Optimizing turbine withdrawal from a tropical reservoir for improved water quality in downstream wetlands

摘要: Large reservoirs in the tropics act as efficient nutrient traps and often develop hypoxic conditions hypolimnion. Both effects may have severe implications for aquatic ecosystems, such limited primary production downstream riparian agriculture natural wetlands due to reduced loads, and, if hypolimnetic waters are withdrawn, that pose toxic risks rivers. This study using Itezhi-Tezhi Reservoir (Zambia) a model system aims at defining optimized turbine withdrawal prevent hypoxia relieve low-nutrient Kafue Flats floodplain. A biogeochemical 1-D simulating reservoir-internal processes water quality outflow was used estimating dissolved oxygen (DO) concentrations inorganic nitrogen phosphorus loads outflow. The depth of withdrawals varied set simulations optimize quality. Releasing shown result lower average DO 4.1-6.8 mg l(-1) compared current 7.6 l(-1). More importantly, will remain during up 189 days. Meanwhile, withdrawing nutrient-rich compensated effectively losses reservoir sediment. output could be scenario with 50% epilimnetic discharge originating from approximate 13 m depth. In this optimal scenario, prevented permanently, decreased moderately 5.2 Additionally, five-times higher N P resulted comparison dam operation.