ESTIMATING THE BED LOAD TO SUSPENDED LOAD RATIO IN CENTRAL ALBORZ RIVERS; IRAN (CASE STUDY: TALEGHAN AND JAJROUD RIVERS)

Difficulty in measuring bed load, lack of appropriate technology, and indistinct boundary between bed load and suspended load induce experts to determine a part of suspended load as bed load. This ratio in many rivers with different conditions has the same coefficient and sometimes in a river, different experts estimate different ratios. In this study, two reach of Taleghan and Jajroud rivers was selected to determine this ratio and streamflow was simulated by HEC-RAS software in both reaches. Bed load was calculated by Meyer-Peter-Muller, Casey, Schoklitch and VanRijn equations, and Einstein, Chang-Simons-Richardsin, Begnold and Toffalati equations were used to estimate suspended load. Results showed that in both rivers, Schoklitch equation provides the best estimation for bed load. Also for suspended load, Einstein and Begnold equations provide the best estimation for Jajroud and Taleghan rivers, respectively. The bed load to suspended load ratio was estimated 376% and 14% in Jajroud and Taleghan rivers, respectively.

Bed load, HEC-RAS, Jajroud River, Suspended load, Taleghan River