Assessment of formations erodibility through reagent alluvial sediments morphoscopy (Case study: Sajjadrud basin)

Erodibility of basin formations is depends on their resistance versus of erosion. In a basin are not the same stones, their resistance and covering area. Obviously, formations sensitivity versus of erosion are determining rate of sediment production in a river. In this research has been analysis formation erodibility versus of erosion in the Sajjadrud basin. Research methods are descriptive–analytical and based on field and library methods. In order to determination of formation sensitivity versus of erosion, initially from downstream and around output of basin, were taken 20 samples with selected-randomly method. The samples after of preparing in the laboratory with morphoscopic and morphometric methods based on kind of stone have been separated to seven main groups. Then basin was delimited using of digital topographical map with scale of 1: 50000 and geological map with scale of 1: 100000 and also Landsat satellite image, then covering extent by each formation has been identified and survey. In the next stage separated samples of sediments has been adapted with maps. In this regard, according to adaptation homogeneous area, has been determined erodibility of stones each any group and area. Then has been transferred extent any area on the map with Arc GIS software. Results shows that erodibility in formation that their kind is limestone and sandstone, have maximum amount and shows volume of degradation in the basin. Lar and Shemshak formations have the largest percentage of limestone and sandstone therefore are the most erodibility formations in the basin. Also, shale and silt stone, respectively have less erodibility in the basin.