determination of the most suitable method for estimation of suspended sediment in hydrometric stations upland of latian and taleghan dams

there is a lack of accurate and correct information about erosion in iran. moreover, there is a big difference between measurements and estimations. sediment is also an important environmental problem which pollutes water physically and chemically and therefore, sediment problem is usually studied as environmental problems. estimation of sediment yield of drainage basins is important for prevention of sedimentation. in this research, by optimization of sediment rating curves in bagh-tangeh, narvan and afgeh hydrometric stations in latian drainage basin and gelinak hydrometric station in taleghan drainage basin, an optimized method for estimations of suspended sediment yield is proposed. six methods of linear, multi-linear, median of classes, fao correction coefficient, parametric and non-parametric correction coefficients were used. by using daily flow discharges, suspended sediment yield was estimated. to select best model, mean percentage of relative error, efficiency coefficient and determination coefficient were employed. the results showed that sediment rating curve using the median of classes has the lowest mean percentage of relative error and the highest efficiency coefficient and determination coefficient. it has also the highest potential prediction. the result also shows that more than 70% of yearly sediment yield has been transported during flood-period months of march, april and may, which comprise less than 25% of the period, indicating the importance of condense sampling during these times.