Assessment of impacts of water transfer on lake flow and water quality in Lake Chaohu using a three-dimensional hydrodynamic-ecological model

Abstract

Study region: Lake Chaohu is a typically large shallow freshwater lake in China, experiencing long-term eutrophication and a short period of drought. Study focus: This study employs a three-dimensional (3-D) hydrodynamic-ecological model to assess the impacts of water transfer on lake flow, water quality, and their relationship, and then reveals optimal strategies for achieving improved water quality in Lake Chaohu. New hydrological insights for the region: Results indicated that clean water transfer could dramatically increase flow rate and decrease nutrient concentrations near the water transfer inlets, while the grade level of lake water quality is not changed. The degree of improvement in water quality parameters is not always proportional to lake flow rate. A clean water transfer through the eastern route (ZH) has the largest improvement effect on the average flow rate and water quality (total nitrogen (TN) and total phosphorus (TP)) of the entire lake. Winter water transfer improves TN and TP better than summer, while the opposite for ammonia nitrogen (NH3-N). Decrease of wind speed is essential for mitigating nutrient accumulation in western lake’s heavily polluted bay through weakening the reverse circulation and the northwest flow. Water transfer operations are revealed to improve water quality in Lake Chaohu: conduct water transfer through ZH in winter, strictly control NH3-N concentration in the donating water, and combine the effects of the low east wind.

Keywords

• Water transfer
• Lake water flow
• Nutrients
• Wind field
• Lake management