The effects of dam removal on sea level and the Mekong River region as a proxy for climate sensitive communities

Abstract

Little research has been done on the short and long term effects of dam removal on local and global sea level. Local communities neighboring dams, specifically in areas that are already vulnerable to the risks of sea level rise, need a better understanding of how dam removal will impact them before considering the removal process. As the longest river in Southeast Asia, the Mekong provides water and food to millions of people before draining into the South China Sea. With 11 main hydroelectric dams along the course of the river, the distribution of energy, water, and fish vary for neighboring communities. Fisheries are notably affected as dams obstruct passageways as well as reduce necessary inland flood areas crucial for species reproduction. Recently, in Vietnam and other developing countries, dam collapses have become more common given inadequate planning and preparation for disasters, prompting consideration of dam removal in these areas. Additionally, the communities surrounding the drainage area of the Mekong River are notably at risk for rising sea levels due to climate change (Clark et al., 2016). To better assess the consequences of dam removal along the coast of Southeast Asia, we use the unique spatial patterns of sea level change associated with reservoir impoundment and removal to project local sea level changes under two different dam removal scenarios. These projections are then analyzed in relation to local demographics of the affected areas. While changes in water impoundment will not have a significant impact on global sea level projections when compared to other components of sea level rise, including thermal expansion and glacial melt, our findings yield noticeable changes in local sea level, including sea level falls near megacities such as Bangkok and Ho Chi Minh City. Southeast Asia is highly vulnerable to sea level related damages and relocations; the removal of dams will result in less severe coastal flood levels and support continuous availability of fish to dependent regions along the river, potentially supporting dam removal initiatives in this area and other climate-sensitive regions.>