breeding program of Ethiopia are revised to reveal a steep acceleration in variety release and adoption in the last decade. Furthermore, the variety release for Mauritania and Senegal is described to show how modern breeding methods could be used to deliver grain yields above 3 t ha-1 in seasons of just 92 days of length and daytime temperatures always above 32°C. This review describes the ability of releasing durum wheat varieties adapted to all growing conditions of SSA, from the oases of the Sahara to the highlands of Ethiopia. This potential area of expansion for durum wheat production in SSA is not linked to any breeding technology, but rather it remains dependent on the market ability to purchase these grains at a higher price to stimulate farmer adoption. The critical importance of connecting all actors along the semolina value chain is presented in the example of Oromia, Ethiopia, and that success story is then used to prompt a wider discussion on the potential of durum wheat as a crop for poverty reduction in Africa.
ARTICLE | doi:10.20944/preprints201806.0286.v1
Subject: Engineering, Civil Engineering Keywords: soil moisture; NARX neural networks; AMSR-E; SM2RAIN; Karkheh River Basin
Online: 19 June 2018 (09:32:11 CEST)
Accurate estimates of daily rainfall are essential for understanding and modeling the physical processes involved in the interaction between the land surface and the atmosphere. In this study, daily satellite soil moisture observations from the Advanced Microwave Scanning Radiometer - Earth Observing System (AMSR-E) generated by implementing the standard NASA- algorithm are employed for estimating rainfall, firstly, through the use of recently developed approach, SM2RAIN (Brocca et al., 2013) and, secondly, the nonlinear autoregressive network with exogenous inputs (NARX) neural modelling at five climate stations in the Karkheh river basin (KRB), located in southwest Iran. In the SM2RAIN method, the period 1 January 2003 to 31 December 2005 is used for the calibration of algorithm and the remaining 9 months from 1 January 2006 to 30 September 2006 is used for the validation of the rainfall estimates. In the NARX model, the full study period is split into a training (1 January 2003 to 31 September 2005) and a testing (1 September 2005 to 30 September 2006) stage. For the prediction of the rainfall as the desired target (output), relative soil moisture changes from AMSR-E and measured air temperature time series are chosen as exogenous (external) inputs in NARX. The quality of the estimated rainfall data is evaluated by comparing it with observed rainfall data at the five rain gauges in terms of the correlation coefficient R, the RMSE and the statistical bias. For the SM2RAIN method, R ranges between 0.44 and 0.9 for all stations, whereas for the NARX- model the values are generally slightly lower. Moreover, the values of the bias for each station indicate that although SM2RAIN is likely to underestimate large rainfall intensities, due to the known effect of soil moisture saturation, its biases are somewhat lower than those of NARX. In conclusion, the results of the present study show that with the use of AMSR-E soil moisture products in the physically based SM2RAIN- algorithm as well as in the NARX neural network, rainfall for poorly gauged regions can be fairly predicted.
ARTICLE | doi:10.20944/preprints201805.0384.v1
Subject: Engineering, Civil Engineering Keywords: fracture grouting; cement-silicate grout; geophysical prospecting; seepage; Yellow River Embankment
Online: 28 May 2018 (05:45:00 CEST)
Fracture grouting has been a widely used mitigation measure against seepage in the Yellow River Embankment. However, there is currently a lack of systematic investigation for evaluating the anti-seepage effectiveness of fracture grouting employed in this longest river embankment in China. Therefore, in this work, laboratory and in-situ experiments are carried out for investigating the reinforcement effect of fracture grouting in the Jinan Section of the Yellow River Embankment. In particular, firstly, the laboratory tests concentrate on studying the optimum strength improvement for cement-silicate grout by varying the content of backfilled fly ash and bentonite as admixtures. Flexural strength and Scanning Electron Microscope photographs are investigated for assessing the strength and compactness improvement. Subsequently, based on the obtained optimum admixtures content, in-situ grouting tests are carried out in the Jinan Section of the Yellow River Embankment to evaluate the anti-seepage effectiveness of fracture grouting, where geophysical prospecting and pit prospecting methods are employed. Laboratory results show that, compared with pure cement-silicate grouts, the gelation time of the improved slurry is longer and gelation time increases as fly ash content increases. The optimum mixing proportion of the compound cement-silicate grout is 70% cement, 25% fly ash and 5% bentonite, and the best volume ratio is 2 for the investigated cases. Geophysical prospecting using the Ground Penetrating Radar and High Density Resistivity methods can reflect the anti-seepage effectiveness of fracture grouting on site. It shows that the grouting material mainly flows along the axial direction of the embankment. The treatment that is used to generate directional fracture is proved to be effective. The injection hole interval distance is suggested to be 1.2 m, where the lapping effect of the grouting veins is relatively significant. For the investigated cases, the average thickness of the grouting veins is approximately 6.0 cm and the corresponding permeability coefficient is averagely 1.6 × 10−6 cm/s, which meets the anti-seepage criterion in practice.
