Aswan Dam have been flooded by Lake Nasser. Before the construction of the High Dam, the Nile deposited sediments of various particle size – consisting of fine sand, silt and clay – on fields in Upper Egypt through its annual flood, contributing to soil fertility. However, the nutrient value of the sediment has often been overestimated. 88 percent of the sediment was carried to the sea before the construction of the High Dam. The nutrient value added to the land by the sediment was only 6,000 tons of potash, 7,000 tons of phosphorus pentoxide and 17,000 tons of nitrogen. These amounts are
Hydropower policy in the United States of 90% efficiency. More importantly, Francis's mathematical and graphical calculation methods advanced turbine design and engineering and allowed confident design of high efficiency turbines to exactly match a site's flow conditions. In the 1870s and deriving from uses in the mining industry, the high efficiency Pelton wheel impulse turbine was developed to use hydropower under very different flow and pressure conditions. Advances in dam design also progressed, with the completion of Old Aswan Dam being considered a milestone of engineering over nature. At the time of its construction, nothing of such scale had ever been attempted: it also became one