Evaluation of small scale water harvesting techniques for semi-arid environments

Abstract

Water harvesting is widely practiced and is expected to improve water availability for domestic and agricultural use in semi-arid regions. New funds are becoming available to stimulate the implementation of water harvesting projects. We review the literature to gain insight regarding characteristics that describe and determine the success of selected water harvesting techniques. We assemble a database containing key characteristics of water harvesting techniques, based on studies published in scientific journals and in reports of international organisations. In addition to the literature also information obtained from practitioners is considered. Physical characteristics, costs, and governance needs of the different techniques are evaluated. Results show that large water harvesting structures (>500 m3) are less expensive than small structures, when taking into account investment costs, storage capacity and lifetimes. Their costs are comparable to the costs of large scale reservoirs. The governance, technical knowledge and initial investment, are, however, more demanding for the larger structures than for smaller structures. To support the implementation of water harvesting projects in selecting appropriate techniques, we present a decision framework for choosing water harvesting techniques based on case-specific characteristics. This framework can also be used when reporting and evaluating the performance of water harvesting techniques.