Important Considerations in Dam RemovalEnvironmental Training Resource
August 9, 2013 — 3,540 views
Dam removal is said to be a process which can help in restoration of rivers and its habitat. In removal of dams, the engineers must find answers and a whole lot of data to understand the process of removal and post removal effects of a dam. Since this data is currently scarce, it is proving to be a challenging process for engineers. Before the process of removal of a dam is started, engineers need to pay close attention to the possible effects it will have on the surrounding habitat.
Dam removal in the past has shown that drastic morphologic changes have taken place. On removal of the Newaygo Dam in Michigan, 40% of the stored sediment went downstream immediately.
Sediment management plays a vital role in the process of removing a dam. Sediment which could be stuck behind a dam could drastically affect the costs and also could have an environmental impact on the dam removal. Sediment management is an important part of the dam removal process. In order to deal effectively with this it is important to do an in depth decision making process for removing the dam. On the other hand, if the sediment is released downstream, it could bury the downstream habitat, cause water quality concerns, threaten infrastructure, change channel dynamics and increase flood hazards.
Dams have a huge impact on natural rivers, and are viewed negatively by biologists. The period of transition from a reservoir back to a river is a particularly vulnerable period for organisms, and events and circumstances occurring during this initial phase may determine the pattern of ecological recovery.
There is a huge potential for ecosystems to return to conditions similar to the pre-dam state, or to a new and unfamiliar state. Huge changes in the physical structure of the river can result in dramatic ecological changes which may have long-term effects on the nature of recovery of the river.
Previous studies done after dam removal show that the life downstream returned to the pre-dam conditions with plant population and fish population returning within spans of time ranging from 3 months to 1 year of the dam removal.
Societal and Other Considerations
There are several opinions, values and concerns held by environmentalists and communities benefitted or affected by the dam which affect will, in turn, the decision making process of dam removal. Nostalgic memories associated with the dam, and aesthetic value given to the dam can impact the fate of a dam. These factors cannot be quantified monetarily and therefore create a challenging situation. Removal of a dam can also impact the land prices around the area for better or worse. People who have purchased lands around the reservoir are used to having high water levels and available water supply at hand, which creates a new challenge in the process of dam removal.
Many people enjoy the benefits of the non-natural water source, which creates fishing opportunities and wetlands. These add to the sentiments of the people and create a huge pressure upon the decision of dam removal.