Accumulation of Sediments in a Reservoir and Its Countermeasures "A Case Study of SAKUMA Dam".

Abstract

Countermeasures to decrease sediment accumulation in reservoirs are important to keep functions of reservoirs. Also in recent times an idea of unified management of sediments from mountains to the sea is increasingly promoted. On the other hand, more effective utilization of sediments for such as concrete aggregates has to be taken into account as natural resources have become scarcer.Here we report accumulation of sediments in the reservoir in Central Japan as an example, and discuss mechanism of sediment accumulation based on many drilling and grain size distribution data.Much sediment accumulations among mountainous areas often result in problems in functions as reservoirs and in environmental deteriorations. Formation of sediment, grain-size distributions, and sediment accumulation rates are all closely related to water level manipulation and amount of flow at flood times.In the future, for SAKUMA dam reservoir, more serious thought of unified sediments and erosion control from mountains to the sea should carefully be examined including removal of more sediments from the reservoir, efficient use of finer materials, and returning sediments to the rivers.