Modeling and investigating the effect of the LID methods on collection network of urban runoff using the SWMM model (case study: Shahrekord City)

In recent decades, the accumulation of residential regions has increased due to the expansion of urbanization. This has led to an increase in the impermeable areas and, thus, increasing surface runoff in the cities. Therefore, it is necessary to control surface runoff using Low Impact Development (LID) methods in cities. In this research, using the hydraulic-hydrological SWMM model, the collection network of surface runoff of Shahrekord city was simulated in 2, 5, and 10 years return periods. The calibration of the model was performed in two rainfall events. Afterward, validation was performed using sensitivity analysis with calibrated values, which NSE, RMSE, and% BIAS indices showed good simulation accuracy. After this stage, three methods of the green roof, permeable pavement, and rain barrels were located in 14 selected sub-catchments of Shahrekord. The results of these methods on the volume and peak runoff of selected sub-catchment showed that green roof, permeable pavement, and rain barrels, respectively, reduce the volume and discharge peak runoff by 46, 21, and 25%, on average. Moreover, increasing the rainfall period would increase the effectiveness of using these methods. Also, the results of investigating the value of the discharge and volume of runoff within the drainage canals, the capacity of the canals, and downstream of selected sub-catchment, indicated the reduction of these values due to the application of LID methods. As a result, it was concluded that the effect of using a green roof was greater than the others.