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

<p>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).</p>

The Value of Long-term Streamflow Forecasts in Adaptive Reservoir Operation: The Case of High Aswan Dam in the Transboundary Nile River Basin

Transboundary river basins are experiencing extensive dam development that challenges future water management, especially for downstream nations. Thus, adapting the operation of existing reservoirs is indispensable to cope with alterations in flow regime. We proposed a Forecast-based Adaptive Reservoir Operation (namely FARO) framework to evaluate the use of long-term climate forecasts in improving real-time reservoir operations. The FARO approach was applied to the High Aswan Dam (HAD) in the Nile river basin. Monthly precipitation and temperature forecasts at up to 12 months of lead time are used from a suite of eight North American Multimodel Ensemble (NMME) models. The value of NMME-based forecasts to reservoir operations was compared with perfect and climatology-based forecasts over an optimization horizon of 10 years from 1993 to 2002. Our results indicated that the forecast horizon for HAD operation ranges between 5- and 12-month lead time at low and high demand scenarios, respectively, beyond which the forecast information no longer improves the release decision. The forecast value to HAD operation is more pronounced in the months following the flooding season (October through December). During these months, the skill of streamflow forecasts using NMME forcings outperforms the climatology-based forecasts. When considering the operation of upstream Grand Ethiopian Renaissance Dam (GERD), using streamflow forecasts minimally helps to maintain current target objectives of HAD operation and therefore result in higher operation costs as opposed to current conditions without GERD. Our study underlined the importance of deriving a new adaptive operating policy for HAD to improve the value of available forecasts while considering GERD filling and operation phases.

Understanding and managing new risks on the Nile with the Grand Ethiopian Renaissance Dam

When construction of the Grand Ethiopian Renaissance Dam (GERD) is completed, the Nile will have two of the world’s largest dams—the High Aswan Dam (HAD) and the GERD—in two different countries (Egypt and Ethiopia). There is not yet agreement on how these dams will operate to manage scarce water resources. We elucidate the potential risks and opportunities to Egypt, Sudan and Ethiopia by simulating the filling period of the reservoir; a new normal period after the reservoir fills; and a severe multi-year drought after the filling. Our analysis illustrates how during filling the HAD reservoir could fall to levels not seen in recent decades, although the risk of water shortage in Egypt is relatively low. The new normal will benefit Ethiopia and Sudan without significantly affecting water users in Egypt. Management of multi-year droughts will require careful coordination if risks of harmful impacts are to be minimized.

Regime equations development for the design of Egyptian sandy canals

The construction of the High Aswan Dam in Egypt led to reducing the solids suspension in water from more than 3,500 p.p.m. to less than 100 p.p.m. As the regime of Egyptian canals has been changed completely after the construction of the High Aswan Dam, the previous derived equations are not applicable any more, and using them leads to a shortage in the carrying capacity of the canals. In the current study, extensive field measurements have been carried out on 15 stable Egyptian canals, which cover various discharges of irrigation canals with sandy soils starting from 5 m3/s to 50 m3/s and d50 ranging from 0.196 to 0.538 mm. Then, applicable regime relationships for designing stable sandy channels were determined. The new equations are useful for designing new stable canals and redesigning unstable canals within the same range. The new regime equations were verified by using the HEC- RAS program. Finally, sensitivity analysis has been performed in order to investigate the effect of changing the deduced parameters on the discharge.

Effect of Grand Ethiopian Renaissance Dam on the Water Footprint of Aswan High Dam Hydropower

Construction of the Ethiopian Grand Renaissance dam (GRD) has many impacts and implication on the water share and future use in Egypt. Especially the period of the reservoir filling will have a great effect on the Nile River and its water in Egypt. Many of these effects of the GRD on Egypt has been studied before, but no study was done on the effect of its existence on the hydropower water footprint of the High Aswan dam. This research is concerned by simulating the effect of the different GRD reservoir filling scenarios on the water footprint of the hydropower generated from the High Aswan dam. Also, the effect on the hydropower of the Aswan dam itself is also simulated and assessed. Mathematical modeling is used to reach those goals. Three filling scenarios of the GRD were investigated: namely 3 years, 5 years, and 6 years. It was found that as the filling duration of the GRD decreases the negative effect on the hydropower water footprint increases.

From individualistic behavior to full cooperation: optimal management policy design under varying cooperation levels in the Nile River basin

<p>Transboundary river basins worldwide are commonly managed by unique, institutionally independent decision makers and characterized by multiple stakeholders with conflicting interests, including distribution, co-management, and use of water resources across sectors and among countries. This competition is expected to exacerbate in the future due to climate change induced water scarcity, increasing demand, and the development of infrastructure, which is often criticized for potentially jeopardizing downstream security by affecting water supply, irrigation, and energy production. </p><p>The Nile River basin is an emblematic transboundary basin, encompassing 11 countries and home to one-third of the African population. The largest fraction of Nile River streamflow originates in Ethiopia and is conveyed into the system via the Blue Nile. However, the larger water users have historically been downstream, in particular Egypt, where the High Aswan Dam (HAD) constitutes the backbone of Egyptian electricity supply and enables the irrigation of vast agricultural districts. This geographic disparity between water origination and consumption provides both the potential for conflict and the rationale for cooperation. Currently, the ongoing construction of the soon-to-be largest dam in Africa, the Grand Ethiopian Renaissance Dam (GERD) on the Blue Nile, is highly debated given concerns rising from how it will affect water supply and power generation in downstream countries. However, GERD may represent a response to the frequent regional power shortages, foster economic development, and represents a unique opportunity for cooperation between riparian countries from which all parties can benefit.</p><p>In this work we explore how varying levels of cooperation among the riparian countries, from individualistic behavior to full cooperation, might impact hydropower production and irrigated agriculture in the Nile River basin. We use an Evolutionary Multi-Objective Direct Policy Search approach to design optimal operation of a three-dimensional reservoir system, including GERD (Ethiopia), HAD (Egypt), and Merowe Dam (Sudan), under historical hydro-climatic conditions and under different cooperation levels, assuming the capacity of re-optimization of the High Aswan Dam and the Merowe Dam. Expected results may illustrate the benefits of implementing a centralized rather than an individualistic strategy, highlighting the value of full information exchange and of basin-wide cooperation.</p>