Effects of ecological flow release patterns on water quality and ecological restoration of a large shallow lake

Large shallow lakes play an important role in providing water for domestic supply and landscape irrigation, and maintaining a healthy ecosystem. A lake ecosystem possesses abundant aquatic plants and animals. Changes of the hydrological regime affect the water level, water quality, and species distribution. In this study, a two-dimensional hydrodynamic and water quality model is applied to a large shallow lake, Baiyangdian Lake. The model was established based on measured lake bed elevation, hydrological data, and water quality data. This model was validated for two water transfer events and wind-driven circulation in local areas was observed in the model results. Influences of water transfer and wind effects on water flow and distribution of ammonium and phosphate were then evaluated and discussed. A total of eighteen water transfer scenarios were simulated. The entire lake flow field and water transfer routes in the lake and nutrient distributions were analyzed under each water transfer scenario. The water transfer suggestions proposed in this paper are based on hydraulic characteristics of the lake and make up for deficiencies that previous did not consider the effects of flow transfers on the flow field of receiving. The environmental flow patterns and ecological restoration measures for Baiyangdian Lake are proposed based on the lake hydrodynamics and flow routes under different water transfer scenarios.