Simulation And Layout Optimization Of Low Impact Development Of Sponge City In Dry Area

The simulation and layout optimization of low-impact development of sponge cities in arid area can effectively control urban waterlogging,reveal the hydrological response law of sponge cities in arid area,and find the optimal construction model of sponge cities that adapts to the characteristics of arid area,so as to provide decision reference for sponge city construction.This study selected the central part of Jinfeng District in Yinchuan as the research area.The study based on some data sources,for example,DEM(5m),land use types,drainage network and rainfall data of study area.First,the node overflow and drainage capacity of pipe network in study area are simulated and evaluated by using Storm Water Management and Geographic Information System.A zoning map of urban waterlogging risk is made according to the depth and duration of water accumulation in each node of pipe network simulated by the SWMM and land-use grade assessment.Second,responses of spatial allocations for single permeable pavement,single rain garden,single green roof and their combinations to total runoff,peak runoff and runoff coefficient are simulated by using the SWMM and GIS under different recurrence periods to alleviate the urban waterlogging.Flood control effects of seven Low Impact Development layout schemes are evaluated.Finally,spatial allocation of LID facilities is optimized by using a site selection tool of Best Management Practices in the GIS environment to obtain the optimal LID scheme for flood control.The results are shown that:(1)Sub-catchments with high land-use grade,water-accumulation depth of more than 40 cm,and water-accumulation time of more than 1 h are prone to become high risk areas of waterlogging.(2)Spatial allocation schemes of LID practices have significant influences on flood control.The pairwise combinations of permeable pavement&green roof,green roof&rain garden,and rain garden&green roof have better flood control performances than single LID schemes.The combined scheme of permeable pavement&green roof&rain garden has the largest reduction rates of peak runoff,total runoff,and runoff coefficient.(3)Optimal spatial allocation of LID practices can obtain 80%reduction rates of total runoff,peak runoff,and runoff coefficient,and has great economic benefits.which indicates better flood control and higher economic benefits of the optimal LID layout than that of the traditional urban development.