Effects of Geomorphology of Alluvial Fans on the Physical and Chemical Changes of the soil of Alluvial Fan in the Southeast of Shah Gheib’s Salt Dome, Larestan

Alluvial fans are ideal places for investigating the effects of geomorphological processes and landforms on soil properties. This study aimed to investigate the effects of geomorphological forms and processes on physical and chemical properties of soil in an alluvial fan located in the southeast of Shah Ghaib salt diaper. The study area alluvial fan is composed of three surfaces including very old, old and young. The phosphorous, potassium, absorbable sodium, calcium carbonate, saturation moisture of soil, water’s holding capacity in soil, soil texture, and organic carbon parameters were measured in 72 soil samples on the alluvial fan surfaces.The results showed that the sodium, potassium, EC, calcium carbonate, phosphorous, and holding capacity of water, silt, and clay parameters were higher in the interfluves than the channels in inactive (very old and old) surfaces. The organic carbon, pH, saturation moisture of soil and percentage of sand is higher in the channels. Also, the sodium, potassium, EC were more in the young compared to the old and very old surfaces. The PH, phosphorous, and saturation moisture of soil were higher in the old surface than in the young and very old ones. The amount of calcium carbonate, water’s holding capacity in soil and percentage of silt were highest in the very old fan surface. The correlation coefficient between the measured parameters of the soil indicated that there are strong positive relationships between the clay and the sodium, electrical conductivity, calcium carbonate, and potassium. In general, the results show that geomorphological processes such as entrenchment in channels and weathering on the surface of the interfluves have controlled on the values of the physicochemical parameters of the soil in the study area alluvial fan.