Tracing the source of difficult to settle fine particles which cause turbidity in the Hitotsuse reservoir, Japan

A unique method to trace the source of “difficult-to-settle fine particles,” which are a causative factor of long-term turbidity in reservoirs was developed. This method is characterized by cluster analysis of XRD (X-ray diffraction) data and homology comparison of major component compositions between “difficult-to-settle fine particles” contained in landslide soil samples taken from the upstream of a dam, and suspended “long-term turbid water particles” in the reservoir, which is subject to long-term turbidity. The experiment carried out to validate the proposed method, demonstrated a high possibility of being able to make an almost identical match between “difficult-to-settle fine particles” taken from landslide soils at specific locations and “long-term turbid water particles” taken from a reservoir. This method has the potential to determine substances causing long-term turbidity and the locations of soils from which those substances came. Appropriate countermeasures can then be taken at those specific locations.

► Properties of soil particles and turbid water particles in dam were specified. ► Homology was evaluated by comparing soil particles with turbid water particles. ► Cluster analysis of XRD and component compositions were used for homology evaluation. ► The proposed method enables source soils causing turbidity in dams to be located.