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<p>Urban water security in Gondar, Ethiopia, is increasingly threatened by reservoir depletion and distribution inefficiencies. The Angereb Reservoir, the main water source of the city, has experienced significant storage loss, while g rising demand has widened the supply gap. Despite this, the combined i impact of reservoir fluctuations and distribution losses remains poorly understood. This research addresses that gap using a mixed-methods approach that integrates remote sensing and qualitative assessment. Reservoir volume was estimated from Sentinel-2 imagery (2016–2024) using the Normalized Difference Water Index (NDWI) and Modified NDWI, achieving 80–100% accuracy with a kappa coefficient ranging from 0.6 to 1.0 . These data were combined with the ALOS PALSAR digital elevation model to estimate surface–volume relationships. Validation against a bathymetric survey indicated high consistency (MAPE = 0.8%, RMSE = 18,000&#xa0;m<sup>3</sup>). Non-Revenue Water (NRW) was also quantified based on the American Water Works Association (AWWA) water balance framework. Results show a total reservoir storage loss of 19.05% (2.32% annually), with the steepest decline (− 9.72%) occurring between 2022 and 2024. At the seasonal scale, spring exhibited the most severe decline (− 39.3%, annualized − 5.6%), with sharp reductions from winter to spring (18.9–44.9%). Although partial summer recovery occurred, it did not offset overall losses. NRW reached 36.17% (± 1.42%), consisting of 28.41% real losses and 7.71% apparent losses. The combined effects of reservoir degradation and water loss pose a serious threat to Gondar’s water security, requiring coordinated interventions in leak detection, meter upgrading, watershed rehabilitation, and institutional reform.</p>

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Integrated analysis of reservoir storage fluctuations and water loss in Gondar city’s water supply system, Northwest Ethiopia

  • 期刊论文

  • 发表日期：

    2026年1月8日

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  • Getachew Sinku Gessie,
  • Daniel Ayalew Mengistu,
  • Daniel Kassahun Waktola

摘要

Urban water security in Gondar, Ethiopia, is increasingly threatened by reservoir depletion and distribution inefficiencies. The Angereb Reservoir, the main water source of the city, has experienced significant storage loss, while g rising demand has widened the supply gap. Despite this, the combined i impact of reservoir fluctuations and distribution losses remains poorly understood. This research addresses that gap using a mixed-methods approach that integrates remote sensing and qualitative assessment. Reservoir volume was estimated from Sentinel-2 imagery (2016–2024) using the Normalized Difference Water Index (NDWI) and Modified NDWI, achieving 80–100% accuracy with a kappa coefficient ranging from 0.6 to 1.0 . These data were combined with the ALOS PALSAR digital elevation model to estimate surface–volume relationships. Validation against a bathymetric survey indicated high consistency (MAPE = 0.8%, RMSE = 18,000 m3). Non-Revenue Water (NRW) was also quantified based on the American Water Works Association (AWWA) water balance framework. Results show a total reservoir storage loss of 19.05% (2.32% annually), with the steepest decline (− 9.72%) occurring between 2022 and 2024. At the seasonal scale, spring exhibited the most severe decline (− 39.3%, annualized − 5.6%), with sharp reductions from winter to spring (18.9–44.9%). Although partial summer recovery occurred, it did not offset overall losses. NRW reached 36.17% (± 1.42%), consisting of 28.41% real losses and 7.71% apparent losses. The combined effects of reservoir degradation and water loss pose a serious threat to Gondar’s water security, requiring coordinated interventions in leak detection, meter upgrading, watershed rehabilitation, and institutional reform.