Abstract: In recent years, aquatic plant disasters in cascade reservoirs with low head due to slow flow velocity and small water depth has emerged as a new problem in reservoir management. To tackle the Elodea canadensis disaster in the Wangfuzhou Reservoir area, an approach involving local topographic transformation was implemented. The aim was to create an unfavorable hydrological environment for the growth of Elodea. We propose a concept of hydrodynamic improvement rate to quantitatively describe the changes in hydrodynamic strength before and after transformation. Furthermore, we established an entropy-TOPSIS model to select the optimum plan for each area in comprehensive consideration of the hydrodynamic improvement effect, the environmental impact, and transformation benefits. The major findings are as follows: in area A, under periodic flow rate, modification scheme 1 exhibits a meager hydrodynamic improvement rate of only 5.16%, which is much lower than the rates achieved by scheme 2 (59.15%) and scheme 3 (63.62%). For area B and area C, scheme 1 weakens the hydrodynamic strength, while scheme 2 and scheme 3 yield improvement rates of 16.02% and 20.19% for area B, and 45.47% and 51.99% for area C, respectively. The improvement rates of both scheme 2 and scheme 3 are relatively close. By using the entropy weight method, we obtained the weights of each index in the three areas, ranking from transformation benefit to average transformation depth and hydrodynamic improvement rate in descending order. Taking into account the overall hydrodynamic improvement rate, environmental impact, and transformation benefit, the comprehensive evaluation index calculated using the TOPSIS model suggests that Scheme 3 is superior to Scheme 2 and Scheme 1. Thus, Scheme 3 is identified as the optimal transformation scheme for each area.

Key words: habitat renovation of reservoir beach, hydrodynamic improvement rate, entropy weight, TOPSIS model, Elodea canadensis, Wangfuzhou Reservoir