Development of an ecological impact assessment model for dam construction

The purpose of this study was to develop a model for assessing the ecological value of a dam reservoir. Various evaluable characteristics ("elements") that influence the ecology of the target area around the dam were grouped into three classes: (1) physical elements, such as altitude, slope, and aspect; (2) vegetation elements, such as forest physiognomy, vegetation type, age class, diameter at breast height (DBH) class, and density; and (3) habitat elements, such as ecological conditions, vegetation conservation classification, and frequency of wildlife appearances. The evaluation standard was quantified considering the ecological function of each element. The developed assessment model was applied to the Yeongju Dam in the Nakdong River basin in Korea. This study assumed that the ecological condition before the dam construction was 100 %. The results of this study showed that the physical, vegetation, and habitat elements were downgraded to 82.8, 95.5, and 90.7 %, respectively, after the construction of the dam. The overall ecological value was estimated to be 90.0 % and thus decreased by 10.0 % due to dam construction. Additionally, by combining the results for the evaluation elements, an ecologically healthy area was selected. The results of this study should prove useful for quantifying ecological impact and for establishing an ecological restoration plan for dam reservoirs.