Simulation on Water Supplement Process Based on Replacement Efficiency of Artificial Lake

To maintain the water quality of artificial lakes, environmental restoration or water replacement practices are common measures to be taken. Unfortunately, due to the lack of understanding on hydraulic characteristics and water replacement, the replacement efficiency is always not satisfied. In this paper, we toke the Jinsha Lake, an artificial lake in China, as an example to simulate the water flow characteristics and the optimal outlet schemes to facilitate its replacement efficiency. A depth-averaged two-dimensional mathematical model was established. Two outlet schemes, South Outlet (SO) and South East Outlet (SEO), were simulated. The study explored replacement efficiency of the lake by using tracer. The uniformity of artificial lake velocity, the area of stagnant water (velocity＜0.001 m/s) and the replacement efficiency within the same period (30 days) were analyzed. The velocity distribution of the two schemes are similar. The stagnant area of the SEO scheme is 7.5% of the whole area, 2.9% higher than that of the SO scheme. The water displacement efficiency of the SO scheme is 84%, which is 3.6% higher than that of the SEO scheme. The best outlet location scheme is obtained to be the SO scheme. In addition, other measures to improve the replacement efficiency of artificial lakes is put forward, such as increasing inflow rate, adding diversion outlets, changing the topography, introducing water purify organisms and so on. The research is expected to provide vital information for water quality improvement and ecological diversity of the artificial lakes.

Keywords: artificial lakes; replacement efficiency; hydraulic conditions