Hydrological analysis of bed stability in the Masiel Mouchan River- Markazi Province

The river is a dynamic phenomenon that is constantly changing. Estimating the resistance of sediment particles against erosion will identify stable and unstable points in different areas of the bed. Study area of this research was of Masiel Mouchan River in the Astaneh city. In this study, we investigated threshold of (transformation and deposition of bed sediments, in 4 cross sections. the critical shear stresses and the critical unit discharge calculated for four particle sizes D16, D50, D84 and D95 in all sections, and results shows, sediments in D16, D50, D84 and D95 diameter moves at bankfull discharge in sections 2 and 4, therefore sedimentary conditions of the river bed will change at bankfull discharge. At cross sections 1 and 3, particles with a diameter of D84, D95 will remain stable in bed, and other particles smaller than this size was unstable. Sediment particle are unstable in cross section of 2 and 4, because Slope of cross sections 2 and 4 are greater than 1 and 3 cross section. Finally, the results of both methods (critical shear stresses and the critical unit discharge) have high confection and confirms these methods are useful for stabilization studies in other rivers.