Abstract

In the Kurobe River, coordinated sediment flushing operations of Dashidaira and Unazuki dams have been executed since 2001. From the viewpoint of the comprehensive sediment management in a sediment routing system, monitoring of quantity and quality of sediment transport during these flushing events in rivers and reservoirs is very important. This paper shows results of the field data obtained during the flushing and the sluicing operations of Unazuki dam in 2005. Suspended sediment concentration (SS) measured by the manual sampling and SMDP (Suspended Sediment Concentration Measuring System with Differential Pressure Transmitter), turbidity measured by a turbidimeter for high sediment concentrations and grain size distribution are discussed. Based on these data, movement of the suspended load discharged from Unazuki dam during flood, flushing and sluicing periods is clarified. Difference between the turbidity and the SS values is also discussed from the viewpoint of the sediment grain size distribution.

Keywords: reservoir sedimentation, sediment flushing, suspended sediment concentration, SMDP