Abstract:

Rainwater utilization is a means used to lessen urban water shortage and reduce waterlogging disasters.Based on a large scale of topographic map data (1〖DK〗∶500) and the rainfall data of Nanjing,the volume of available harvesting rainwater in a year with different guaranteed ratio of rainfall and the potential for surface runoff volume reduction are calculated in a community in Nanjing.Then,an analysis of cistern setting feasibility is performed under four principles.The results show that the annual collectable rainwater is approximate 114 2721 m3 with the guaranteed ratio of rainfall at 50%.And urban waterlogging disasters could be effectively reduced by rainwater harvesting.214% and 112% of runoff volume could be reduced by roof rainwater utilization in two cases of 50 mm and 955 mm respectively (the average annual maximum daily rainfall).The roof area which is suitable to set cisterns is 55% of the total roof area,while the availability rate  reached about 77% for residential and the other types of buildings’ roof areas.