Aswan Dam insignificant compared to what is needed to reach the yields achieved today in Egypt's irrigation. Also, the annual spread of sediment due to the Nile floods occurred along the banks of the Nile. Areas far from the river which never received the Nile floods before are now being irrigated. A more serious issue of trapping of sediment by the dam is that it has increased coastline erosion surrounding the Nile Delta. The coastline erodes an estimated per year. Before the construction of the High Dam, groundwater levels in the Nile Valley fluctuated 8–9 m per year with the water level
Economy of Egypt border, behind the Aswan High Dam. Just north of Cairo, the Nile spreads out over what was once a broad estuary that has been filled by riverine deposits to form a fertile delta about wide at the seaward base and about from south to north. Before the construction of dams on the Nile, particularly the Aswan High Dam (started in 1960, completed in 1970), the fertility of the Nile Valley was sustained by the water flow and the silt deposited by the annual flood. Sediment is now obstructed by the Aswan High Dam and retained in Lake Nasser. The interruption