Application of GT-GRA-TOPSIS in Location Selection and Quantity Optimization of Rainwater Storage Tank

Purposes In order to effectively alleviate the urban flood caused by extreme rainstorm weather, the site selection and quantity optimization of rainwater storage tanks (SST) in urban rainwater drainage system were investigated. Methods Game theory (GT) was used to combine the subjective weights obtained by the analytic hierarchy process with the objective weights obtained by the improved entropy value method. Furthermore, the grey relevance analysis (GRA) and technique for order preference by similarity to ideal solution (TOPSIS) were combined to establish a quantitative assessment framework for urban waterlogging and non-point source pollution risks. The risk level was determined according to the relative proximity of each node, and SST was set for the node with higher risks. The number of SST was then optimized according to the reduction rates of stagnant water and total suspended solids. With Changzhi City, Shanxi province as an example, the control effect of this method on urban waterlogging and non-point source pollution under different rainfall return periods was discussed. Findings The results show that at 5 a and 10 a rainfall return periods, the comprehensive coefficients of variation of GRA-TOPSIS method are 0.355 and 0.361, respectively, and the extreme values are both 0.496, higher than that of GRA or TOPSIS alone. Conclusions Optimization method of GT weighting and coupling GRA-TOPSIS can better eliminate the risk of urban waterlogging and non-point source pollution with less economic investment, and provide a new thought for SST location and quantity optimization.