Research On The GIS Auxiliary Method Of Decomposing Control Target In Sponge City Planning

In the process of the City water system development from "water 1.0" to 3.0 "water",impervious surface area increase gradually,blocking the nature urban rainwater infiltration and water self-purification process,caused city is easy to waterlog during the rainy season,city groundwater is not complement,the situation of water pollution is serious.In view of the city water problems above,our country take "sponge" physical properties of water absorption,water storage,water seepage,etc,put forward to build "sponge city",and in a short span of two years(2015-2016)to determine 30 pilot cities,The planning of sponge city is rapidly developing across the country.However,Spongy city planning as a new type of planning,the relevant specifications and construction guidelines are still in the trial stage,and the planning designers are also in the learning stage.In the preparation of the spongy city planning,how to determine the goal of the construction of the sponge City,and how to translate the target into effective indicators and implement it to the city construction is the first question to be considered by the planners.This paper chooses Qujiang,Xi'an and the pilot area of Qujiang as the main research object,and draws on the technical method of suitability evaluation of urban construction land use,and identifies the research area in engineering geology,hydrogeology,topography,land use and ecological environment.The comprehensive evaluation of the factors affecting the control index of the construction of the sponge city(total annual runoff control rate,SS removal rate,subsidence green rate,green roof rate and permeable paving rate)of the study area is analyzed,and the suitability of the study area for each control index is obtained.At the same time,based on the decomposed value of the related control index of the Xi'an Qujiang District spongy City special plan(2017-2030)which has been examined,the appropriate quantitative model is selected and a two function curve is found,so as to decompose the special planning index of the sponge city.