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Reservoirs and Dams
Published in F.G.H. Blyth, M. H. de Freitas, A Geology for Engineers, 2017
F.G.H. Blyth, M. H. de Freitas
Valleys exist because weathering and erosion have been accentuated at their location; weathered, compressible foundations, and unstable slopes, must be expected near ground level. Stress relief is associated with uplift and erosion (p. 160), and with the excavation of foundations; it can markedly affect the frequency of jointing in a rock valley and the aperture of such fractures (see Grand Coulee Dam, p. 248). Valleys eroded at a time when their rivers were draining to a sea level that was lower than at present (p. 42) are likely to have become a site of deposition following the recovery of sea level to its present elevation. These buried valleys (q.v.) may contain thick sequences of weak, compressible sediment such as silt, peat and clay, interbedded with stronger deposits of sand and gravel. Glaciated valleys may contain till beneath their more recent alluvium.
The Laws of Nuclear Heat Transfer
Published in Robert E. Masterson, Nuclear Reactor Thermal Hydraulics, 2019
However, since plants on the Earth’s surface also absorb carbon dioxide and emit large amounts of oxygen, biological feedback loops may actually reduce the amount of global warming that is predicted to occur without their contributions. Finally, some scientists also believe that global warming is partially due to natural causes and that the Earth is between two ice ages—the last of which occurred about 10,000 years ago. At the end of this ice age, the receding glaciers in North America created the Great Lakes and changed the course of the Columbia River in Eastern Washington State to create the Grand Coulee, which can be seen in Figure 10.15. At the base of the Grand Coulee, they also created one of the largest waterfalls in the history of the Earth. The remains of this gigantic waterfall (which is shown on the left-hand side of Figure 10.15) can still be seen in Eastern Washington today at the Dry Falls National Monument. This waterfall was approximately 1,000 times larger than Niagara Falls is today, and its floodwaters created one of the greatest floods in the history of the Earth. More information about Dry Falls, the Grand Coulee, and this great flood can be found at https://en.wikipedia.org/wiki/Grand_Couleehttps://en.wikipedia.org/wiki/Dry_Falls
Cavitation in Spillways and Energy Dissipators
Published in R. M. Khatsuria, Hydraulics of Spillways and Energy Dissipators, 2004
If curvature away from the flow is too abrupt or severe, low-pressure areas and cavitation can result. In the earlier designs of chute spillways, the convex curvature at the change of grade used to be in the form of a combination of circular arcs. Theoretically, such a transition is a trajectory as described by Equation 25, Chapter 5. The damage caused due to inadequacy in transition can be somewhat like that shown in Figure 3. Damage on the spillway face of the Grand Coulee Dam, U.S.A., can be cited as an example. Transverse grooves in flow surfaces are represented by gate slots, gate grooves, stoplog slots, etc. The flow action and damage locations are indicated in Figure 4.
Approaching obsolescence? A multi-criteria analysis of high-risk dams in the United States Pacific Northwest
Published in International Journal of Water Resources Development, 2022
Alexander C. Nagel, Thomas Ptak
Despite challenges shaped by the natural environment, population centres throughout the Willamette Valley have grown steadily since the early 19th century, facilitated by infrastructure projects that improved transportation and standards of living (Reisner, 1986). The United States reclamation era, stimulating projects such as the Boulder Canyon (Hoover Dam) and Columbia Basin (Bonneville and Grand Coulee Dams), spearheaded the transition to dam-based watershed management for water rights holders and regulatory bodies in the Willamette Valley (Robbins, 2017). Perceptions evolved that the watershed’s hydrology could be profitable if managed accordingly (Wilkinson, 1992). Lack of environmental regulation and congressional mandate by three federal flood control acts in 1936, 1944 and 1960 opened the floodgates for development of the WRBRS (United States Congress, 1960). The 13 structures that now occupy the Willamette Watershed produced a dramatic transformation from a series of energetic and variable tributaries to a chain of lakes tamed by flood and hydropower focused flow regimes (Magilligan et al., 2016). Table 1 provides a general orientation of the functions and characteristics of the structures to be analysed.
Bringing twentieth-century water projects into the twenty-first century: The case for revisiting dam operations in Alberta
Published in Canadian Water Resources Journal / Revue canadienne des ressources hydriques, 2018
Reed D. Benson, Stewart B. Rood
AEP followed a similar process in developing operations plans for two later projects in the SSRB. The Pine Coulee Project on Willow Creek (1996 to 2000) and the Little Bow/Highwood River Project that resulted in the Twin Valley Dam (2000 to 2004) were much smaller and less controversial than the Oldman River Dam. Like the Oldman project, however, both involved open reviews with joint federal and provincial environmental assessment committees. These examined a broad range of considerations including environmental impacts at the project sites and extending along the river corridors, along with direct and indirect social, cultural and economic impacts. Thus, AEP recognized the value and importance of a comprehensive and inclusive approach to operations planning for new water projects, but it has not yet engaged in a similar process to review and renew its plans for existing projects. It has, however, made notable changes in the operating plans and practices at some projects, as explained in the following section.