Optimal Use of Rainwater Harvesting: A Strategy to Deal with Water Shortages in Arid and Semi-Arid Regions

Low rainfall with poor temporal and spatial distribution, scarcity of water resources, and the increasing demand for water are major problems in arid and semiarid regions. The efficient use of water resources and efforts to achieve new water sources are two main solutions to slightly overcome these problems. Among these, rainwater harvesting is one of the most prominent methods for rainwater management to confront the scarcity of water that is rapidly developing in many areas. Due to the variety and extent of rainwater harvesting methods, characteristics such as the amount of rainfall and its distribution, topography, soil type, soil depth, social and economic factors, as well as the water consumption in each area must be considered when selecting the appropriate method. In this paper, firstly, the factors affecting the selection and design of each rainwater harvesting method is studied that includes natural factors such as weather conditions, topography, runoff, and the technical, economic, social, and organisational factors. Then, the different methods of rainwater harvesting systems including microcatchment, macrocatchment, and rooftop rainwater harvesting systems are expressed in detail.