Study on the Measures for Removing Water Intake Problems for Pumping

In many dam regulating reservoirs in Japan, sediment accumulates year by year, resulting in continued payment of dredging costs. Therefore, efficient sediment disposal and sediment inflow control are currently being examined, even in HEPCO's dam regulating reservoirs. To achieve more efficient operation of the pumped storage power station, it is necessary to remove problems in water intake for pumping due to sediment disposal.

In this study, we propose more efficient operation aimed at easing regulations on the pumping operation, and method for reducing sediment disposal costs. Accordingly, in order to comprehend sand accretion and flow duration around the outlet (intake for pumping) of our pumped storage power station, we performs (1) analysis of the current state, (2) hydraulic model experiment and (3) numerical analysis.

Photo-1 Hydraulic model experiment equipment
(the outlet of the pumped storage power station)

After the investigation around the outlet of the pumped storage power station, the following findings were obtained.

1. (1) The hydraulic model experiment found a detailed mechanism of accumulation of sediment that comes out of a nearby tributary.

2. (2)The field survey demonstrated the movement of sediment in the regulating reservoir.

3. (3)The hydraulic model experiment and two-dimensional flow analysis showed flow duration in the regulating reservoir after the water meets with the nearby tributary.