高关灌区现代化改造对大富水斑鳜保护区水文及栖息地的影响OA

To identify the impact of increased irrigation water withdrawal from Gaoguan Reservoir on the downstream National Aquatic Genetic Resources Reserve of Siniperca Chuatsi in Dadushui River after the supplementary construction and modernization renovation of Gaoguan Reservoir,the temporal and spatial variations of runoff,water level and water temperature downstream of the dam were predicted in this study based on DEM data and MIKE11 model,focusing on analysis of the ecological base flow protection and suitable habitat conditions for the Siniperca chuatsi.The results showed that after the operation of the project,the sectional runoff at the dam site decreased most significantly in the normal flow year(44.24％),but all river sections met the requirement of ecological base flow of 0.3 m3/s,and the section at the upper boundary of the reserve could reach the minimum ecological water demand standard of 2.34 m3/s.The variation range of water level downstream of the dam was 0.08％-0.95％,with limited impact on physical habitats.Under the scenarios of designed flood level and normal flow level,slight water temperature deviations were only observed at Tiandian Pump Station section in April,May and September,while the water temperature could be fully restored to the natural level in the dry season.All scenarios met the spawning temperature requirements for the Siniperca chuatsi.The study concludes that the overall ecological impact of the project is controllable.Adopting priority scheduling of shallow/surface-layer water withdrawal can further ensure the ecological security of the reserve,offering a scientific foundation for upgrading the irrigation system and coordinated development of basin-scale ecological conservation.