Investigation of Turbulence in Micro-landforms of Meyghan Playa Using the Fractal Method

Drying of fine sediments and clay in the environment of a playa causes shrinkage stress and the formation of cracks and polygons followed by the formation of the mud polygons. Many factors such as moisture content, temperature, type of clay minerals, topography, salinity, and biotic disturbance affect the distribution and evolution of these multifaceted morphometries. Therefore, the study of the fractal properties of these forms can shed light on the process of their change in response to environmental conditions. The present study was conducted to investigate the pattern of micro-landforms in the western part of Meyghan playa. Based on this, about 300 clay polygons were photographed in June 2018 through field observations to apply the geo-Fractal model. Then, using the AutoCAD software, the perimeter and the area of each microform were accurately measured, and the fractal dimensions of the perimeter and the area as well as the DAP values were calculated by the Excel software. Based on the results, clay polygon patterns showed three classes of moderate, high and very high chaos with the DAP values of 1.73, 1.91 and 2.8 respectively. Therefore, it can be argued that, on the one hand, short-term developments have caused the disturbance of muddy polygons in the region. On the other hand, the intensity of changes in the perimeters of these shapes, which is probably due to the reduced moisture content, increased sediment concentration, salt accumulation on the edges, and margin uplift, was more than the intensity of change in their area. Such a phenomenon reflects the infinite geometry of the fractal dimensions of clay polygonal perimeter in Meyghan playa.