Study of the Potential for Harvesting Rainwater in Urban Watersheds (Case study: City of Mashhad)

Since the rainwater is the cleanest part of water resources in nature، if the runoff is collected and used، consumers would get involved in the process ofwater resources managementin addition to saving water. Estimation of the runoff volume، particularly in urban areas، is the main parameter. Due to the lack of or inadequacy of data، often this parameter is estimated using experimental methods which have been mostly developed for other areas. Moreover، these methods would not work properlywithout proper calibration and performance evaluation. In this study، a research project has been implemented in Building No. 2 of the Khorasan Agricultural and Natural Resources Research Center. In this project، a rain gauge and runoff gaugewere installed، and the runoff and the rainfall was recorded. Using appropriate statistical analyzes، the runoff coefficient and the volume of runoff by different values of the depth and intensity of rainfall were measured after each rainfall event. Based on these results، the runoff coefficient for the average spring rainfall events is 0. 52; it is 0. 59 for the fall season is 0. 59 and it is 0. 60 for the winter. The highest average amount of runoff was generated in winter. The average potential runoff produced from one Hectare of paved streets in the study area، in each of the seasons of fall، winter، and spring is about 200 cubic meters.