A proposal for enhancement of hydro power potential by utilyzing the storage of rain water in unsaturated soil

In this paper, a technique to enhance the hydropower potential by increasing the base flow of the rivers along which hydro power station(s) is/are constructed is proposed. First, the real situation at present time of the energy gain by hydropower stations is examined using the data of annual report and the possibility or actuality of enhancement of hydropower is discussed. It has been shown that the total capacity of the existing hydro power facilities in Japan is about 47 million kW while the actually generated is only about 10 million kW in average, which implies the necessity to increase the base flow of the river. Then, the technique to increase the base flow utilizing the seepage of rain water into the soil before flowing into the rivers is discussed. The key point of this technique is the upward seepage in unsaturated soil without losing the permeability. The preferable sites are discussed from the viewpoint of the stability of the ground. Finally, a rough estimate is given for the increase of the base river flow.