Aswan Dam assumption did not take into account the extent of perennial irrigation that was already present throughout Egypt decades before the high dam closure. By the 1950s only a small proportion of Upper Egypt had not been converted from basin (low transmission) to perennial (high transmission) irrigation. Expansion of perennial irrigation systems in Egypt did not depend on the high dam. In fact, within 15 years of the high dam closure there was solid evidence that biharzia was declining in Upper Egypt. S. haematobium has since disappeared altogether. Suggested reasons for this include improvements in irrigation practice. In the Nile Delta,
Aswan Dam to fund construction of the High Dam. When the Suez War broke out, the United Kingdom, France, and Israel seized the canal and the Sinai, but pressure from the U.S. and the USSR at the United Nations and elsewhere forced them to withdraw. In 1958, the USSR went ahead in providing support for the High Dam project. In the 1950s, archaeologists began raising concerns that several major historical sites, including the famous temple of Abu Simbel were about to be under water. A rescue operation began in 1960 under UNESCO (for details see below under Effects). The Soviets also provided