Reservoir re-housed, historical artifacts moved or rare environments relocated. Examples include the temples of Abu Simbel (which were moved before the construction of the Aswan Dam to create Lake Nasser from the Nile in Egypt), the relocation of the village of Capel Celyn during the construction of Llyn Celyn, and the relocation of Borgo San Pietro of Petrella Salto during the construction of Lake Salto. Construction of a reservoir in a valley will usually need the river to be diverted during part of the build, often through a temporary tunnel or by-pass channel. In hilly regions, reservoirs are often constructed by
Abu Simbel summer seldom fall below 20 °C. Winters are mild with highs around 25 °C, when temperatures can sometimes fall below 10 °C at night. Precipitation is so rare here that it is impossible to state a "rainy season" for Abu Simbel. In the past, Abu Simbel was located on the west bank of the Nile between the first and second Cataracts of the Nile. Cataracts are rapids caused by boulders or rock sills; they were only passable with difficulty by Nile ship traffic, especially at baseflow. Today both cataracts near Aswan and Wadi Halfa are covered by Lake Nasser, which