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Relationship between Dust Outbreaks and Soil Moisture in the Urmia Lake Periphery

Faturechi, Mohammad Hadi | 2019

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 52100 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Tajrishi, Masoud
  7. Abstract:
  8. Desiccation of different salty lakes around the world has been considered as one of the most critical environmental events. Gradual desiccation of the Lake Urmia and retreatment of its shoreline with respect to ecological level (1274.1 meters) have resulted in new hotspots for dust outbreaks, especially in east and south-east peripheries, which were previously under water. These areas, part of which are salty, are now exposed to open air and susceptible to wind-erosion. Soil moisture, as one of the most important parameters for dust prevention, determines the threshold friction wind speed over playa because it increases the cohesion between soil particles. Therefore, compared with dry soil, soil with low moisture requires faster wind speed (threshold value) for the start of a dust and salt outbreak. In this study, in addition to wind speed and visibility data obtained from meteorological synoptic stations, remote sensing Aerosol Optical Depth (AOD) has been employed for dust detection. In addition, soil moisture has been evaluated using soil moisture retrieval algorithms in visible and microwave regions of electromagnetic spectra. The purpose of this study is to determine the relationship between dust outbreaks and soil moisture of the desiccated lakebed in the peripheries and lakebed areas of the Lake Urmia. The results show that in the visible and microwave regions, if soil moisture is, respectively, lower than threshold values of 0.065 and 16%, the lowest wind speed could result in a dust outbreak. Moreover, local dust has been observed in days in which soil moisture in the east, south, and west peripheries were respectively 31%, 20%, and 39% lower than the average soil moisture between 2008-2013. Finally, it was shown that the east and south-east peripheries and lakebeds have lower soil moisture than other areas and play a more important role in dust generation
  9. Keywords:
  10. Dust Outbreaks ; Soil Moisture ; Remote Sensing ; Aerosol Optical Depth ; Wind Speed Forecasting ; Urumieh Lake

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