IMPACTS OF DAM-INDUCED HYDROLOGIC ALTERATION ON RIVERINE ECOSYSTEM IN THE MIMI RIVER

Abstract

 Dam reservoirs are well known to greatly alter the downstream environments. However, few studies have explored effects of dam-induced flow alterations on stream ecosystems to date. Here this study investigated a river that harbors multiple hydropower dams to understand the impacts of hydrologic alteration on stream organisms (fishes, invertebrates, algae). We computed the Indicators of Hydrologic Alteration using the dam outflow discharge data and performed the principal component analysis. As a result, the first principal component was explained by extent of discharge and variation in flow regime (= 56.2%), and clearly distinguished the studied sites in the fully regulated river sections from the moderately regulated site. The first principal component displayed significant (P < 0.05) negative correlation with the fish individual number (r = -0.502), and positive correlation with the fish species diversity (r = 0.706). Hence, it is suggested that the partial riverine organisms may be affected by different extent of flow alteration by the hydropower dams.