Assessment of the effect of classification on the improved estimation of suspended sediment load using hydrological methods (Case study: Taleghan Basin)

One of the important issues in design of river structures as well as determination of proper life time is having adequate information of sediment load in the rivers. Thus, several methods have been suggested for estimation of suspended loads. One of the hydrological techniques is rating curves method that is based on the best fitting line to drawing between values of flow discharge and suspended loads respectively. Seasonal variability is one of the errors which origins in sediment rating curves that disregarded to accurate estimation of suspended load. In this research seasonal classification, by analyzing annuals hydrograph on the sampling time with 6 hydrological methods in 3 different seasons for estimated suspended loads and the best fitting method and season was determined in Glinak hydrometric station of Taleghan Basin. The results showed that the quality of primary data is the most important parameter in accuracy and precision of the estimations. However classified total data have considerable affect on decreasing error estimate and also due to the increasing precision (decreases MAE) and accuracy (StDev decreasing) estimates 6 and 77.8%, respectively. Finally, the best determination methods for estimating process in the research which are suitable for total data, two rating curves and FAO methods for rainy season data, CF2 method for flood season data classes, one rating curve method for dry season class and FAO method. Also, discharge-sediment load data from flooding season are the best seasonal classes among the methods in case of minimum error.