Evaluation Method And Its Application For Sponge City Runoff Control Effectiveness

The evaluation of runoff control effect is one of the main problem facing the current construction effectiveness of sponge city.The conventional evaluation methods include monitoring method,model simulation and monitoring-simulation method.Individual monitoring or simulation methods cannot meet the requirements of the evaluation results in terms of accuracy and predictability.Monitoring-simulation method combines the advantages of both monitoring and simulation method,forming complementary advantages and broad application prospects.At present,monitoring-simulation method has less application in the evaluation of runoff control effects.Monitoring-simulation method lack of pertinent research in systematic construction of monitoring network and model parameter values,especially.To solve the above problem,this paper takes evaluation method of the sponge city runoff control effect as the research object.Systematic construction method of monitoring network and the value of the parameters in the evaluation model were researched.On this basis,a method for evaluating the effect of sponge city runoff control using monitoring-simulation method is established,and applied research is carried out in the pilot area of Shenzhen.The thinking of systematic construction of monitoring network and the arrangement principles of monitoring points were analyzed.The basic data needed for evaluation were studied by taking the pilot area of Shenzhen sponge city as an example.The results show that the construction of the sponge city monitoring network needs to systematically arrange the three levels of“source-process-end”.The layout of the three levels of monitoring points needs to meet the principles of practicality,representativeness and economy,etc.The evaluation process requires the data of evaluation object such as runoff indicators,area,slope and feature width,etc.The parameters of three typical sponge facilities:Green roof,Bio-Retention Cell and Permeable Pavement in the SWMM model were screened or determined by Morris screening method and manual trial-and-error method.The results show that the parameters with higher sensitivity to the runoff control effect in the sponge facilities are soil layer parameters.Soil layer porosity and thickness are dominant higher sensitivity parameters,and the sensitivity is above 0.2.The value of soil layer parameters should be considered in the construction process of evaluation model.When the evaluation model of the three sponge facilities will be constructed in Shenzhen,the porosity of soil layer is valued in the range of0.42～0.45,0.55～0.56,and 0.38～0.39,respectively;and the thickness of the soil layer is valued in the range of 86～95 mm,480～490 mm and 320～330 mm,respectively.This will ensure the accuracy of the simulation results.Based on the above research results,the evaluation process of the monitoring-simulation method to evaluate the effect of runoff control and the application in the pilot area of Shenzhen were studied.The evaluation process was formed as follows:research area investigation,monitoring system and evaluation model construction,monitoring implementation,model calibration,monitoring or model simulation and evaluation result calculation.The method of parameters value improves the accuracy of the model simulation results and increases the Nash coefficient E_NS to over 0.7.The construction method of the monitoring network achieves the traceability of evaluating data.The effectiveness of runoff control in the pilot area can be improved by increasing the porosity or thickness of the soil layer in the sponge facilities.