Simulation and comparison of urban water flow in two land use modes using SWMM model, Case study: Jahrom urban watershed
Subject Areas : KARBARI ARAZI
1 - Department of civil Engineering, Larestan Branch, Islamic Azad University, Larestan,Iran
Keywords: Urban watershed, Land use, SWMM, Calibration, Sensitivity analysis.,
Abstract :
Floods and flooding in urban areas caused by intense rain events has created problems for entire cities. Increasing urbanization, changes in land use, construction unprincipled and impervious land development on vulnerable areas have important effects on the occurrence of this risk. The Storm Water Management Model (SWMM) is a hydrodynamic model for simulating urban drainage and runoff, which is widely used for different designs and analyses. In this article, two types of land use (years 1344 and 1400) of Jahrom city were selected to study the characteristics of water runoff for 5 rainfall events. The sensitivity analysis of runoff production parameters was performed and the optimal parameters were determined using the SWMM model. The results of the land use change study showed that the biggest change is related to the conversion of gardens and rangelands into residential and commercial lands, so that the area of urban gardens has decreased 5 times, and this factor has caused an increase in the volume of urban flooding. Also, after the validation and calibration of the SWMM model, the Nash-Sutcliffe efficiency (NSE) was equal to 0.88 and the R2 value was equal to 0.91, which shows the efficiency and suitability of the model for Jahrom urban basin. Finally, the results of the sensitivity analysis also showed that the parameters of the imperviousness and the depression storage were the most sensitive in the peak flood discharge and Manning's roughness coefficient had the least effect.