Geomorphic surfaces of eastern lake Urmia Playa and their influence on dust storms

Abstract

Lake Urmia is one of the most important salt lakes in the world and the largest in Iran. At present, because of the recession of Lake Urmia and deposition of lacustrine sediments on the lake bed, a large part of the surrounding areas has become flat with several playa surfaces. So far, there have been very few studies related to Lake Urmia playa and its geomorphology. Therefore, the aim of this research was to field study of playa surfaces of Lake Urmia in its eastern part and also to identify areas susceptible to wind erosion. In this study, different playa surfaces from the northeast to the south of the lake were identified and mapped using satellite imagery. Then, boundaries of the mapped surfaces were checked during field observations. Moreover, physical soil properties, such as texture, bulk density, saturation percentage, resistancy, particle size distribution and soil aggregate stability, were determined. Next, the correlation of the studied properties with each surface resistance to wind erosion was investigated, and finally the geomorphic surfaces of Urmia Playa and their resistance to wind erosion were mapped using ARCGIS software. Based on the results, the study area included agricultural lands, shrub-grass zones, sand and gravel zones, mud-clay salt flats, sand-salt crusts, puffy grounds, delta-fans and wet zones. Results showed that approximately 25% of the surfaces had high resistance to wind erosion and they are therefore stable surfaces with no potential for generating dust in the future. About 35% of the surfaces were strongly susceptible to wind erosion, highly prone to generate saline dusts and sand storms. These areas were located in the east and southeast of the lake. Also, 40% of playa surfaces had moderate resistance to wind erosion. These areas can become very sensitive to wind erosion if ground water depth or the roughness of the surface changes. In conclusion, sandy-salt surfaces in the east and southeast of the lake are the most susceptible to wind erosion with high potential for generating dust, sand, and salt storms, which can affect agricultural lands and human health in the near future.

Keywords: dust, erosion, geomorphology, Inceptisols, playa, Lake Urmia