ARTICLE | doi:10.20944/preprints201804.0122.v1
Subject: Social Sciences, Geography, Planning And Development Keywords: the Zuli River Basin; precipitation; runoff; sediment discharge; soil conservation measure
Online: 10 April 2018 (09:31:07 CEST)
Precipitation and human activities are two essential forcing dynamics that influence hydrological processes. To investigate those impacts, the Zuli River Basin (ZRB, a typical tributary basin of the Yellow River in China) was chosen to identify the impact of precipitation and human activities on runoff and sediment discharge. A double mass curve (DMC) analysis and the test methods, including accumulated variance analysis, sequential cluster, Lee-Heghnian, and moving t-test methods was utilized to determine the abrupt change point based on data from 1956 to 2015. Correlation formulas and multiple regression methods were used to calculate the runoff and sediment discharge reduction effects of soil conservation measures and to estimate the contribution rate of precipitation and soil conservation measures to runoff and sediment discharge. Our results show that the runoff reduction effect of soil conservation measures (45%) is greater than the sediment discharge reduction effect (32%). Soil conservation measures were the main factor controlling the 74.5% and 75.0% decrease in runoff and sediment discharge, respectively. Additionally, the contribution rate of vegetation measures was higher than that of engineering measures. This study provides scientific strategies for water resource management and soil conservation planning at catchment scale to face future hydrological variability.
ARTICLE | doi:10.20944/preprints201712.0095.v1
Subject: Environmental And Earth Sciences, Environmental Science Keywords: interception losses; water balance; water storage capacity; wetland; sedges; Biebrza river
Online: 14 December 2017 (16:36:55 CET)
This study estimates rainfall interception losses from natural wetland ecosystems based on maximum canopy storage measurements. Rainfall interception losses play an important role in water balance, which is crucial in wetlands, and has not yet been thoroughly studied in relation to this type of ecosystem. Maximum canopy storage was measured using the weight method. Based on these measurements, daily values of interception losses were estimated and then used to calculate long term interception losses based on precipitation and potential evapotranspiration data for the 1971–2015 period. Depending mainly on the number of days with precipitation, the results show that total interception losses for the growing season as well as monthly interception losses are around 13% of gross rainfall. This value is similar to the values observed for some forests. Hence, interception losses should not be disregarded in hydrologic models of wetlands, especially because data trends in meteorological conditions (mainly number of days with precipitation) show that interception losses will increase in the future if those trends stay the same.
ARTICLE | doi:10.20944/preprints201711.0185.v1
Subject: Social Sciences, Behavior Sciences Keywords: Atoyac River; water pollution; heavy metals; coliforms; Emilio Portes Gil; Puebla
Online: 29 November 2017 (07:43:21 CET)
The Atoyac River crosses the metropolitan area of Puebla, Mexico, and presents a condition of severe degradation that has been poorly studied. The research was conducted in the year 2016 and analyzed the space-time dynamics of the water quality of the river, the increase in pollution in the period 2011–2016, and the water quality of the Atoyac River used for agricultural irrigation and human consumption in the population of Emilio Portes Gil, Ocoyucan, based on official Mexican standards (NOMs). The anoxic state of the river was demonstrated (~1.47 mgO2/L) and the high organic pollution, particularly in drought, as well as the presence of large populations of coliform bacteria, and 11 enterobacteries of pathogenic importance. The pollution recorded an average increase of 49% in the period 2011-2016, and the values of Fe, Al, Pb, and Cd in variable percentages. It was evidenced that water for irrigation and wells is contaminated with fecal bacteria (104–549 NMP/100 mL), including pathogenic. In wells, the concentration of heavy metals was 5 times higher in drought. These results represent a serious threat for the population of Emilio Portes Gil and the environment in the metropolitan area of Puebla.
