Consequences of urbanization on stormwater runoff and its management based on effective factors to choose the optimum scenario.

Land-use has an important effect on the generation of stormwater runoff, and the expansion of urbanization can intensify these conditions and its health and environmental consequences. This study was focused on the urban impact on the Seveso watershed, Italy. The objectives included quantify the effect of urbanization on the generation of stormwater runoff, and choosing the optimum management scenario based on control and prevention variables. Accordingly, the runoff was evaluated based on the Soil Conservation Service (SCS) curve number (CN) method (SCS-CN) by a time series study of four-year precipitation data. Four scenarios were defined based on the available runoff management methods and compared economically. The CN value in the studied polygons was in the range of 62-80, while it was 30-88 based on the soil type. The estimated runoff for the entire study area was 203677103.8 m³, and the most intense runoff caused by rainfall events was 12263398.5 m³. The highest runoff volume contribution (more than 70%) corresponds to industrial and commercial areas. The retention tanks method was not significant effect on flood reduction and increased the environmental risk in the studied scenarios. However, using the sustainable urban drainage system method led to control the environmental risk in the dual method scenario and reduced the volume of stormwater by 30%. It is useful to use combined methods to reduce, control, and treatment of urban stormwater based on volume flow analysis.