Dam Renovation to Prolong Reservoir Life and Mitigate Dam Impacts

Dams are essential to society, yet have tremendous environmental impacts, for which there is an increasing interest in mitigation. At the same time, sedimentation threatens the sustainability of reservoir storage and reservoir functions. We use the term dam renovation to encompass a wide range of measures, including dam rehabilitation, a term commonly used for structural retrofits, typically of the dam structure or spillway, fishway retrofits for migratory fish passage, reservoir reoperation, which involves modifying dam operations to improve flow regimes for ecological purposes, and sustainable sediment management, which includes measures to pass sediment through or around dams, as well as other mechanical measures to restore sediment connectivity. Compared to dam renovation, an inordinate amount of literature has been published on the topic of dam removal. While in some cases dam removal is a practical way to improve river condition and to resolve the safety problems of aging dams, the reality is that most dams in existence today will remain for the foreseeable future, provided they do not fill with sediment, or their structures deteriorate to the point of failure. Thus, it is imperative that we understand the options available to renovate dams with poor environmental performance or whose sustainability is threatened

Assessment of Activating Reservoir Emergency Storage in Climate-Change-Fueled Extreme Drought

With exacerbating climate change, the current reservoir storage capacity in South Korea is insufficient to meet the future scheduled water demand. No study has yet evaluated the effects of applying the water supply adjustment standard (Standard) and activating the reservoir emergency storage in response to extreme drought. The main objective is to assess the effects of applying Standard and activating emergency storage in meeting the water demand under extreme drought at six multipurpose reservoirs (Andong, Gimcheon-Buhang, Gunwi, Hapcheon, Imha, and Milyang) in the Nakdong River Basin, South Korea. We built a reservoir simulation model (HEC-ResSim), determined the extreme drought scenarios, and emergency storage capacity. We evaluated three reservoir operation cases (general operation, regular Standard, and revised Standard) from 2011 to 2100. The results show that applying the Standard and activating the emergency storage are effective in meeting the future water demand during extreme drought. In conclusion, we need to secure 110 million cubic meters (MCM) (Hapcheon reservoir) and 8 MCM (Gunwi reservoir) of water to reduce the number of days in the emergency stage. This research serves as a fundamental study that can help establish Standard and emergency storage activation criteria for other multipurpose reservoirs in preparation for extreme drought