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Quantitative and Qualitative Assessment of Wetlands in Iran by Remote Sensing

Abbasalizadeh Rezaie, Parisa | 2023

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 56184 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Danesh Yazdi, Mohammad
  7. Abstract:
  8. Many of Iran's wetlands are going dry because of the expansion of anthropogenic activities like the exorbitant withdrawal of groundwater resources and excessive use of water for agricultural purposes. Bakhtegan, Hoor-ol-azim, Anzali, and Miankaleh are some of the most notable examples of this issue in the past two decades. The crucial role of wetlands in preserving the biodiversity of flora and fauna and supplying groundwater resources necessitates continuous monitoring of the quantitative and qualitative changes in the surface water of wetlands. The main focus of this research is quantifying the reduction in wetlands' surface water using K-means and random forest algorithms based on satellite images of Landsat series and identifying the changes made in water quality indicators such as the concentration of chlorophyll-a using the NDCI index derived from Sentinel-2. The main challenges of processing satellite images for detecting surface water of wetlands include the difference in vegetation types, variations in water level for each month of a year, extreme shallowness, and specific colors in some of the wetlands, each of which introduces errors in the process of detecting water bodies. Some of the most remarkable achievements of this study include attaining the quantitative and qualitative changes in all of the inland and coastal wetlands of the country for the first time and presenting a comprehensive set of instructions to extend the usage of the resultant combinations of spectral indices to wetlands with similar physical attributes. The results show that wetlands water areas (WWA) have significantly descended in the past two decades. The minimum amount of WWA happened in 2015 with 4730 square kilometers area, which indicates 5197 square kilometers loss of surface water area compared to the maximum WWA recorded between 2003 to 2021. The highest reduction and increase in the total surface water area were related to the Urmia Lake -third order- subbasin with a 108.78 decreasing rate and the Jarahi subbasin with a 7.25 increasing rate. The Urmia Lake and the Moses Bay wetlands have had the most decrease and increase rates, equal to 109.02 and 4.82. The reduction rates often are related to the inland or the northern coastal wetlandsBased on the results, surface water loss in wetlands has been concurrent with a significant decrease in TWS and the average input discharge of wetlands. In additionthe highest percentage of moderate to severe eutrophication occurrence is recorded in the west of the Urmia Lake, Payab Etrak, and Ajigol subbasins, which accordingly are 97.43, 37.91, and 16. Nayband Bay and Steel -e- Abbas Abad are wetlands with the highest occurrence of normal and severe eutrophication conditions. Generally, wetlands with the highest eutrophic and hyper-eutrophic water occurrence percentages are mostly located in inland and northern coastal wetlands. The maximum oligotrophic and mesotrophic water occurrence percentages usually are reported in southern coastal wetlands
  9. Keywords:
  10. Wetland ; Remote Sensing ; Machine Learning ; Eutrophication ; Iran ; Environmental Monitoring

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