Feasibility Study of Rainwater Harvesting from Large Rooftops (Case Study: Ahvaz City, Iran)

Humanity is currently facing one of its greatest challenges a shortage of renewable and accessible water resources. One of the best and most cost-effective solutions for sustainable water resource utilization is rainwater harvesting system (RWS). Rooftops of buildings can act as water micro-catchment surfaces and store rainwater before it turns into runoff losses. In order to investigate the potential of rainwater conservation and recycling, in this study, the feasibility of utilizing rainwater harvesting from rooftops of public and large buildings of Ahvaz city was evaluated. To achieve the goal, we utilized annual precipitation data, the Statistical Yearbook of the Ahvaz Metropolitan Area, and satellite imagery from Google Earth. Large buildings were categorized into 6 groups, and the total rooftop area suitable for implementing a rainwater harvesting system was estimated. It was calculated that approximately 222,708 m3 of rainwater could be harvested annually from the rooftops of these buildings. The volume of harvestable water was distributed among different building categories, with industrial sites having the largest share, followed by governmental offices and educational centers. The results form the Sotnikova equations showed that by help of RWS could meet 11.42% of Ahvaz's industrial water demand, leading to a reduction in dependency on external water sources and economic savings. Recycled rainwater could supply up to 34.56% of the water demand for urban parks in Ahvaz.