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Impacts of Water Level Rise and Fall of a Hypersaline Lake on Seawater Intrusion: Case of Lake Urmia, Iran

Ghazvini, Faezeh | 2022

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 55107 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Ataie Ashtiani, Behzad
  7. Abstract:
  8. Lake Urmia located in the NW of Iran, has lost 96 percent of its volume in 20 years and become a national crisis. During this shrinkage, the lake level has fallen by 8 m, and its concentration has increased up to 380 g/l. Regarding the vast area Lake Urmia basin is covered, the hydrological characteristics of the basin varies a lot, which affects the aquifers response to the seawater intrusion. In order to study the seawater intrusion in the lake’s aquifer, 18 cases with different hydraulic gradients, hydraulic conductivities and bathymetries were defined. All of these cases were run under three different scenarios in sequence. First, steady state scenario is preformed, then the lake level starts to fall by 8 m and its density increases. In the last scenario, the lake level rises again to its previous location. The results of firs scenario depicts that the main factor impacting the saltwater toe is hydraulic gradients. If the hydraulic gradient and hydraulic conductivity are low, the influence of bathymetry will be tangible. In this situation, when the lakebed slope increases to 2%, the saltwater toe moves 180 m landward. The second scenario results illustrate that in flat cases, the saltwater toe recession lag behind the lake level fall and it take years for it to reach the same position beneath the lake, because the hydraulic gradient is too low to help the water move. The last scenario shows that at the end of the saline-freshwater reaches its previous location at the steady state. The difference between the saltwater toes position in the first and last scenario is 60 m average.
  9. Keywords:
  10. Sea Water Intrusion ; Urumieh Lake ; Hydraulic Gradient ; Hydraulic Conductivity ; Bed Slope ; Sea Level Change ; Sea-Level Fall ; Sea-Level Rise

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