ARTICLE | doi:10.20944/preprints201608.0193.v1
Subject: Environmental And Earth Sciences, Environmental Science Keywords: chromophoric dissolved organic matter; polluted waters; optical properties; Yinma River watershed
Online: 23 August 2016 (10:35:36 CEST)
Spectral characteristics of CDOM in water column are a key parameter for bio-optical modeling. Knowledge of CDOM optical properties and spatial discrepancy based on the relationship between water quality and spectral parameters in Yinma River watershed with in situ data collected highly-polluted waters are exhibited in this study. Seasonal field data sets collected over a period of 2 months in 2015 in Yinma River Watershed. Based on the comprehensive index method, the riverine waters showed serious contamination, especially the COD, Fe, Mn, Hg and DO were out of range contamination warning. Dissolved organic carbon (DOC) and total suspended matter (TSM) with prominent non-homogenizing were significantly high in the riverine waters, but chlorophyll-a (Chl-a) was opposite. Ternary phase diagram showed that non-algal paritcles absorption played an important role in total non-water light absorption (>50%) in most sampling locations, and mean contribution of CDOM were 13% and 22% in summer and autumn respectively. Analysis of ratio of absorption at 250-365 nm (E250:365) and spectral slope (S275-295) indicated that CDOM had higher aromaticity and molecular weight in autumn than in summer, is consistent with the results of water quality and relative contribution. Redundancy analysis (RDA) indicated that the environmental variables OSM had a strong correlation with CDOM absorption, followed by heavy metal, e.g., Mn, Hg and Cr6+. However, for the specific UV absorbance (SUVA254), the seasonal values showed opposite results compared with the reported literature. The potential reasons were the more UDOM (uncolored Dissolved Organic Matter) from human source (wastewater effluent) existed in waters. Terrigenous inputs simultaneously are in relation to the aCDOM(440)-DOC relationship with the correlation coefficient was 0.90 in summer (2-tailed, p<0.01), and 0.58 in autumn (2-tailed, p<0.05). Spatial distribution of CDOM parameters exhibited that the downstream regions focused on dry land have high CDOM molecular weight and aromatic hydrocarbon. Partial sampling locations around the cities or countries generally showed abnormal values due to terrigenous inputs. As a bio-optical model parameter, spectral characteristic of CDOM is helpful in adjusting the derived algorithms in highly-polluted environments. The study on organic carbon and pollutants in highly-polluted waters had an important contribution to global carbon balance estimation and water environment protection.
ARTICLE | doi:10.20944/preprints201806.0164.v1
Subject: Engineering, Civil Engineering Keywords: Integrated water resources management; support to decision-making process, streamflow forecast; simple and low-cost forecasting model; Guadalquivir River Basin; Genil River; Canales reservoir; Quéntar reservoir
Online: 11 June 2018 (16:40:22 CEST)
Forecasting streamflow accurately is essential to achieve an efficient integrated water resources management strategy and provide consistent support to water decision-makers. We present a simple, low-cost and robust approach for forecasting monthly and yearly streamflow during the hydrological year in course, applicable to headwater catchments. It combines the use of regression analysis techniques, the two-parameter Gamma continuous cumulative probability distribution function and the Monte Carlo method. It is based on a probabilistic comparison of the progression of the current hydrological year with the historic observed series. The methodology has been successfully applied to two headwater reservoirs within the Guadalquivir River Basin in southern Spain. The root-mean-square error and correlation coefficient were used to measure the accuracy of the model and the results showed good levels of reliability. The outputs are the probabilistic monthly and yearly streamflow and 80% confidence interval. Further reductions in prediction errors may be achieved from increasing the number of observed years. These risk-based predictions are of great value, especially, before the intensive irrigation campaign starts (usually in April), when Water Authorities are to take responsible management decisions about the best allocation of the available water volume between the different water users and environmental needs.
