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UNESCO-IHE Institute for Water Education, Delft (2020)

A comparative assessment of small water storage structures in semi-arid regions as a function of hydro-climatic, geological and socio-economic contexts

Nyathi, Mhambi

Titre : A comparative assessment of small water storage structures in semi-arid regions as a function of hydro-climatic, geological and socio-economic contexts

Auteur : Nyathi, Mhambi

Université de soutenance : UNESCO-IHE Institute for Water Education, Delft

Grade : Master of Science (MS) 2020

Résumé partiel
Semi-arid areas of sub-Saharan Africa are characteristic of high evaporation rates with low and unreliable rainfall. Small water storage structures (SWSS), which include sand dams, micro reservoirs and sand rivers capture runoff and are thus utilised in those areas. During the rainy season, these structures are recharged with water from surface runoff. After cessation of the rains, the communities have a continued water supply for domestic use, livestock watering and for irrigating small gardens. The principle of water storage and optimum site conditions where they are applicable, differs with each SWSS, therefore prompting research. Since research is usually specific to a structure, it becomes difficult for implementers to select the most feasible structure under a given set of conditions. This study assesses the feasibility of the different SWSS, namely sand dams, micro-reservoirs and sand rivers, as a function of the hydro-climatic, geological and socio-economic contexts. The study was based on an inclusive and comparative literature analysis of storage, sedimentation, water quality, costs and management impacts on SWSS. Mapping the potential sites for SWSS and quantitative assessments of storage versus demand and costs was also done using selected case studied in Tete district, Mozambique. Results from potential site mapping of sand dams based on slope, geology and stream order showed a 64 % match with known sites. A low match of 25 % was realised for mapping the potential of micro reservoirs. This shows that the area might not be suitable for constructing micro reservoirs as confirmed by many structures that have failed in the area. For sand rivers, only visual inspection of potential sites was possible based on satellite images. The actual presence of water in these systems would need to be confirmed through additional studies. The mapping objective showed that Geographic Information Systems (GIS) and Remote Sensing (RS) tools can be used for planning water resources development

Sujets  : semi-arid areas water storage satellite data water storage structures site mapping

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Page publiée le 20 avril 2021