Estimating the Suspended Sediment Load and Evaluating the Homogeneity and Heterogeneity of Water and Sediment (Case Study: Kasilian watershed, Mazandaran)

There is a significant difference between the observed and simulated suspended sediment yield with respect to many watersheds in Iran as this country does not have sediment stations. Due to station limitation, it is necessary to evaluate the experimental models and statistical methods for estimating the transfer rivers suspended sediment. The aim of this study is to evaluate homogeneity and heterogeneity, the trend of changes in discharge and sediment value and assesses a suitable comparison of suspended sediment load estimation methods efficiency using rating curves. The present study, the ProUCL software was used through the Kendall and Pitt test to evaluate trend changes and homogeneity and heterogeneity of time series relating to water and sediment discharge, respectively. To estimate suspended sediment a one-line, two-line, and mean-load rating curves were used. The performance of the methods was evaluated based on R2, NSE, RMSE and SD and the best method was selected. The finding of this study suggested that the mean-load method was selected as an appropriate method with the highest efficiency in the study area. Further, the trend changes of water and sediment discharges using the Kendall test showed that the trend is declining with a significance level of 5% and indicated that there are adaptations between water and sediment discharge changes. Pittet test revealed that the discrete time series in related to water and sediment discharges are homogeneous and heterogeneous, respectively. Therefore, having knowledge about the homogeneity and heterogeneity of water and sediment discharge can be effective in protection measures and environmental effects moderation.