Evaluation of Bed Load Discharge Formulas in Alpine Gravel Bed Rivers (Case study: Chehel Chai river in Golestan province)

Determining the exact value of bed load is concerned with investigators. In this study the performance of 13 bed load sediment transport formula developed for use in steep gravel-bedded armored ChehelChay River, Iran is tested. The formulas are applied in the manner intended by the original authors. The results have been expressed in terms of a discrepancy ratio (r) defined as the ratio of the predicted and measured transport rate. The method of Ackers and White yields the best results for field data with 64% of the predicted transport rates in the range of 0.5≤ r ≤2. The Meyer-Peter and Mueller and Van Rijn equations yields approximately good results with 43%, and 36% of the predicted transport rates within a factor 2 of the measured values, respectively.