Sefelnasr Ahmed, Sherif Mohsen
Geology Department, Faculty of Science, Assuit University, 71516 Assuit, Egypt;
Ground Water. 2014 Mar-Apr;52(2):264-76. doi: 10.1111/gwat.12058. Epub 2013 Apr 18.
Several investigations have recently considered the possible impacts of climate change and seawater level rise on seawater intrusion in coastal aquifers. All have revealed the severity of the problem and the significance of the landward movement of the dispersion zone under the condition of seawater level rise. Most of the studies did not consider the possible effects of the seawater rise on the inland movement of the shoreline and the associate changes in the boundary conditions at the seaside and the domain geometry. Such effects become more evident in flat, low land, coastal alluvial plans where large areas might be submerged with seawater under a relatively small increase in the seawater level. None of the studies combined the effect of increased groundwater pumping, due to the possible decline in precipitation and shortage in surface water resources, with the expected landward shift of the shore line. In this article, the possible effects of seawater level rise in the Mediterranean Sea on the seawater intrusion problem in the Nile Delta Aquifer are investigated using FEFLOW. The simulations are conducted in horizontal view while considering the effect of the shoreline landward shift using digital elevation models. In addition to the basic run (current conditions), six different scenarios are considered. Scenarios one, two, and three assume a 0.5 m seawater rise while the total pumping is reduced by 50%, maintained as per the current conditions and doubled, respectively. Scenarios four, five, and six assume a 1.0 m seawater rise and the total pumping is changed as in the first three scenarios. The shoreline is moved to account for the seawater rise and hence the study domain and the seaside boundary are modified accordingly. It is concluded that, large areas in the coastal zone of the Nile Delta will be submerged by seawater and the coast line will shift landward by several kilometers in the eastern and western sides of the Delta. Scenario six represents the worst case under which the volume of freshwater will be reduced to about 513 km(3) (billion m(3) ).
最近有几项研究探讨了气候变化和海平面上升对沿海含水层海水入侵的可能影响。所有研究都揭示了该问题的严重性，以及在海平面上升情况下弥散带向陆地移动的重要性。大多数研究没有考虑海平面上升对海岸线向内陆移动的可能影响，以及随之而来的海边边界条件和区域几何形状的变化。在平坦、低地的沿海冲积平原地区，这种影响更为明显，在海平面相对较小的上升情况下，大片区域可能会被海水淹没。没有一项研究将由于降水可能减少和地表水资源短缺导致的地下水抽取增加的影响，与预期的海岸线向陆地移动结合起来。在本文中，使用FEFLOW研究了地中海海平面上升对尼罗河三角洲含水层海水入侵问题的可能影响。模拟是在水平视图中进行的，同时使用数字高程模型考虑海岸线向陆地移动的影响。除了基本运行（当前条件）外，还考虑了六种不同的情景。情景一、二和三假设海平面上升0.5米，而总抽水量分别减少50%、保持当前条件不变和增加一倍。情景四、五和六假设海平面上升1.0米，总抽水量的变化与前三种情景相同。根据海平面上升情况移动海岸线，因此相应地修改研究区域和海边边界。得出的结论是，尼罗河三角洲沿海地区的大片区域将被海水淹没，三角洲东西两侧的海岸线将向陆地移动数公里。情景六代表了最糟糕的情况，在这种情况下，淡水量将减少到约513立方千米（十亿立方米）。
