Aswan Low Dam was summoned to Egypt by the Fatimid Caliph, Al-Hakim bi-Amr Allah, to regulate the flooding of the Nile, a task requiring an early attempt at an Aswan Dam. After his field work convinced him of the impracticality of this scheme, and fearing the Caliph's anger, he feigned madness. He was kept under house arrest from 1011 until al-Hakim's death in 1021, during which time he wrote his influential "Book of Optics". Following their 1882 invasion and occupation of Egypt, the British began construction of the first dam across the Nile in 1898. Construction lasted until 1902, and it was opened
Aswan average relative humidity of only 26%, with a maximum mean of 42% during winter and a minimum mean of 16% during summer. The weather of Aswan is extremely clear, bright and sunny year-round, in all seasons, with a low seasonal variation, with almost 4,000 hours of annual sunshine, very close to the maximum theoretical sunshine duration. Aswan is one of the sunniest places on Earth. The highest record temperature was on July 4, 1918, and the lowest record temperature was on January 6, 1989. In 1999, South Valley University was inaugurated and it has three branches; Aswan, Qena and Hurghada.