High Dam Authority Chairman Reda Al-Bendari said most studies show the volume of silt accumulated in the High Dam lake amounts to some 4 billion m3, all of which inside the Sudanese borders in the southern part of the lake. Al-Bendari pointed out that according to the dam design, the lake includes three storing capacities. The first, from a level of 85 m3 to 147 m3, contains 31 billion m3 of silt, taking into account that 4 billion m3 of silt have accumulated over the past 50 years and have completely filled this capacity. The chairman said the second capacity, from a level of 147 m3 to 175 m3, contains 90 billion m3, while the third capacity receives 41 billion m3 of water resulting from every new flooding. The total capacity is 162 billion m3 of water with a maximum safety level of 182 meters. Talking to the press yesterday, Al-Bendari said that the quantities of silt accumulated "depend on the contribution of floods", saying that the bigger the floods, the more silt they bring. He pointed out that, according to the studies, it would not be economically feasible to use this silt now unless it started entering the Egyptian borders and were at suitable depths. "Six stations have been set up in the lake to monitor the effects of climate change. These stations control air heat, water temperatures at a certain depth, steam rate and water quality" he added. "The Dam was built by using the best scientific technique. The rocks used are 17 times as many as the ones used to build the Great Pyramid. It is 3,850 m long, 980 m large and 11 m high (50% higher than the Great Pyramid)" he affirmed. He added that the Great Dam has three defensive lines to prevent water leaks. The first line is the "core". It is made of Aswan's clay and is located at a level between 115 m and 186-190 m, which means that this core is higher than the dam maximum level (182 m). He also said the core prevents water leaks. Al-Bendari explained that this core has three tunnels to inspect the High Dam and monitor its conditions. He said these tunnels have devices as old as the dam itself monitoring any movement in its structure. "The second defensive line against water is the protective curtain under the core, at 170 m" he said, adding that this curtain was set up while the Great Dam was being designed. As for the third line, it consists of hoses fixed behind the Great Dam at 114 m. He said their goal is to prevent any water leak and to drain any leaking water into the river to protect the dam structure. Al-Bendari added that "any dam in the world takes into account, in its design, the presence of certain percentages of leaking water, even if the dam is made of cement". He affirmed that the protective curtain lets only 3.5% of water leak out of the dam. As world efficiency estimates stand at 65%, he described the curtain as safe. He explained that according to the latest report on Lake Nasser's water quality, this water is "the best in the world", as salinity is just 160 parts of a million, while there is a high percentage of dissolved oxygen.
