Simulation of water temperature and analysis of stratified water intake effect of stoplog gates at Xiluodu Reservoir

Abstract

[Objective] After the reservoir operation of the downstream cascade reservoirs of the Jinsha River, the water temperature structure of the reservoir area and the water temperature variation in the downstream river channel were significantly impacted. The study of the spatiotemporal distribution characteristics of water temperature in the reservoir area and the effects of stratified water intake with stoplog gates is crucial for the protection of the river's ecological environment. [Methods] Taking Xiluodu Reservoir as an example, the Delft3D model was employed to simulate the three-dimensional water temperature distribution in the reservoir area, and the effect of stratified water intake by stoplog gates on downstream discharged water temperature increase was predicted. [Results] The result indicated that the water temperature at Xiluodu Reservoir exhibited seasonal stratification, with significant stratification in spring and summer, and almost no stratification in autumn and winter. Installing stoplog gates in front of the power station intake could increase the temperature of the downstream discharged water, but the improvement was limited. Single-layer stoplog gates could increase the temperature by 0.10 to 0.30 ℃, and double-layer stoplog gates could increase it by 0.10 to 0.40 ℃. However, the improvement gradually weakened over time. The arrangement of stoplog gates also had an impact on the downstream water temperature. Installing stoplog gates at only some of the water intakes did not significantly enhance the overall temperature of the downstream discharged water. [Conclusion] The water temperature structure of Xiluodu Reservoir is stratified. When the water temperature stratification is pronounced, the overall downstream discharged water temperature can be improved by placing stoplog gates on both the left and right banks. Simulating and predicting the water temperature stratification pattern of the reservoir and effectively assessing the influence of stratified water intake with stoplog gates can provide a reference for optimizing the implementation plan for ecological scheduling at Xiluodu Reservoir.

Keywords

river-type reservoir / ecological scheduling / water temperature simulation / numerical simulation / stoplog gate / Delft3D