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Quantifying the Relative Share of Factors in Drying Gorgan Bay and Miankaleh Peninsula by Studying Long-Term Water Balance

Kazempour, Zahra | 2023

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 56262 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Danesh Yazdi, Mohammad
  7. Abstract:
  8. GB and Miankale Wetland are one of the most valuable water areas in the country from an ecological perspective, providing a habitat for a wide range of aquatic species and birds as well as providing a platform for fishing and tourism for locals. Recently, this wildlife refuge has experienced a crisis of reduced water levels and degraded water quality. Past studies have examined how fluctuations in the Caspian Sea water level affect GB's water quantity and quality. Due to the critical situation of Gorgan Bay, other factors affecting its water balance and upstream basin need to be examined, such as ground water flow and consumption, precipitation, and evaporation, and how they all affect the water volume. It is particularly important for Gorgan Bay's water balance to quantify the interaction between Caspian Sea and GB (GCI). With satellite remote sensing and field data, we quantified the components of the water balance in the water and terrestrial areas of GB between 1998 and 2009. The relative share of each component is determined by the drying of the bay. According to the results of the water balance in upstream basins, the volume of stored water has decreased by -1564 MCM on average, with evaporation and precipitation having the largest shares (55.5 and 44.1%, respectively). GB's water balance has shown a significant descending trend - with an average of 249 MCM - for the interaction of the sea and GB (GCI). Due to the low sea water level and the peak of river inputs to the bay during the cold seasons (October to January), the direction of GCI has been calculated towards the sea on a monthly basis. The results indicate that if the current trend continues with a relative proportion of 52, 21 and 18% for evaporation, GCI, and precipitation, respectively, GB will dry up completely by 2029-2030. This is due to high evaporation, which is 552 MCM per year on average, not compensated by GCI's significant decline. Caspian Sea's fluctuations have also shown strong influences on GB's critical conditions, as evidenced by the 97% correlation between Caspian Sea's water level and the cumulative volume changes. The uncertainty quantification results for GB's water balance show high uncertainty due to volume and sedimentation rate calculations resulting in a CV=1.77 for GCI. In the case that the Caspian Sea continues to experience descending fluctuations due to global climate change and a lack of water for incoming rivers, as well as sedimentation in the channels connecting the sea to the bay, intrabasin management is necessary to control the entry of pollutants from agriculture, industry and urban areas to maintain water quality
  9. Keywords:
  10. Goragan Bay ; Miankaleh Peninsula ; Water Balance ; Uncertainty ; Bay and Sea Water Interaction ; Remote Sensing

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