Discussion Of Chongqing's Residential Districts Rain Garden Design Based On The Concept Of Low-impact Development

With the accelerating of urbanization process, urban architecture and hard pavement have emerged. All kinds of environmental problems, especially problems of urban rainwater, have become increasingly prominent. Currently, as an effective way to restore urban ecological balance, it is recognized that sponge cities and rain gardens can relieve urban rainwater and environment. Chongqing is the only typical mountain city among pilot cities of sponge city, where urban rainwater runoff fast, erode strongly and the frequent rainwater disasters could easily lead to the loss of land. The residential area in Chongqing is a representative of mountainous residential area, which is an important part of urban green space, and thus the construction of rain gardens has become a pressing issue. By reading literature, consulting data and field research, this paper presents design strategies and methods of introducing rain garden into residential areas in Chongqing.Based on reading a lot of relevant literature and cases, this paper summarizes the functions, classifications, development history and design principles of rain gardens; puts forward the design strategy of rain gardens among residential areas in Chongqing by combining the field research analysis of residential areas in Chongqing and takes the East Heng Penang as a practice object of design. Conclusions are as follows:(1) It Summed up the ecological, functional, landscape and safety principles of rain garden design in residential areas and pointed out that under the concept of low impact development, the planning and design of residential areas should combine its functions with landscape and make full use of rainwater ecological management in order to playing the ecological effect of green space in residential areas.(2) Through the investigations of rainwater managements of residential areas in Chongqing, after making a targeted analysis for rainwater resources of Chongqing, carrying out field researches on 30 typical residential areas in Chongqing, taking notes on its construction layouts, road forms, types of green space and other characteristics, and analyzing the impacts of factors including rainwater systems, squares, pavements and water features on the effectiveness of ecological rainwater management, the analysis results show that the layouts of residential buildings of Chongqing can be divided into spindle type, master-slave type and point-line type; the road types can be divided into reticular, branched and cyclic; green spaces types can be divided into lower concave type green space, flat ground type green space, slope type green space and upper convex type green space.(3) It raised that the design processes of rain garden in a residential area in Chongqing included "determine the size-layout-location-structure and depth-runoff collection-runoff transport-detailed design-arrangement of plants". It summed up suitable aquatic plants used in rain gardens of Chongqing and proposed the design techniques of extending the runoff routes, reducing impacts of slope and slowing down speed of runoff of mountainous residential areas.(4) It completed the rain garden design of East Heng Penang in Yubei District of Chongqing. Based on low-impact development concept, it carried on a simulation analysis of slope and rainwater runoff catchment targeted residential areas with mountainous terrain in Chongqing by GIS software venues and complete the special design of hierarchical S-shaped rain gardens, permeable tree pool and green wave.