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
Aswan Low Dam in the lower Nile. The dam, originally limited in height by conservation concerns, worked as designed, but provided inadequate storage capacity for planned development and was raised twice, between 1907 and 1912 and again in 1929–1933. These heightenings still did not meet irrigation demands and in 1946 it was nearly over-topped in an effort to maximize pool elevation. This led to the investigation and construction of the Aswan High Dam upstream. The earliest recorded attempt to build a dam near Aswan was in the 11th century, when the Arab polymath and engineer Ibn al-Haytham (known as "Alhazen" in the West)