Effects of Low-impact Development of Infiltration and Storage Facilities on Urban Runoff Management in City of Sanandaj

In recent years, low-impact development (LID) has been well established as a method to provide the best and most affordable solutions for managing and alleviating the negative impacts of urban floods. Application of this practical method is regarded as a major step toward sustainable development as it employs eco-friendly storage instruments, reduces the effects of urbanization on impervious surfaces, and helps water infiltration to recharge groundwater resuorces. Although low-impact development tools have proved effective in the management of surface water resources and conservation of water quality, finding proper locations for the deployment of the equipment and the optimal use of each tool are still questions of much controversy and no definitive solutions are provided yet as environmental conditions keep changing. The present study exploits bio-retention cells, rain barrels, green roofs, and vegetable swales as storage instruments under different rainfall scenarios with return periods from 2 to 100 years extracted from the statistical data of Sanadaj City to determine the flood volumes and hydrographs for each sub-basin before and after the low-impact development tools are employed. Moreover, SWMM 5.1 software developed by the American Environmental Protection Agency is used to develop hydraulic and hydrologic models of the basin and the changes are monitored with each development tool selected. The most outstanding results obtained from this study include the change observed in thet form of hydrograph, a reduction of 50% in time of concentration, and reductions of 35 to 50% in peak flow in the city of Sanadaj as a result of employing the low-impact development method. Conclusion: Classification of the equipment into infiltration and storage tools used for urban runoff control allows the best runoff control model to be developed such that the grounds are prepared not only for the return to the conditions before a certain development took place but even for flood management in challenging and riskful urban areas.