Evaluation Of Sponge City Planning Based On Info Works ICM Model In Shuiyang Ecological New District In Loudi

Sponge city is the urban developed concept which the govermment promotes.Compared with the traditional mode of the urban development,the construction of sponge city will make the charge of drainage system and waterlogging caused by rainfall reduced.But it is hardly to evaluate the reduction of the charge of drainage system and waterlogging caused by rainfall which is caused by the construction of sponge city.The emphasis of this paper is evaluating the effect of sponge city by making use of the computer to establish drainage models.The writer establishs the drainage model according to the actual situation of the shuiyang Ecological new District in Loudi in this paper and analyses the sensitivity of model parameter according to Morris method.The writer finally determines the model parameter by analyzing comprehensively the domestic drainage model.To sort by sensitivity of the model parameters for the total runoff volume of the study plot in dscending order,the order is the runoff coefficient,the initial loss of rainfall,the confluence parameter and the manning’s N of conduit.To sort by sensitivity of the model parameters for the peak flow of the conduit in dscending order,the order is the runoff coefficient,the manning’s N of conduit,the confluence parameter and the initial loss of rainfall.The values of each parameter of the drainage model before the construction of sponge city are as follows.The values of the of the confluence parameter of road and roof are 0.011,and the value of the of the confluence parameter of grassland confluence is 0.2;The values of the runoff coefficient of roof and pavement are 0.8,and the value of runoff coefficient of grass is 0.15.The initial loss of rainfall of the roof and road are 0.000071m,and the initial loss of rainfall of the grassland is 0.0025;The value of the manning’s N of conduit is 0.0015.The values of each parameter of the drainage model after the construction of sponge city are as follows.The values of the of the confluence parameter of road is 0.012.The values of the of the confluence parameter of roof is 0.014,and the value of the of the confluence parameter of grassland confluence is 0.2;The values of the runoff coefficient of roof and pavement are 0.8,and the value of runoff coefficient of grass is 0.15.The initial loss of rainfall of the roof and road are 0.000071m,and the initial loss of rainfall of the grassland is 0.0025;The value of the manning’s N of conduit is 0.0015.Analysing the result of the drainage model,the conduit’s ability of discharging the rainfall is improved largely afer establishing low impact development facilities in the study plot.When the study plot does not establish the low impact development facilities,there are 11.3%of drainage pipes whose drainage capacity is less than once a year,and there are 73.2%of the drainage pipes whose drainage ability are more than once every 30 years.When the study plot establishs the low impact development facilities,there are 0.7%of drainage pipes whose drainage capacity is less than once a year,and there are 89.2%of the drainage pipes whose drainage ability are more than once every 30 years.For the peak flow of the conduits,the cut-rate of peak flow of the branch conduits is greater than the main conduits’,and the cut-rate of peak flow of the front conduits is greater than the last conduits’.For the level of waterlogging,it can be found that the low impact development facilities make the area of waterlogging dramatically cut.The cut rate is over 80%,and some cut rate is 100%.Through the evaluation,it was found that the special planning of the sponge city in the shuiyang Ecological new District in Loudi could not meet the design standard of waterlogging for the area under the condition of the rainfall whose return period is once every 30 years.According to the results of the model operation and the conditions of the topography of the shuiyang Ecological new District in Loudi,three new storage tanks and four stormwater drainage passages were disigned.The research results can provides the shuiyang Ecological new District in Loudi a reliable basis for urban construction in this paper,and it can also offer other area experience for evaluating the effect of the sponge city.