China
Africa
Explore chapters and articles related to this topic
Reservoir Sediment Management Strategies
Published in Kumkum Bhattacharyya, Vijay P. Singh, Reservoir Sedimentation, 2019
Kumkum Bhattacharyya, Vijay P. Singh
Dam removal could be another option to reinstate the original river reach as demonstrated by Doyle et al. (2002, 2003), East et al. (2015), Grant and Lewis (2015), and Randle et al. (2015). Grant and Lewis (2015) have analyzed scientific studies focusing on the sediment-related effects of individual dam removals. Examples of detailed case studies are also found in Oregon (Stewart & Grant 2006; Walter & Tullos 2010; Major et al. 2012), Washington (Major et al. 2017), New England (Magilligan et al. 2016), and across the Midwest and Northeast United States (Sawaske & Freyberg 2012). They observed that dam removal intrigues river engineers and fluvial geomorphologists because it signifies a coupled upstream/downstream problem of erosion, transport, and depositional outcome of sediment. A dam removal drops the base level of the river upstream of the dam, increasing the hydraulic gradient through the former reservoir, and subjecting sediments stored in the reservoir to fluvial erosion and entrainment.
After the Causal Assessment: Using the Findings
Published in Susan B. Norton, Susan M. Cormier, Glenn W. Suter, Ecological Causal Assessment, 2014
Susan B. Norton, Scot E. Hagerthey, Glenn W. Suter
Knowing the causes and sources of effects can help establish the time scale of recovery. Recovery of fish populations and macroinvertebrate assemblages from temporary disturbances including chemical spills or treatments, floods or droughts, construction activity, and invasive organism removal, can range from less than 1 year to 6 years (Niemi et al., 1990; Detenbeck et al., 1992). These time periods are consistent with observed organism reactions following management actions that create abrupt changes. Some biological improvements from dam removal are immediate, for example, increased access of fish to spawning habitat. Riverine taxa tend to replace those adapted to slow-moving water within a year of dam removal (Stanley and Doyle, 2003). The rate of improvement in communities downstream and immediately upstream of dams can take longer, in the order of years, due to the greater volume of accumulated fine sediments inhibiting recovery (Stanley and Doyle, 2003; Feld et al., 2011). Relatively short recovery times for macroinvertebrates have also been observed after excluding livestock from streams (3 years) and treating mine waste in streams (10 years for macroinvertebrates and 3–9 years for fish) (Meals et al., 2010; Spears et al., 2011). The recovery of fish populations following in-stream habitat restoration has been reported, but questions remain about whether those improvements are sustained over time (Meals et al., 2010; Feld et al., 2011).
Global water infrastructure: state of the art review
Published in International Journal of Water Resources Development, 2019
Now, some stakeholder groups question whether all dams are needed, and some are slated for removal (Doyle, Harbor, & Stanley, 2003). Trapping of sediments by dams is said to be an increasingly serious environmental issue, which might require some to be removed (Robbins, 2017). There is even discussion of removing major dams, such as the Glen Canyon Dam on the Colorado River (Moab Sun News, 2015). It is difficult and disruptive to remove a dam, and great care must be taken. The question of dam removal has risen in China (Miao, Borthwick, Liu, & Liu, 2015), and Japan has initiated its first dam-removal project (Hatsuko, 2004). A recent high-profile example of dam removal in the US is the 210-feet-high Glines Canyon Dam, on the Elwha River in Washington State. Some 865 dams have been removed in the US over the last 20 years (Nijhuis, 2015). The US Geological Survey has created a database of scientific studies of dam removal (Duda et al., 2016).
Simulation and control of sediment transport due to dam removal
Published in Journal of Applied Water Engineering and Research, 2018
When a dam is significantly deteriorated and no longer able to serve the purpose for which it was constructed, or the costs of repair and maintenance exceed the expected benefits, the dam may need to be decommissioned (or removed). In the United States, dam removal in a river or stream is considered as an effective engineering approach to restore river ecosystems. However, the downstream impact of sediments released from the reservoir post-dam removal is a major concern. For reservoirs with large sediment deposits, released sediments may significantly change the river morphology in both the reservoir and the downstream channels (Cui & Wilcox 2008). Before decommissioning a dam, it is important to study sediment transport and morphological changes upstream and downstream of the dam site that may result from dam removal. Engineering planning and decision-making dealing with dam removal rely heavily on predictive simulation results to assess environmental impacts due to releases of sediment and water from reservoirs (Konrad 2009).
Ice in reservoirs and regulated rivers
Published in International Journal of River Basin Management, 2022
Mikko Huokuna, Mike Morris, Spyros Beltaos, Brian C. Burrell
During the period that a dam was in place, the river regime and land use may have changed. Stream characteristics and aquatic habitat, and the population and development along the river adjust to the conditions existing during decades the dam and reservoir are in place. Removal of dams that provided major attenuation of downstream peak flows and re-establishment of greater peak flows to the downstream channel could result in altered channel form and widening, bank erosion and instability, changed flood plains, increased flooding, and alteration and destruction of fish habitat (OMNR 2011). The quality, quantity, and transport of reservoir sediments after dam removal may also affect downstream channel conditions, water quality, and fish habitat.