Are rain floods a seasonal disaster or a blessing in disguise, asks Nader Noureddin* Rain floods are heavy rain precipitation in a short time that exceeds the soil water holding capacity, water penetration and soil saturation capacity. This huge amount of rainy water accumulates and begins to move, causing soil erosion and sweeping away everything in its path. The existence of high mountains in flood areas increases the speed of the water stream. High altitude and sharp slopes give floodwaters extra damage power. Areas exposed to rain floods in Egypt are well known, identified hundreds of years ago. Such areas extend along all Upper and Middle Egypt governorates from Aswan to Giza in addition to Sinai and the Red Sea coast. These areas are protected by a wide flood drain surrounding them, ending up in the River Nile in the Nile Valley and Delta, or in the Mediterranean Sea, on the Northern Coast, and the Red Sea coast in South Sinai. These drains should be cleaned out regularly to make sure that the way of the flood stream is clear before predicted heavy rain between October and March, and also between May and June. Some Bedouins who live in Sinai and on the Red Sea coast capture flood water during the rainy season and release the water during times of drought through deep, wide and cemented wall and ground drains called harrabat, or rain water traps. These flood traps are usually dug near the bottom of mountains to gain the maximum amount of floodwater and reduce water speeds to limit its damage power. These floodwaters help cover the Bedouins' irrigation demands throughout the year. Some open areas in North Sinai have small dams -- such as the six-metre high Rawafaa dam -- to make water reservoir and to protect the open area from flood streams. Astonishingly, rain floods have not occurred for the last 10 years, which encouraged several mistakes to be made: many buildings and houses were constructed over the drains or mekharat. No attention was given to cleaning flood drains regularly. Further, the General Authority of Weather Prediction makes little use of information that can predict rain floods four days before they occur -- a period long enough to take the necessary measures required to avoid damage. Most Upper Egypt governorates, especially Aswan, Sohag and Assiut, need to dig wide trenches near the bottoms of mountains to work as flood traps. North and South Sinai also need to build more dams to make reservoirs that serve dry areas and control and minimise flood damage. Electricity towers and petroleum tanks in Aswan and Sohag must also be moved away from flood paths and the construction of houses or factories over flood drains should be prohibited. Regular cleaning of flood drains should begin in October and be done frequently throughout the raining season. * The writer is professor of water and soil sciences at the Faculty of Agriculture, Cairo University.
