Semi-Detailed Mapping of the Playa Surfaces in the West of Lake Urmia and their Contribution to Aerosols

The recession of the lake shores, including Lake Urmia (LU), and later exposure of the lake bed sediments to wind erosion, as a consequence of climate change and drought is an increasingly dangerous phenomenon in arid and semi-arid regions of the world. When salt particles remain unconsolidated, and uncovered on soil surface, they can be moved by wind easily, generating salt dust. These fine-grained salt particles cause salinization of agricultural lands, accelerate deforestation leading to health, and economic problems in lives neighboring residents.  The aims of the present research were to study Urmia Lake Playa (ULP) geomorphic surfaces in its western shores, and their vulnerability to dust generation. All lands from Urmia Lake recession from its western shores were selected. Different playa surfaces in the study area were identified and mapped using satellite images and Google Earth software. Then, boundaries of the mapped surfaces were checked by field observations. Later 130 soil samples from depth 0-5 cm of different surfaces were collected during spring to autumn 2019 and physicochemical analysis, mean weight diameter (MWD) and loose erodible material (LEM) were determined and finally geomorphic map of the study area was prepared in ARCGIS software. Based on the results from present study, seven geomorphic surfaces were identified in western part of ULP including clay flats, salt crusts, clay flats- salt crusts; sandy salt crusts, beach sands, sand sheets and fan delta. Each of these surfaces were subdivided to different map units based on the variation in vegetation cover and density, stability of surficial crusts and some other physicochemical properties. Among studied surfaces, sand sheets located in northern parts of the study area, next to Jabal Kandi village, had the highest LEM with 89.7 % equal to 53.8 ton.ha- soil. The study of the correlation between LEM and several soil physicochemical properties showed that high sand content and low calcium carbonate, MWD (which is also dependent of soil properties) and also low organic matter in soils of sand sheets have made these areas vulnerable to wind erosion and prone to dust generation.