Water Harvesting in Dry Environments

Abstract

As water shortage in the dry areas is a recurrent crisis, people have a great need for information on how to capture and use every available drop of water efficiently. Water harvesting is an effective and economical means of achieving this objective and information on its various systems and techniques is in great demand. Water harvesting has been practiced successfully for millennia in parts of the world – and some recent interventions have also had significant local impact. Yet water harvesting’s potential remains largely unknown, unacknowledged and unappreciated. Water harvesting offers under-exploited opportunities for the predominantly rainfed farming systems of the drylands in the developing world. It works best in precisely those areas where rural poverty is worst. When practiced well, its impact is to simultaneously reduce hunger and alleviate poverty, as well as to improve the resilience of the environment. Rainfall is the most important natural resource in drier environments. Low rainfall, water scarcity and land degradation severely inhibit the production capacities of agricultural lands in arid and semiarid environments. Improving the efficiency of rainwater use is, therefore, extremely critical in these water-scarce areas with rapidly expanding, poor populations living in a fragile environment and facing food insecurity and depleted natural resources bases. Water harvesting is increasingly important for improving the management of water resources in such dry environments. This chapter deals with the methods and techniques of water harvesting to make more water available to humans, animals and for irrigation purposes, in places where rainwater is the only source of water. Details are provided on the main factors for selection of reliable water harvesting technique that is sustainable under local circumstances, including physical (hydrologic, terrain, and technical), cultural acceptability and socioeconomic (institutional and economic) factors. The aim is to compile a synthesis of experiences that can provide insight into rainwater harvesting opportunities which address human wellbeing while continuing to sustain a range of ecosystem services.