Investigating the relation between sediments texture and gullies development in plains in the southern part of eastern Alborz using statistical analysis method (Case study: Garmsar-Seyyed Abad)

Surface sediment's particles diameter is closely related to dominant processes of developing surface morphology of landforms. This study investigates the relation between sediments texture and gullies development in southern plains of eastern Alborz using statistical analysis and measuring the particles' diameter in four pilots in Garmsar-Seyyed Abad, Iran. The pilot sites were selected based on differences and similarities of surface morphology using satellite imageries and field studies. Samples were collected from bottom, middle, and upper part of gullies. After measuring the weight and doing sieve analysis of representative samples, the results were analyzed using GRADISTAT software in the form of graphs and tables. In addition the morphometric index was measured collecting 800 samples from 5*5 m boxes. The results showed that the surface sediments are derived from multiple sources which indicates the difference of effective processes over time (sites 1, 2 and 4, covered by gravel pavement called sandy gravel, sited 3 covered by gravely sand. Site 1 and 4 are derived from two sources, site 2 is three sources, and site 3 is single source). Poorly sorted sediments indicate that the size and type of gully's surface and deep sediments have not been able to fully affect on gullies development in all sites. Therefore, gullies development is not only related to sediments texture and diameter, but also consideration of more important factors such as tectonics processes is required in these sites.