Writers : Kharghani, A.R; Torshizian, H. A.; Moussavi, M. J.; Javanbakht, M.; Sharifi, E.
Refference : The first international applied geological congress; Department of geology Islamic azad university- Mashhad
Publishing Year : 2010

Abstract :

Frizis river drainage-basin is located in northwest of Mashhad with a surface area of about 333.7 km2.This drainage basin flows from south top branch of Kashafrood River. It is located in Mashhad-Chenaran plain and its source is in Binalood mountains.
The above- mentioned river is mainly gravelly in the study area with a bed load and single channel and consequent stream types. In many gravel –bed rivers, the grain size changes exponential toward downstream and is mainly related to selective deposition of material on the streambed according to size, distance of transportation, erosion, vertical and lateral sorting. However, most studies on the cause of downstream fining in the rivers emphasize hydraulic sorting as the dominant fining mechanism. Sediments grain size variations and causes for fining downwards were studied at 27 sites.
In general, sediments are poorly sorted, positively skewed and mainly platys to mesokuritic. In Frizi river drainage-basin, the rapid reduction of slope is one of the main geomorphologic factors that cause fining toward downstream. Another main factor in downstream fining of grain size is selective transport due to changing hydraulic condition which is controlled by hydrology of drainage basin as well as catchments slope.

Subject List : Fining trend , watershed