Land-use planning plays an important role in agricultural development, however it lacks tools to support planner in proposing land-use planning solutions especially, under saltwater intrusion condition in the coastal regions. This study aims to apply optimization in analyzing land-use solutions for agricultural land-use planning. In which a multi-objective optimization model is developed to optimize land-use area including land-use allocation taking into account socio-economic and environmental factors. The model has been applied in three districts of Soc Trang province, Vietnam (Long Phu, My Xuyen and Tran De) representing three ecological regions including salt water, brackish water and freshwater in the Mekong Delta of Vietnam. The results showed that two multi-objective optimization scenarios (in terms of profit, labor, environment benefits and risk reduction) have been implemented: (i) Multi-objective optimization of agricultural land-use until 2030 under normal conditions; (ii) Optimizing agricultural land-use until 2030 under climate change conditions similar to the 2016 drought and saltwater intrusion phenomenon in the Mekong Delta. The results showed that the second scenario is the option considered for implementing land-use plan thanks to the balance between good profits and minimizing economic and environmental risk. The land allocation was carried out taking into account household economic, the influence of adjacent production types, local traffic and canal systems factors to allocate optimal land-use areas. The combination of land-use optimization and spatial allocation process can help planners improve the quality of agricultural land-use planning.

Researchers have reported various impacts of the COVID-19 outbreak on small-scale fishers, such as stagnating market demands, reduction of market price and income, etc. While literature have heeded to these impacts in a relatively short time frame, scant evidence exists on the changing impacts over time and on the detailed processes of how fishers have been coping with the challenges in a longer time period. Furthermore, few studies have comprehensively analysed the impacts and strategies from multiple perspectives. This study aims to explore the perceived impacts of the COVID-19 outbreak on small-scale fishing communities and to highlight the coping strategies adopted by fishers over a year since the initial outbreak, through a case study in Trang Province, Thailand. Analysis of both qualitative and quantitative data obtained through semi-structured interviews indicated that fishers wisely utilised natural, financial and social capitals at the early stages of the outbreak, while human capitals were essential for recovering from the impacts in the later stages. Our findings suggest that the adaptive capacity to flexibly change livelihood strategies are crucial, while alternative income source may not necessarily help small-scale fishers under stagnating global economy.

Ca Mau Peninsula (CMP), the southernmost region of the Mekong Delta, is facing a severe loss of land and freshwater. Particularly, the groundwater resources in the complex multilayered aquifer system of CMP are subject to salinization processes, which are not yet fully understood. In this study, an existing groundwater flow model for the CMP was enhanced to a density-dependent transient transport model using the FEFLOW software package, which is based on the finite element method. The study focuses on simulating groundwater salinity in order to better understand the dynamics of groundwater salinization and potential saltwater intrusion pathways in the study area. Time series of Total Dissolved Solids (TDS) concentrations at observation wells were used to compare simulated and observed salinity data in different aquifers. The model allows a multi-factorial evaluation of the spatial groundwater salinity and could also confirm significant inter-annual variability, particularly in the case of shallow aquifers due to the influence of tides and seasonal rainy/dry seasons. Using sensitivity analysis, leakage from upper saline aquifers into lower freshwater aquifers through natural hydrogeological windows and poorly sealed boreholes was identified as a potential major cause for groundwater salinization occurring in the region. The results obtained can serve as an important basis for developing decision-making tools to promote the sustainable use of water resources on the CMP in the future.