IMPACT ASSESSMENT OF WETLAND RESTORATION WITH VEGETATION MANAGEMENT IN WATERSHED ON SMALL HYDROPOWER DEVELOPMENT POTENTIAL

Abstract

 A nature restoration of the Kuroiwa Moor has been conducted for compensation of environmental impacts on recession area of a small hydropower plant in the Ochiai River in northeast part of Okayama Prefecture. In order to evaluate the effects on the hydropower efficiency, we estimated the flow duration curves under different conditions of vegetation patterns in the watershed. One of the causes of wetland degradation in the Kuroiwa Moor is decreases of the wetland water level induced by forestation and increase of evapotranspiration in the watershed. Then we focused on the historical vegetation change and built a tank model with incorporating evapotranspiration and canopy interception effects. Using the model we evaluated Hydropower Development Potential which has an influence on hydropower generation. As a result, Hydropower Development Potential under the vegetation distribution of 1948 is the highest among those of 1948, 1976 and 2017. The results of this study can be applied as a model of small hydropower development in quasi-national parks.