Evaluation Of Urban Water System Connectivity Based On SWMM

Great changes have taken place in the structure and connectivity of river water system due to the rapid development of urbanization.The water environment is gradually deteriorating,the water ecological function is gradually declining and the river cannot meet the standard flood control and drainage requirements.The occurrence of these phenomena has affected people’s living environment and the sustainable development of society.In order to solve the problem of urban water environment and achieve harmony between people and water,it is urgent and imperative to carry out comprehensive treatment of urban water environment and"river-lake system connectivity".There is no denying the importance and value of scientific assessment of the implementation effect of urban water environment treatment projects.However,how to scientifically assess the implementation effect of these projects and analyze the impact of project construction on the water environment is a difficult problem.This study consists of two main parts.In the first part,the paper constructs an index system for assessing the effectiveness of urban water system connectivity with respect to the characteristics of urban water system and projects in China.The index system assesses contains four aspects:quantitative,structural,spatial and hydraulic characteristics.In the second part,this paper establishes a hydraulic and water environment simulation model based on Chicago rainfall type,the regional measured precipitation data and regional storm formula using Arc GIS and SWMM.Then this paper presents a comprehensive assessment of the effect of water system connectivity in urban areas after the implementation of the water environment treatment and ecological restoration project in Pingyu County in terms of changes in quantitative,structural,spatial and hydraulic characteristics and water environment.The results showed that the water system in urban areas has changed significantly after the implementation of the water environment treatment and ecological restoration project.The total length of urban rivers increased by 50.01%,and the total water area increased by138.55%.The river network density increased from 0.43 km/km~2 to 0.63 km/km~2,an increase of 46.5%.The proportion of regional water surface increased from 0.95%to 2.26%,an increase of 137.89%.The river frequency increased from 0.19/km~2 to 0.28/km~2,with an increase of52.63%.Flow exchange capacity increased by 98.81%,flow velocity increased by 7.10%,and water environment improvement capacity increased by 45.47%.