mitigation

Mitigation Measures Against Hydropeaking Effects

Source: 
SINTEF Energy Research
Year: 
2011
Abstract: 

Hydropeaking consists of variations in discharge and water level due to releases of water retained in storage basin to generate electricity according to the market demand. These unnatural flow fluctuations create frequent and rapid variations in terms of flow magnitude, flow velocity, water depth, water temperature, wetted area and sediment transport which also can affect channel morphology. Such changes may lead to degradation of physical conditions and habitats in local ecosystems which directly affect biological communities in rivers. Mitigation measures can enhance the ecological state of rivers and lakes altered by hydropeaking. They are classified into 3 different types: Operational measures place constraints on the hydropower plant regime itself, fixing threshold values for amount of water released; construction measures involves construction of hydraulic structures like retention basins; and in-stream measures are renovation or maintenance works carried out inside the river. Mitigation measures are site-specific and thus local investigations must be carried out to ensure successful implementation of measures. In addition, long-term monitoring and systematic evaluation should be conducted during and after the completion of rehabilitation projects to assess the benefits of measures on local ecosystems. The literature review gathers examples of abatement measures implemented in several countries to mitigate negative impacts of hydropeaking. Examples are classified in a table and sorted by the aim of the measures.

 

Author(s): 

Julie Charmasson and Peggy Zinke

Category: 

Mitigating the Effects of Climate Change on the Water Resources of the Columbia River Basin

Source: 
Climatic Change
Volume: 
62
Year: 
2004
Abstract: 

The potential effects of climate change on the hydrology and water resources of the Columbia River Basin (CRB) were evaluated using simulations from the U.S. Department of Energy and National Center for Atmospheric Research Parallel Climate Model (DOE/NCAR PCM). This study focuses on three climate projections for the 21st century based on a ‘business as usual' (BAU) global emissions scenario, evaluated with respect to a control climate scenario based on static 1995 emissions. Time-varying monthly PCM temperature and precipitation changes werestatistically downscaled and temporally disaggregated to produce daily forcings that drove a macroscale hydrologic simulation model of the Columbia River basin at 1/4-degree spatial resolution.

Author(s): 

Jeffrey T. Payne, Andrew W. Wood, Alan F. Hamlet, Richard N. Palmer and Dennis P. Lettenmaier

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Chapter 9: Dams and mitigation of their effects

Volume: 
Nat'l Acad. Press, Washington, DC
Year: 
1996
Abstract: 

This paper examines the effects of dam construction and operation in the Columbia River Basin on salmon populations. While the hydrograph of the Columbia River has been significantly impacted by dams, the seasonality of regulated flow on the Snake River has been less affected. The Snake River storage has been used for agricultural diversion while the Columbia has been for electrical generation. The reservoir system has effects on flow velocities, water chemistry (nitrogen supersaturation), habitat availability and reliability, and stream temperatures. Dams block about one third of the Columbia River watershed to access by anadromous fish.
Effects of Dams on Salmon;
Fish kills occur as a result of several characteristics of dams. Bruising, descailing, and stress caused by by-pass facilities; susceptibility to prey following delivery from by-pass to outfall; estuary damage; effects on the homing ability of fish; limited success in fish use of by-pass facilities. The effect of migration speed on smolt survival is uncertain but assumed to have an impact. More research is necessary.
Mitigation of Dam's Effects on Salmon:
Seven measures for mitigation of dams' effects on salmon are discussed
1. Fish passage facilities 2. Predator control 3. Transportation 4. Spill 5. Flow augmentation 6. Reservoir drawdown 7. Dam removal.

Author(s): 

National Research Council , NRC

Contact: 
Notes: 
Category: 

Effectiveness of water release as mitigation for hydroelectic impacts to fish

Volume: 
August, 1995 pp81-96
Year: 
1995
Abstract: 

Utility companies release water to mitigate the effects of hydroelectric projects on fish habitats. Utility companies, government agencies, and research communities in Canada, the United States, Europe, New Zealand, and Australia were surveyed as part of a Canadian Electrical Association study to evaluate the effectiveness of water release as a mitigation. Respondents identified only 28 projects in which water was released specifically to protect fish habitats. Fewer than half of these projects (12) were judged as being effective. Six case histories with preimpact assessment and postimpact monitoring were reviewed. In four cases fish habitat or fish populations or both were maintained; in two cases they were not. The effectiveness of water release differed among rivers and fish species, and was greatest when designed to meet the habitat requirements of each life-history stage. A review of the literature did not support the theory that a particular fraction of the mean annual flow provides the best fish habitat. Although smaller changes in the flow regime had smaller effects, increasing minimum flows above those historically observed did not necessarily increase fish production.

Author(s): 

Lewis , A.F. , Mitchell , A.C.

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