Document Type : Research Paper


1 M.s. Student of Sedimentology, Islamic Azad University, Science and Researches Branch, Tehran, I.R.IAN

2 Professor, Reclamation of Arid and Mountainous Areas, Faculty of Natural Resources, University of Tehran, I.R.IRAN

3 Associate Professor, Soil Conservation and Watershed Research Center, I.R.IRAN


More accurate understanding of rock formations and sedimentary units sensitive to erosion will
enable us to present appropriate and timely methods in order to prevent accelerated erosion. In this
study, through predefined sampling from main and minor channels and granulometric analysis
using index sieves, mineralogical investigation has been performed qualitatively and quantitatively
by binoculars in laboratory. After that, sedimentation potential has been calculated by using
practical formulas. Then, sedimentation potential of each sedimentary unit has been estimated from
average results of sedimentary sample and with this method, sedimentation potential of Shafarood
Watershed has been obtained from average results of five sub basins. An equation has been
calculated for each sub basin and by this, an equation for whole watershed was presented. In this
equation, the Y which refers to the amount of delivered sediments has been placed in one side and
rock unit coefficients on the other side. The coefficient of each rock unit has a rule in sediment
production. These coefficients are dimensionless and demonstrate rock unit sensitivity to erosion.
The bigger this value, the more sensitive that rock unit is to erosion. In this way, the map of
sensitivity to erosion for each sub basin has been prepared by using (ARC GIS) software.
According to average sedimentation potential of Shafarood Watershed, marl units (Pgf), silty sandy
shale (Jsh) and sandy limestone (Kusl), have respectively the highest sensitivity and limestone units
(P), andesite - basalt (Pev) and tuffy shale (V) have the least sensitivity to the erosion.