Utilizing inactive storage in a dam reservoir during extreme drought periods

Abstract

The purpose of this study is to suggest a structural plan for improving the utilization of inactive storage in dam reservoirs, to mitigate extreme drought. Inactive storage in the dam is composed of emergency storage and dead storage. The emergency storage can be used in emergencies such as drought. But, in general, the dead storage for sedimentation is not used, even in an emergency. Therefore, we developed a methodology to determine how the dead storage space can be partially used during extreme drought periods when the sedimentation has not occurred yet. We call this partial space in a dam reservoir “drought storage”. An accurate analysis of sediment levels needs to be performed before calculating drought storage, and so the present sediment level in the dam reservoir was estimated using SED-2D linked with the RMA-2 model of SMS. After considering the additional available storage capacity based on the estimated sediment level, drought storage was finally determined. We also predicted future sediment levels after 100 years and suggest the amount of drought storage available in the future. As a result, we found that the available drought storage will be lower in the future compared to present drought storage, due to the gradual increase in reservoir sedimentation over time in the dam. Further research may be needed to effectively reduce sedimentation in order to increase the drought storage capacity.