Characteristics of Sediment Transport Along the Yom River, Thailand

The sediment transport characteristics of the Yom River have been crucial necessary for planning, designing, and operating water resources development projects in the Yom River Basin. They have also been essential for evaluating the sediment discharge of this river to the Chao Phraya River, which is the largest river in Thailand. The objectives of this study were to examine the characteristics of sediment transport in the Yom River and to study the proper sediment transport functions for predicting the total sediment transport rate for the Yom River Basin. River survey data observed in 2011, 2012, 2013, and 2018 including river cross-section, river flow, suspended concentration, bed load, and bed material, were used for studying them. The eight sediment transport functions in HEC-RAS software, namely Ackers-White, Engelund-Hansen, Laursen (Copeland), Meyer Peter Muller (MPM), Toffaleti, MPM-Toffaleti, Yang, and Wilcock-Crowe, were tested in order to select the optimize sediment transport function by the Root Mean Square Error (RMSE) test. The results showed that the total sediment loads along the Yom River was mainly in suspension, as well as the bed-to-suspended sediment load ratio varied from less than 0 to 1%. The maximum bed load transport occurred in the mountainous reach of the Yom River. It also revealed that the bed material samples of the river were from medium sand to very fine gravel, with the median diameter (d₅₀) ranged between 0.29 and 2.73 mm. In addition, the Laursen (Copeland) function was the best of 8 functions in HEC-RAS software for estimating the total sediment transport rate of the Yom River.