Inferring the Joint Operation of High Aswan Dam and Toshka Lakes using Multi-Sensor Satellite Approach

The Nile River Basin (NRB) is a typical example of a transboundary river basin that provides crucial resource for the economy and politics of eleven countries in northeastern Africa. Understanding the reservoir operation in the NRB is crucial to cope with challenges imposed by intense population growth, recurring drought, climate change and increasing competition for water. Data availability to monitor reservoir operation is predominantly an issue, particularly in transboundary basins crossing developing nations, as in the NRB. Such data challenge has been relatively overcome by remote sensing observations that are made available at high spatial and temporal resolutions. Our study implemented a Multi-Sensor Satellite (MSS) approach to understand the reservoir operation in the NRB with the focus on the joint operation of High Aswan Dam (HAD) and Toshka Lakes, located in the south western part of HAD. The MSS approach integrates a suite of satellite observations including Landsat, Sentinel-2, MODIS, satellite altimetry data, and GRACE. The MSS data, along with hydrological model outputs, are used in a water balance model to derive the operation of HAD reservoir and Toshka Lakes. Our study showed that MSS approach has a reasonable skill when modeling the Toshka inflow (i.e., HAD spillway outflow) with an average relative bias -28.5% (averaged for the period 1998-2002) and -6.9% (averaged for the two years 2001-2002). Overall, the MSS approach can potentially assist water managers and dam operators to make more informed decisions in the NRB, especially with the construction of new dams in the upstream countries (e.g., Grand Ethiopian Renaissance Dam; GERD).