COMMUNICATION | doi:10.20944/preprints202311.1991.v1
Subject: Biology And Life Sciences, Aquatic Science Keywords: chum salmon; fertilized eggs; salinity tolerance; hatching rate; spawning ground; Namdae River
Online: 30 November 2023 (14:17:49 CET)
Chum salmon (Oncorhynchus keta) exhibit a remarkable ability to adapt to changes in salinity during their life cycle. However, the fertilized egg stages are sensitive to salinity, affecting on-togeny and hatching. This study investigated the effect of salinity (0, 1, 3, and 5 psu) on the sur-vival of two developmental stages (< 1 day after fertilization and < 1 day after the eyed-egg stage) of fertilized eggs. Based on the experimental results, we assessed the spawning ground environ-ment of the Namdae River, where the largest number of salmon in Korea migrate to spawn. Sur-vival of the < 1 day old fertilized eggs decreased sharply at 3 psu or more, and all eggs died at 5 psu. Hatching rates of the eyed-egg stage varied depending on salinity, but hatching occurred under all environmental conditions. After 2010, the salinity of the layer of water in contact with the sediment in the lower reaches of the river tended to increase (> 6.9 psu) with the frequency of high waves. Overall, the function of the lower river in spawning and hatching is weakening. This study enhances our understanding of the effects of climate change, including increased wave ac-tivity, on salmon spawning grounds
ARTICLE | doi:10.20944/preprints202311.1467.v1
Subject: Environmental And Earth Sciences, Pollution Keywords: microplastics, polyethylene, polystyrene, polypropylene, characterization, identification, FT-IR, Raman, Somesul Mic River
Online: 23 November 2023 (04:54:42 CET)
Microplastics (MPs) pollution has become a persisting problem over the last decades and a critical issue for environmental protection and human health. In this context any scientific data able to reveal the MPs presence and to improve the characterization and identification in different systems is valuable. The aim of this paper was to assess available techniques for determining MPs in real freshwater samples and subsequently to highlight the occurrence and type of MPs in the study case area (Somesul Mic River). The specific objectives of the study were: i) MPs separation and visual characterization; ii) microscopic analyses and morphological characterization of MPs; iii) Raman and FT-IR spectroscopic identification of MPs. MPs sampling was performed from the fresh water and sediment using planktonic nets and sieves with different mesh sizes (20 to 500µm). After digestion with hydrogen peroxide, the MPs characterization was performed using both classical microscopic techniques as well as scanning electron microscopy (SEM). For the MPs identification, Raman and FT-IR spectrometry techniques were used. Large (1-5 mm) and small (1 µm to 1 mm) MPs were observed in the shape of fibers, fragments, foam, foils and spheres in various colors (red, green, blue, purple, pink, white, black, transparent, opaque). Polymers were identified related to scientific literature and reference spectra. The presence of polyethylene (PE), polypropylene (PP) and polystyrene (PS) was registered for all sampling point. The MPs laboratory investigations have raised some issues regarding the identification of MPs particles with the size smaller than 500µm, being characterized especially under microscope. Small MPs particle dispersed on cellulose filter were identified using micro-Raman spectroscopy highlighting the same type of polymers. The results showed that both spectrometric methods Raman or FT-IR confirm the identification of the same type of polymers. No differences were registered between the sampling points due to the widespread presence of MPs. The sediments samples presented a greater abundance compared to the water samples. Overall, it is necessary to continue the optimization of the MPs separation protocol and identification according to the complexity of samples, mainly due to the limitation and lack of spectral databases.
