| Based on the SWMM model,analyzes the green roof,bio-retention and vegetative swale measured under the condition of rainfall runoff and irrigation under simulated rainfall runoff detention tank data simulation,using SWMM mode to analyze the runoff simulation accuracy and efficiency and the reasons of the errors,and puts forward the optimization and improvement,to give other hydrological model simulation precision research advice in the effect of low flow simulation of estate development.The simulation results of SWMM model show that the model can simulate the runoff peak value.In the five green roof runoff simulation experiment,the peak flow error of peak flow is 9.10%,and the average volume error is 17,31%.Three vegetative swale runoff simulation test average peak flow simulation error is 14.35%,,the average volume error is 0.51%.The average peak flow simulation error is 8.19%,and the average volume error is 1.93%.Integrated four evaluation indicators,the simulation of the ten games in the simulation of R2>0.5,NSE>0.50,0<RSR<0.70,PBIAS is close to the value of zero,which proves that the SWMM model of the LID measures of the flow simulation is better.Because of the precision of SWMM model in the actual demand in the research work of the increase and to explore the mechanism of infiltration equation model is relatively small,based on the SWMM model analysis of seepage formula model and in-depth research,put forward improvement suggestions on Horton infiltration model,water infiltration time substituted in the formula as the arguments the soil,the optimized formula can guarantee that the soil moisture tends to the initial soil moisture,infiltration rate tends to the initial infiltration rate of F0,the soil moisture tends to saturated soil moisture,infiltration rate tends to steady infiltration rate fc.The simulation results of green roof runoff simulation.In the five green roof runoff simulation test,the average simulation error of peak flow is-7.63%,which is about 16.73%lower than that before optimization.The simulated volumetric average error is-2.22%,17.53%less than the optimized one.The four evaluation indicators,five matches in all simulated field simulation R2>0.6,NSE>0.60,0<RSR<0.60,it proved that the improved model in three index accurately 0.1 units,and the PBIAS value decreases by 1 order of magnitude.The results above show that the simulation of LID measures are good ones.The experimental results show that the SWMM model can simulate the outflow of LID well,but there are also space to improve the model.Based on the principle of the optimization model and therefore,the results of the study show that,using the Horton model as the infiltration model itself will bring certain influence to runoff simulation.And the optimization can gives some suggestions in theory and practice on the model optimization algorithm. |
