Investigation morphology and sand dunes activity in different parts based on Lancaster index (Case stydy: Kashan Erg)

Kashan Erg is one of the most important sand dunes complexes in Iran. Due to erosive winds, always, Erg's marginal areas are faced to the transition of moving sands. So, in this research, the sand dune activity was investigated by Lancaster index. In this line, Erg's morphology map was prepared using aerial photographic, Google earth software and field observations. Then, maps of isohyet, potential iso-evapotranspiration and percentage of higher velocities than threshold wind velocity in 10 meters above ground level were prepared using the analysis of anemometer data obtained from adjacent stations of Erg and their integration in GIS software. Finally, the Erg activity map was drawn. According to the Lancaster index, threshold wind velocity was considered equal to 12 knots. The results showed that in most of Kashan Erg areas, sand dunes are active and only in small areas in north and south of Erg, they are very active.