A Preliminary Study On The "Four Step" Approach To The Combination Of Natural Terrain In The Northern Sponge City Planning

After 2013,the preparation of the "sponge city planning" with the control index of "annual runoff control rate" was carried out in the whole country.Many of them are planning,but some planning,perhaps because of tight time,heavy task,and failed to effectively control the total annual runoff.In the sponge city planning,due to sponge city planning and natural terrain fit is not enough,may lead to additional waste of construction funds,or reduce the effectiveness of sponge facilities,sponge system affect the ecological effects of play.This paper first analyzes how the natural terrain affects the planning and construction of sponge city,including the influence of natural terrain on rainfall,snowmelt and evaporation,the influence of natural terrain on surface water distribution,the influence of natural terrain on groundwater,Different natural terrain may cause natural disasters,artificial changes after the impact of natural terrain.Then,this paper further analyzes the causes and consequences of common terrain omission.Finally,based on the experience of domestic and foreign counterparts,this paper puts forward a set of four-step method for sponge city planning in northern China.The method emphasizes more fit with natural terrain,integrated use of ArcGIS and hydrological simulation software SWMM.The fourth step: the use of scientific analysis methods,the proposed water system construction methods and reasonable overall indicators,based on ArcGIS and the "four-step" sponge city special planning method,that is,the first step: a complete grasp of terrain basic data;SWMM comprehensive analysis to determine the natural watershed and municipal catchment area and the corresponding control indicators;the third step: according to terrain conditions,select a reasonable economic sponge facilities,check whether the plots meet the overall indicators;Two or three steps on the basis of the combination of other planning factors on the terrain of the contradictory needs,and reverse to the first step,or to be refined.This method clearly puts forward the acquisition method of topographic data and the method of terrain data processing to solve the problem of limitation of natural terrain acquisition and analysis methods.On the basis of fully grasping the terrain data,SWMM is used to evaluate the present drainage system,and the method of determining the natural terrain conditions and the existing drainage system is put forward.Trying to make this research on the sponge city planning has some guiding significance and reference.This "four-step" sponge city planning method in the city of sponge city planning project in Xi'an has been the initial use,to a certain extent,an increase of sponge city special planning system of scientific.