Construction and application of urban water system connectivity evaluation index system based on PSR-AHP-Fuzzy evaluation method coupling

The connectivity of urban water systems can enhance the connectivity of regional rivers, lakes, and water systems, which can improve the regional water environment and water ecology to a certain extent, and enhance the water disaster prevention capability. To scientifically evaluate the effect of water system connectivity in the comprehensive urban water system management project. In this study, a regional waterlogging model based on the coupling of ArcGis and SWMM is established. At the same time, the evaluation index system of water system connectivity effect of regional town water system comprehensive management project was constructed regarding PSR ("Pressure-Status-Response") theory with structural connectivity, hydraulic connectivity and ecological and environmental improvement as the criteria, and the fuzzy evaluation method was used for analysis and evaluation. The results show that the improvement in the water environment is obvious after the water system is connected. The total length and area of rivers in the study area increased by 68.98% and 57.51%, respectively. River network density increased from 0.66 km/km2 to 0.69 km/km2, an increase of 4.55%; the regional water surface rate increased from 2.22% to 3.51%, an increase of 58.11%; the river frequency increased from 0.15/km2 to 0.29/km2, an increase of 93.33%. The water exchange capacity increased by 37.5% and the flow rate increased by 30%. All water systems have a better degree of connectivity and a better structure of river network water system. The decay rate of point source pollution increased by 40.61%, the water quality of rivers reached V standard, and the area covered by green areas increased to 32.29%. The evaluation grade of hydraulic characteristics and ecological environment indexes was "excellent". The total evaluation set D=[0.5417,0.0791,0.2125,0] for the effect of water system connection in the study area. According to the principle of maximum affiliation, the improvement effect of the water system connection project in the study area is "excellent".