Analysis of Rooftop Rainwater Harvesting in Kabul New City: A Case Study for Family Houses and Educational Facilities

The Afghan government has planned the project of Kabul New City (KNC) to cope with the rapid growth of Kabul, an existing capital city. Due to climatic and topographical reasons, it is supposed that KNC suffers from a water scarcity problem. This study investigates the feasibility of a rooftop rainwater harvesting system in KNC to relieve the water scarcity problem. An applicability of the rooftop rainwater harvesting system was discussed for several types of residential houses and schools, using 11 years rainfall data. This study also examined the cost-effectiveness of the system by considering the service life of the system. Furthermore, an optimal size of the rainwater storage tank was discussed based on the balance among harvested rainwater volume, non-potable water demand, and cost-effectiveness.