Nowadays along with the development of society, its impervious areas increase and therefore amount and volume of runoff accrue. Thus flood control in a pedestrian crossing, disorder of transport, contaminant flow and inundation in a residential area are the worry of designer and city manager. The primary goal of this research is simulation and evaluation of urban drainage system of East Eghbal basin which includes part of urban watershed in south and southeast of Mashhad city in Iran. The area of this basin is about 71 Km2. Due of complicacy in the simulation of an urban drainage system, after calibration and validation, MIKE SWMM used for rainfall - runoff simulation and hydraulic response evaluation of urban drainage system. By investigation in historical rains, 17 and 3 storms (include 11 consecutive storms) were selected for single and continues simulation respectively. The rainfall chosen in this study was 30 /4/1998. It had greater peak hydrograph on all sub-catchments. The amount, average intensity, and duration of this rainfall were 14.1 mm and 4.1 mm/hr and 206 min, respectively. The results of the simulation showed that 6 conduits of urban drainage system have difficulty for carrying of the storm water. Finally, based on topographic maps, flooded channels position and surveying the study area, 3 appropriate natural sites for storm infiltration basins were recognized. The uUrban drainage system was evaluated again by the presence of these basins and results showed a noticeable reduction in the flood.

Keywords