Combining bathymetric measurements, RS, and GIS technologies for monitoring the inland water basins: A case study of Toshka Lakes, Egypt

The current study presents the first bathymetric map of Toshka Lakes in Egypt using the bathymetric method that is based on the combination of in situ measurements, Remote Sensing, and GIS technologies. Such a combination allows an accurate determination of the three-dimensional shapes and volumes of inland water basins, as shown by its implementation in the survey of the Toshka Lakes. The determined total surface area of the Toshka Lakes is 2321.64 km2, holding a cumulative capacity of 53.28 billion m3 (almost equal to Egypt’s annual water income from the Nile). Being today the Toshka Lakes in a mature stage, the results of the morphometric and hypsometric analyses provide useful information for water conservation. The lakes are also expected to gradually shrink in size, similar to what happened in the past decades. Therefore, besides providing a digital database useful for water management, the proposed study is fundamental for appraising, with more realistic expectations, the future changes in the water basins in the Toshka Depression. This article documents the current status of the Lakes and enables researchers and decision-makers to predict their changes in volume and area with depth in the future.