The Challenges of Dam Removal and River Restoration

River restoration is a societal goal in the United States. This collection of 14 research papers focuses on our current understanding of the impacts of removing dams and the role of dam removal in the larger context of river restoration. The chapters are grouped by topic: (1) assessment of existing dams, strategies to determine impounded legacy sediments, and evaluating whether or not to remove the dams; (2) case studies of the hydrologic, sediment, and ecosystem impacts of recent dam removals; (3) assessment of river restoration by modifying flows or removing dams; and (4) the concept of river restoration in the context of historic changes in river systems.
Sediment management at small dam removal sites
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Published:January 01, 2013
Abstract
The removal of obsolete and unsafe dams for safety, environmental, or economic purposes frequently involves the exploration of sediments trapped within the impoundment and the subsequent assessment of sediment management needs and techniques. Sediment management planning requires a thorough understanding of the watershed’s surficial geology, topography, land cover, land use, and hydrology. The behavior of sediments is influenced by their age, consolidation, and stratigraphy. All watersheds have a history that helps forecast sediment loads, quality, gradation, and stratigraphy. Impounded sediment deposits may include coarse deltas and foreset slopes, fine or coarse bottom deposits, cohesive or organic matter, and wedge deposits immediately behind the dam. Some watersheds have anthropogenic pollutants from agricultural activities, mining, industries, or urban runoff.
The volume and rate of sediment release during and after small dam removal can be limited by active management plans to reduce potential downstream impacts. Management strategies include natural erosion, phased breaches and drawdowns, natural revegetation of sediment surfaces, pre-excavation of an upstream channel, hazardous waste removal or containment, flow bypass plans, and sediment dredging.
- bedload
- characterization
- chlorinated hydrocarbons
- Connecticut
- dams
- environmental management
- excavations
- halogenated hydrocarbons
- hazardous waste
- hydraulics
- hydrology
- landfills
- Massachusetts
- New York
- North Carolina
- organic compounds
- PCBs
- pollution
- reclamation
- risk assessment
- safety
- sanitary landfills
- sediment traps
- siltation
- soil pollution
- tailings dams
- United States
- waste disposal sites
- water management
- watersheds
- Fort Edward Dam
- Union City Dam
- Nowalk Mill Pond
- Chase Brass Dam
- Carbonton Dam
- T&H Dam