The eutrophication caused by excessive total nitrogen(TN) and total phosphorus(TP) emissions has been widely concerned by the whole society. Studies have revealed the relationship between land use and TN and TP, but the relationship between land use compound topographic position and TP and TN was seldom studied. Therefore, Spearman correlation and redundancy analyses were used to reveal the relationship between land use compound topographic position and TN and TP based on the monthly data of 28 water quality sampling sites and the land use data of 2013 and 2016 in the lakes of Guizhou Plateau. The results show that the nutritional state of the HBA watershed is medium. The trophic level index (TLI) value and TN concentration were high during flood, while TP concentration was high in dry period. The TN concentration in the tributaries was higher than that in the reservoir area. Construction and valley were the sources of the pollution, whereas forest land and gentle slope were the sink. According to the”source-sink”effect, the optimal zoning of land use was completed, and the urban land pollution govern area should be strengthened firstly. This paper can provide decision support for water environment management and sustainable development decision-making.

The cavitation behavior of cryogenic liquids in the field of cryogenic engineering is distinct, showcasing fundamental differences from the cavitation behavior observed in ambient temperature water. Cavitation occurrence imposes severe limitations on the operational stability of cryogenic media transportation equipment, leading to safety concerns and increased manufacturing costs. Investigating the spatiotemporal characteristics of cavitation in cryogenic fluids holds significant value for both academia and engineering. The complexity of cavitation in cryogenic fluids primarily manifests through the coupled effects of thermodynamics, vortices, and bubbles during the cavitation process. In order to further explore the coupling mechanism, numerical simulations employing the Delayed Detached Eddy Simulation (DDES) turbulence model and Sauer-Schnerr cavitation model are conducted to validate the accuracy of the numerical calculations using the Hord experiment hydrofoil as a benchmark. Subsequently, the unsteady cavitation flow of liquid nitrogen around the NACA 0015 hydrofoil is simulated by the same numerical calculation method. The results indicate that the simulated results best coincide with experimental results when the bubble number density in the Sauer-Schnerr cavitation model reaches 108. The upstream development of the re-entrant jet under the driving force of inverse pressure gradient is the fundamental reason for the detachment of the primary cavitation zone. Under the same inflow cavitation number, the thermodynamic effect significantly inhibits the generation of bubbles and changes the range of the inverse pressure gradient, thus affecting the separation behavior of the primary cavitation zone.