Sediment Management for the Nile River in Times of Global Warming

The world ability to store water has peaked at 6800 km3, leaving limited remaining opportunities to build new water reservoirs. It is expected that by 2050; 25% of the volume dedicated to water storage will be filled with sediments. It is estimated that the Aswan High Dam Reservoir in Egypt and Sudan, has been filling up since 1970 at the rate of 130 million m3//year accumulating more than 8 billion cubic meters. The Nile Valley with its numerous dams and reservoirs represents the ultimate challenge for sediment management. The traditional approach of managing sediments in the twentieth century has been to leave a dead storage volume in the reservoir. This classical approach is now considered obsolete and is replaced in favor of four techniques (a) Sediment yield change, (b) Sediment routing (c) Mechanical removal and (d) Combination strategies. Since the construction of the Aswan High Dam in 1970, the flow of sediments into Lower Egypt has diminished by 90%. Losses of farming opportunities are due to sediment starvation and are compounded by rising sea-level due to global warming, adding up to recent neotectonic lowering of the Delta associated with substrate displacement, and ongoing compaction of the Holocene sedimentary sequence. One third of the Nile Delta is already suffering from salinity problems and is expected to become submerged by sea-level rise by 2100. To overcome sediment starvation of the Nile Delta in Lower Egypt, we are proposing a system of bypass pipelines around dams, to transport dredged sediments from the reservoirs. These bypass pipelines, in the form of slurry pipelines or hydraulic capsule pipelines, can transport sediments in a concentrated form and re-inject them downstream the dams of Ethiopia, Sudan and Egypt, be sprayed on lands affected by increase salination at the Nile Delta or at the Mediterranean Coast. We are also proposing the development of international collaboration programs for sediment management between the countries of the Nile Valley on a win–win basis. More particularly the GERD in Ethiopia is expected to produce a limited portion of its potential for power. Ethiopia could be encouraged to let more flow of water downstream the GERD to increase power production as Egypt and Sudan become purchasers of its electricity, while collaborating with sediment management to extend the life expectancy of the GERD. Egypt and Sudan are encouraged to build bypass pipelines around the AHDR while reviving the economy of Upper and Lower Nubia to offset the loss of imports of wheat due to the Russian-Ukrainian war.