A Risk Analysis by the Ratio of Basin Area to Capacity Based on the Reservoir Failures in South Korea

There are about 17,000 reservoirs in South Korea and the reservoir failures repeat almost every year. Although many factors influence the failures, we focus on the effects of the ratio of basin area to capacity (B/C ratio) in this study. Especially, the effect of the B/C ratio looks more remarkable in small and medium-sized reservoirs which do not have sluice gates to control floods. First of all, we build up the database of reservoir failures in South Korea for a statistical analysis of the risks with B/C ratio. A total of 170 failures were collected from the multiple sources such as request of information disclosure, literature review and media report search. We failed to find out the specifications of 33 failures as they were abolished due to breach of reservoirs. All small and medium-sized reservoirs in South Korea were assigned into five categories by the B/C ratio, and the failure frequencies were analyzed in each category. The results showed a qualitative trend that the categories with a larger B/C ratio had a higher frequency, but the limitation was found in a quantitative analysis of risk sensitivity.