Resumo

NGEBE, Sisipho; MALUNDA, Kasongo Benjamin  e  DU PLESSIS, Anja. Utility of geospatial techniques in estimating dam water levels: insights from the Katrivier Dam. Water SA [online]. 2022, vol.48, n.2, pp.151-160. ISSN 1816-7950.  http://dx.doi.org/10.17159/wsa/2022.v48.i2.3890.

To achieve informed integrated water resource management and sustainability, an understanding of the quantity of water available for use within a spatial and temporal context is needed. This study was consequently focused on the estimation of water levels with the use of geospatial techniques. The availability of water data is a significant challenge, especially for smaller dams used by farmers. The lack of consistent water data in turn poses a problem by limiting the estimation of the overall water availability in water strategy models. This challenge is attributed to the cost of modeling all available water resources and the lack of complete records of all available water resources, as some small dams are not officially registered. This paper provides a simple protocol that can be implemented to reliably derive water levels for dams that are yet to be registered or accounted for, using the Katrivier Dam as a case study. Three main datasets were used which enabled the calculation of water levels - a 12.5 m digital elevation model, Sentinel-2 optical images, and water data from the Department of Water and Sanitation (DWS), as in-situ data. The resulting water level values were derived using a proposed model that includes two correction factors, k and s. The results obtained showed that the estimated water levels from the model proposed in this paper are analogous with those observed by the DWS. Therefore, the proposed method can serve as an additional cost-effective method in water accounting procedures as it requires less expensive equipment than alternatives such as bathymetric methods.

Palavras-chave : water level; Katrivier Dam; modified normalized difference; water index.

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