Rainwater harvesting system: a sustainable method for landscape development in semiarid regions, the case of Malayer University campus in Iran

Water scarcity is a big obstacle for developing urban landscapes in cities located in arid and semiarid areas. This issue is very critical in most parts of Iran including city of Malayer. Despite a high rate of physical development, Malayer University campus is suffering from a lack of sustainable water resources for landscape irrigation. Therefore, finding a sustainable water resource for this campus is crucial. Rainwater harvesting system, as an acceptable water resource management method, can be considered as an alternative method for landscape irrigation. Hence, the aim of this study is to determine the suitability and estimate the amount of collectible rainwater in the campus that can be used for landscape irrigation. To achieve these goals, the information such as meteorological data, topography maps, rainwater quality tests, soil experiments, and a land use map of the campus was collected. Then, the amount of collectible water based on the amount of precipitation and the area of non-permeable surfaces was calculated. Based on the average amount of precipitation from 1990 to 2013, we found the potentially collectible rainwater from November to March of each year that can be used in the dry seasons. The volume of collectible rainwater was estimated to be 10,927.7, 17,204.5, and 1392.4 m3 from roofs, roads, and walkways, respectively. Three different scenarios for finding the optimum capacity of cisterns were suggested based on the amount and the periods of precipitation. After analyzing each scenario along with conducting a cost–benefit analysis, the most suitable scenario for the capacity of cisterns was suggested. Finally, based on the location of the non-permeable surfaces, the location of the target green spaces, and topography of the site, the most appropriate locations for placing the cisterns were proposed. As the problem of water shortage and lack of appropriate water resource management is threatening many cities in the developing countries, this study can be beneficial for all those regions.