Study on Planning of a Small Hydropower Development under Consideration with the Basin Environment

Abstract

We investigated planning of a small hydropower for development of local community depending on natural resource which conserves natural landscape and basin ecosystem in the Ochiai River, a tributary of the Yoshii River in Okayama Prefecture. Field surveys were conducted for flow volume measurement at six sites in the basin to predict hydropower potential. At a same time, we surveyed also on geomorphological and physico-chemical environmental factors (micro habitat composition, water quality parameters, canopy openness, etc.), aquatic animal communities and water fall landscapes in the basin. The benthos and fish fauna of the Ochiai River was characterized by a set of endangered species, such as Nagare-hotoke-loach (Onychodactylus japonicus) and Japanese clawed salamander (Onychodactylus japonicus) in the upper reaches, indicating the environmental conditions of their habitats should be conserved in a high priority. In addition the EPT and ASPT indices of benthic communities and the waterfall images taken by the interval cameras were used for environmental assessment of a dam impact. . Based on the results, we proposed the suitable site location of small hydropower in term of both of higher energy gain and nature conservation including habitats of endangered species. We investigated these location in eight cases according with environmental flow pattern considering with aquatic animals, waterfall landscapes in tourism seasons and tributary inflow below the water intake site. The planning procedure shown in this study will benefit local villages in general by sustainable energy of small hydropower generation and by rediscovery of ecosystem services and life styles utilizing original natural resources in the basin.