A case study: bivariate drought identification on the Andong dam, South Korea

摘要

Identifying hydrological drought in reservoirs is a significant challenge in water resource management. In South Korea, drought in reservoirs has historically been identified and managed through measuring storage amount. However, drought identification in accordance with storage amount has a possibility of failure to secure enough time for proper drought countermeasures. This study aims to suggest supplementary criteria for quantitatively identifying drought based on storage amount and water balance-specifically to allow more time to implement countermeasures against drought on the Andong dam. The standardized balanced index (SBI) was newly suggested to consider dry/wet conditions of dam, and the Standardized storage volume index (SSVI) was employed to consider storage amount. The proper duration of each index was estimated to be 4-month for SBI and 9-month for SSVI. A bivariate drought identification diagram using both index and copula function was derived and applied to the Andong dam. The diagram identified drought to occur 3.7 months earlier than the existing criteria which used storage amount to identify drought, and showed applicability for supplementary criteria.