Assessment corrective methods for estimating suspended sediment (Case Study: Beshaar Watershed)

Regression equations of sediment rating curves are too biased due to the logarithmic of the discharge and suspended sediment data. In this study, correction coefficients were used to improve the results of river sediment estimation methods in Bashar and Zohreh hydrometric stations with different indices of accuracy and precision. The present study aims to evaluate the performance of five methods of rating curve including FAO, MVUE, QMLE, LRC, Ls in the case of intermediate categories and no category situations. Root mean square of error and coefficient of efficiency indicators were used to evaluate the performance of sediment rating curves and to choose the best of them. Results of root mean square of error and coefficient of efficiency indicators computation indicates that in the Bashar station LQMLE method is provided maximum coefficient of efficiency (CE=92) and the minimum error (RMSE=0.38) and LS method had the lowest coefficient of efficiency and highest error (CE=86 and RMSE=0.94). In normal state the same results has been obtained. Zohreh station correction coefficients results showed that the maximum coefficient of efficiency is related to LQMLE (CE=95) and FAO had lowest coefficient of efficiency and the highest root mean square of error (CE= -1.58 and RMSE=2.48). In normally condition the LRC method has achieved maximum coefficient of efficiency and minimum error (CE=95) and (RMSE=0.53). On the other hand, amongst the different methods, LS is provided the lowest coefficient of efficiency and the highest root mean square of error (CE=-7 and RMSE=3.88). In general, by application of different methods and different correction coefficients of sediment rating curves in cases of non-classified data and the intermediate state, concluded that in most models the LQMLE and LRC is the best method of calculating sediment.