Rainwater Harvesting in Residential Areas of Arid and Semi-Arid Regions (Case Study: Torbat-E Jam, Iran)

Nowadays, rainwater harvesting systems, particularly on the roof of the buildings in residential areas could be considered as a managerial procedure to reduce water crisis. This efficient method is being investigated and implemented in different countries all around the world. This study was conducted on the estimation of rainfall, runoff coefficient, and the calculation of the optimized tank volume and the total harvested amount of rainwater on the roofs of the residential areas in Torbat-e Jam. It is noteworthy to mention that the roofs’ surfaces are covered by waterproofing. This study aimed to estimate the amount of the harvested rainwater in the study area, and to apply this method in different areas of Torbat-e Jam, Razavi Khorasan Province, Iran. According to the results, the values of the roofs’ runoff coefficient and average rainfall were 0.9 and 154 mm, respectively. The results of the tank volume sensitivity analysis showed that the average peak 24-hour rainfall is the best rainfall index to calculate the tank volume. The total harvested amount of rainwater was 5,606 m3 considering the total surface of the roofs and the annual rainfall in the study area. Applying this procedure in other areas of Torbat-e Jam, the harvested rainwater was estimated as 772,806 m3. This amount of harvest resulted in 15.5% water saving.