Rise and demise of the New Lakes of Sahara
Rise and demise of the New Lakes of Sahara
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DOI：
10.1130/ges00142.1
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发表时间：
2008-04-01
期刊：
影响因子：
2.5
通讯作者：
Alfarhan, Mohammed
中科院分区：
文献类型：
--
作者：
Abdelsalam, Mohamed G.;Youssef, Ahmed M.;Alfarhan, Mohammed
多光谱遥感数据和数字高程模型被用于研究埃及南部撒哈拉新湖的时空演变。这些湖泊出现于1998年9月，当时由于埃塞俄比亚高地的高降水量导致纳赛尔湖水位异常上升，湖水向西北方向流向图什卡洼地。五个湖泊形成于当地的洼地，下面是不透水的古新世页岩和白垩地层。湖泊的发展经历了三个阶段。(1)1998年9月至2001年8月为上升阶段，湖泊覆盖面积达到1586 km（2）。在这一阶段，水的供应速度远远超过了蒸发损失的速度。这一阶段的特点是早期阶段（1998年8月至1999年8月），湖泊覆盖面积以每月75平方公里的速度增加。随后是后期阶段（1999年8月至2001年8月），面积平均增加约28 km（2）/月。(2)2001年8月至2003年8月为稳定状态阶段，在此期间湖泊覆盖面积保持相对不变，蒸发损失的水量不断被纳赛尔湖的供水所补充。(3)从2003年8月到2007年4月，纳赛尔湖的供水完全停止，水不断蒸发。湖泊覆盖面积减少到约800平方公里，平均损失约17平方公里/月。如果这一趋势继续下去，到2011年3月，撒哈拉新湖将完全消失。撒哈拉新湖的空间分布强烈地受形态上确定的东、北、东北和西北走向断层的控制。撒哈拉新湖对努比亚含水层的补给微不足道;大部分湖区位于不透水层之上。
Multispectral remote sensing data and digital elevation models were used to examine the spatial and temporal evolution of the New Lakes of Sahara in southern Egypt. These lakes appeared in September 1998, when water spilled northwestward toward the Tushka depression due to an unusual water rise in Lake Nasser induced by high precipitation in the Ethiopian Highlands. Five lakes were formed in local depressions underlain by an impermeable Paleocene shale and chalk formation. The lakes developed through three stages. (1) A rise stage occurred from September 1998 to August 2001; the area covered by the lakes reached similar to 1586 km(2). In this stage the rate of water supply far exceeded the rate of water loss through evaporation. This stage was characterized by an early phase (August 1998-August 1999) when the area covered by the lakes increased by similar to 75 km(2)/month. This was followed by a late phase (August 1999-August 2001), in which area increase averaged similar to 28 km(2)/month. (2) A steady-state stage occurred from August 2001 to August 2003, during which the area covered by the lakes remained relatively unchanged and water lost through evaporation was continuously replaced by water supply from Lake Nasser. (3) A demise stage occurred from August 2003 to April 2007, during which water supply from Lake Nasser stopped completely and water was continuously evaporating. The area covered by the lakes decreased to similar to 800 km(2) with an average loss of similar to 17 km(2)/month. If this trend continues, the New Lakes of Sahara will disappear completely by March 2011. The spatial distribution of the New Lakes of Sahara is strongly controlled by morphologically defined east-, north-, northeast-, and northwest-trending faults. The water recharge of the Nubian aquifer by the New Lakes of Sahara is insignificant; much of the lakes' area is above an impermeable formation.