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

To maintain the water quality of the artificial lakes, environmental restoration or water replacement practices are favorite measures to take. Unfortunately, due to the lack of research on hydraulics characteristics and water replacement methods, the replacement efficiency is always not satisfied at present. In this paper, we take the Jinsha Lake, an artificial lake in China, as an example to simulate the water flow characteristics and its replacement efficiency. A depth-averaged two-dimensional turbulent mathematical model is established. The calculation area is provided with one water intake and one outlet. Two outl

et schemes, south outlet and southeast outlet, were simulated with steady flow. The uniformity of artificial lake velocity, the area of stagnant water (velocity＜0.001 m/s） and the replacement efficiency within the same time span of the lake are analyzed and compared. In these two schemes, the distribution of mean velocity is completely different. With respect to the southeast outlet scheme,, the stagnant area (velocity＜0.001 m/s) is 7.5% of the whole area, 2.9% higher than that of the south outlet scheme. With respect to the south outlet scheme, the water displacement efficiency is 84%, which is 3.6% higher than that of the scheme with the outlet located in the southeast during a calculation period (30 days). Comparing the three water cycle characteristics above, the best outlet location scheme, which is in the south of the intake, is obtained. In addition, other measures to improve the replacement efficiency of artificial lakes is put forward, such as increasing inflow volume, adding diversion outlet, changing the topography of stagnant water area, and using water purify organisms and so on. Simulation results show that the characteristic of the water cycle in artificial lakes is the key factor to affect the water quality. Research can provide vital information for water quality improvement and ecological diversity of the artificial lakes. Additionally, this study can establish a research foundation for the scientific construction of the artificial lakes.

Keywords: artificial lakes; replacement efficiency; hydraulic conditions