Broken-Line Model of Dam Storage and Evaluation of Water Supply Safety Using a Bivariate Frequency Analysis

Abstract

In this study, a new evaluation method for the water supply safety of a dam is proposed. This method considers both climatic conditions and storage characteristics of a dam. The annual variation of dam storage is represented by a broken-line model, the lines of which are determined by only three factors: the monthly design water supply during the dry period; dam storage at the end of the dry period; and changes in dam storage during the wet period. From the results of bivariate frequency analysis, a unique broken-line model is derived under multiple scenarios with the given return periods for the evaluation of water supply. The proposed method is applied to a total of five major dams in Korea. It is shown that the water supply safety of a dam can be quantified by using the concept of the return period, and five major dams have water supply safety corresponding to return periods of 10–50 years. Among them, the Soyanggang Dam is found to be the most stable with respect to water supply safety in Korea.