ARTICLE | doi:10.20944/preprints202311.0889.v1
Subject: Environmental And Earth Sciences, Geography Keywords: anastomosing river; hydrodynamic parameters; calculation method; shape factor; scale factor; gradient factor
Online: 14 November 2023 (10:35:46 CET)
Anastomosing rivers are wetland systems with multiple channels, and there are many constraints limiting in-situ observations of their hydrodynamics. Therefore, there are few reports on the hydrodynamic data of such rivers. In order to obtain the hydrodynamic parameters of the river channels without hydrological observations in the anastomosing rivers, this study proposes an expression method namely expression of channel morphological parameters (ECMP) for hydrodynamic calculations. The calculation formula of the ECMP method based on the shape factor, scale factor, and gradient factor of the flow cross-section as independent variables. This method can be used to calculate the average velocity, discharge, specific stream power, gross stream power and other hydrodynamic parameters of the flow cross-section at different water levels, only requiring the measurement of morphological parameters such as the average depth, width-depth ratio, and gradient of the flow (channel) cross-section. The applicability of the ECMP method was verified using measured hydrological data. The results show that the ECMP method is a practical calculation method with high computational accuracy and convenient application for calculating river hydrodynamic parameters. It has great application value in study on fluvial geomorphology and hydrodynamics, as well as in the reconstruction of ancient river hydrology and hydrodynamics.
ARTICLE | doi:10.20944/preprints202310.1751.v1
Subject: Physical Sciences, Other Keywords: Lightning; Land Cover and Land Use; Topographic Effects, Itacaiúnas River Hydrographic Basin
Online: 30 October 2023 (06:52:52 CET)
Keywords: Lightning; Land Cover and Land Use; Topographic Effects, Itacaiúnas River Hydrographic Basin
ARTICLE | doi:10.20944/preprints202309.2161.v1
Subject: Computer Science And Mathematics, Artificial Intelligence And Machine Learning Keywords: pollution; dissolved oxygen; Credit River; machine learning; graph neural networks; SHAP analysis
Online: 30 September 2023 (08:15:54 CEST)
An important indicator of human-related pollution in watersheds is dissolved oxygen (DO). The DO is highly dependent on both space and time characteristics of the watershed and is directly linked to eutrophication, which impairs the development of both the aquatic fauna and flora, also negatively impacting the water quality. Aspiring to reach a more accurate and precise forecasting approach to predict levels of DO, the present work proposes new graph-based and transformer-based deep learning models. The models were trained and validated for the Credit River Watershed, and the results were compared with both benchmarking and literature-found approaches. The proposed Graph Neural Network Sample and Aggregate (GNN-SAGE) model was the best-performing approach, reaching coefficient of determination (R2) and Root Mean Squared Error (RMSE) values of 97% and 0.34 ppm, respectively. The findings from the Shapley additive explanations (SHAP) indicated that the GNN-SAGE benefited from spatiotemporal information from the surrounding stations, improving the model’s results, and that temperature is a major input attribute for determining future DO levels. The results established that the proposed GNN-SAGE model stands as a state-of-the-art solution for DO forecasting, with potential for real-time water quality applications.
ARTICLE | doi:10.20944/preprints202309.1991.v1
Subject: Environmental And Earth Sciences, Ecology Keywords: fish; river connectivity; land use; physiochemical variable; spatial gradient; Lake Chaohu Basin
Online: 28 September 2023 (10:40:21 CEST)
Human disturbances can have severe environmental impacts on freshwater ecosystems. The main aim of this study was to detect the influences of physiochemical variables, land-cover characteristics, and river connectivity on fish assemblages in Lake Chaohu Basin, China. A cluster analysis of the river connectivity variables identified four groups of sites that characterized by significantly different connectivity gradients in local scale. These four groups of sites showed increasing connectivity from the upper reaches to the lower reaches. At the same time, among the four groups, the values of the environmental variables generally increased from the upper reaches with less human activity towards the lower reaches with more human activities. For instance, some main physiochemical variables (e.g., river width, water depth, nitrate, phosphate) significantly increased among the four groups. In contrast, fish taxa richness and diversity indices were not significantly different among the four connectivity groups. However, fish assemblages showed significant variation among the connectivity groups (p=0.026). In addition, the study determined that upper riparian land uses (e.g., woodland and grassland), flow velocity, and elevation were environmental variables regulating the variance in the fish communities, and for the connectivity variables, only river order and number of branches along a path to the left of the main stem affected the variance in the fish communities. Therefore, new practices aimed at maintaining and even increasing the riparian canopy coverage and the flow velocity of rivers should be integrated into local conservation planning for freshwater ecosystems, especially in the upper reaches of the basin.