Water Harvesting Structure Sustainability

Abstract

WH comprises all forms of activities where water is collected, stored and used either in the blue or green form. It involves the direct collection of rain that falls onto the roofs, grounds and runs off, as well as floodwater harvesting. Abougoudam District in Chad has been characterized by irregularities in the rainfall intensities with short duration. The district has a long period of the dry season with only four months of rain. The rainfall is unevenly distributed spatially and temporally, therefore, affecting water availability for humans, livestock consumption and off-season irrigation. Water harvesting structures have been proven to provide a cost-effective, environmentally friendly, affordable and relatively simple solution to supplement water for the intended use. The adaptability of sustainable WHSs may increase adoption rate in areas with chronic water shortages through a public-private partnership. The objective of this study was to analyse various water harvesting practices in arid regions and propose sustainable structures that incorporated the technical feasibility, economic and sociocultural acceptability to be implemented in Abougoudam district, Chad and other arid regions of Africa. The probability analysis was used to design rainfall for WH and ArcGIS 10.5 was used to generate the soil map in order to avoid soils that are not suitable for WH. 150 sample questionnaire was administered to the local community of Abougoudam district to assess their willingness to adopt WH. A field survey in Chad and literature review were conducted to assess the best practices. The results from the rainfall analysis revealed that rain with a probability of more than 50% might be considered to supplement water for the intended use. The soil map showed 40 to 60% of vertisols to be avoided for WH. 100% of the local community were ready to adopt WH. The results from the field survey and literature review revealed that water spreading weirs, Hafir system, Sand dam, permeable rock dam, rooftop, Zai pit and Stone lines are the best practices that could be adaptable in Chad and most specifically in Abougoudam District but water spreading weir, Sand dam and combination of the zaï pit and stones lines were more preferable. This was because of their capacity to regenerate degraded lands in valley regions, reduce evaporation and recharge groundwater. Hafir system is also considered because of their potential to provide water both for human and livestock. The sustainability of these structures could be addressed by incorporating the policy brief developed at the end of this study into the national policy