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Setting and History
Published in Malchus B. Baker, Peter F. Ffolliott, Leonard F. DeBano, Daniel G. Neary, Riparian Areas of the Southwestern United States, 2003
Leonard F. DeBano, Larry J. Schmidt
The age of the rocks in the Basin and Range Province ranges from Precambrian to Quaternary, with igneous, metamorphic and sedimentary rocks being well represented throughout the province. Igneous rocks include granites and volcanic rocks.5 The sedimentary rocks are found in the intermountain basins where gravels, sands, silts, clays, marl, gypsum and salt represent a complex combination of fluvial, lacustrine, colluvial and alluvial fan deposits forming basin aquifers as deep as 4300 ft.9 The Colorado Plateau, which ranges in elevation from 3300 to 14,000 ft and encompasses nearly 154,400 mi2 in the Four Corners area,8 is composed of thick layers of gently dipping sedimentary rocks that eroded to form prominent plateaus dissected by deep canyons. Volcanoes erupting during the late Cenozoic formed prominent mountains such as the San Francisco Peaks near Flagstaff, Arizona.10 The landscape is deeply dissected by canyons, the most notable being the Grand Canyon in Arizona.
Wind action and arid regions
Published in F.G. Bell, Geological Hazards, 1999
Yet another type of fluvial landscape developed in arid regions is found where there are thick surface formations of more or less horizontally bedded sedimentary rocks. Large rivers coming from outside the region frequently flow in canyons, such as the Colorado River in the southwest of the United States and the Fish River in Namibia. The plateau lands that characterize such areas are interrupted by buttes and mesas, and by escarpments or cuestas. Such landscapes are typified by the Colorado Plateau, and are found in the semi-arid and arid areas of southern Africa.
The hydropower industry
Published in Urban Kjellén, Eirik Albrechtsen, Prevention of Accidents and Unwanted Occurrences, 2017
Urban Kjellén, Eirik Albrechtsen
Dam projects utilise the water pressure that is built up by the water column in the dam. This type of project is often located in narrow canyons, where the physical environment involves steep slopes with falling rock and landslide risks. Dams located on the plains need to be large to generate enough flow to compensate for the lower drop. A dam break involving large volumes of water and a large population density downstream of the dam may have catastrophic consequences.
Numerical study of flow structure and pedestrian-level wind comfort inside urban street canyons
Published in Journal of the Royal Society of New Zealand, 2021
Purvi P. Pancholy, Kevin Clemens, Patrick Geoghegan, Mark Jermy, Miguel Moyers-Gonzalez, Phillip L. Wilson
Urban street canyons are places in cities or towns where a street is flanked on both sides by a continuous or almost continuous line of buildings. It is known that these street canyons affect local variations in global environmental and meteorological conditions such as wind speed, wind direction, air pollution, rain direction, and heat radiation (Blocken and Carmeliet 2004; Blocken 2015; Blocken et al. 2016). The goal of the present work is to study how the geometrical features of the canyon and the buildings which define it affect the wind flow structure inside it in order to study not only the broad features of wind canyon flow and their dependence on canyon geometry, but mainly to study the effects of canyon geometry on pedestrian comfort. Our canyons consist of two large buildings of the same spanwise length and streamwise width, representing either identical parallel low buildings or, more likely, quasi-uniform terraced buildings on either side of a street.
Forestry management and water law: comparing Ecuador and Arizona
Published in Water International, 2019
Andrés Martínez Moscoso, Rhett Larson
At first glance, one might think that the nation of Ecuador and the US state of Arizona have little in common with respect to water resource management. Although the two jurisdictions are similar in size, Ecuador is famed for its geographic diversity – ranging from rainforest to coastal mangrove swamps and highland páramos (high plateaus in the Andes Mountains between the tree line and snow line). Ecuador sits atop the Andes mountain range and at the headwaters of the largest river on the planet, the Amazon. On the other hand, Arizona is largely an arid region famous for the Grand Canyon, carved out of desert mountain rock by the Colorado River. Nevertheless, they share one particular water challenge. Both jurisdictions have large upland forests that play a critical role in water resource management. The forests in Ecuador and Arizona, like many such ecosystems around the world, are also threatened by climate change and population growth (Goldman, Benitez, Calvache, & Ramos, 2010). Greater investments in forests, as ‘green infrastructure’ providing critical ecosystem services in water protection, are essential to respond to these challenges (Echevarria, Zavala, Coronel, Montalvo, & Aguirre, 2015). This article examines recent legal innovations in river basins in Ecuador and Arizona, which aim to promote improved forestry management, or ‘green infrastructure’, for the protection of water supplies. This article compares and contrasts these different approaches and suggests lessons from each programme that might improve management in both jurisdictions.
Submarine canyons and slides in the central-west Otway Basin: their morphology, genesis, links to groundwater discharge and tsunamigenic potential
Published in Australian Journal of Earth Sciences, 2023
Sprigg’s (1947, 1948) preliminary investigations of Australia’s southern canyons were followed by those of Conolly and von der Borch (1967) and von der Borch (1968), who also documented the presence of several canyons along the southern coastline of Australia, as well as offshore Perth. These canyons, and a number of additional ones, have since been described along the southern margin of Australia, and these include the Murray Canyons Group (Hill et al., 2005), with the adjacent du Couëdic Canyon to the west and the Bonney Canyon to the east (Currie & Sorokin, 2014), the Albany Canyons to the west of the Great Australian Bight (Exon et al., 2005), the Perth Canyon in increasing detail (Huang et al., 2014; Nanson et al., 2022; Rennie et al., 2009), and the Bass Canyon on the eastern edge of Bass Strait (Mitchell et al., 2007). The mechanisms for initiation and expansion of these canyons have principally been ascribed to fluvial connectivity (Hill et al., 2005, 2009; Nanson et al., 2022; von der Borch, 1968). There remains, however, some ambiguity in the initiating mechanisms for these widespread features around Australia’s southern margin, especially since Mahon and Wallace (2022) recently described Cenozoic incised channels in the Gippsland Basin, which they convincingly argue to have been submarine canyons not formed by fluvial activity. Figure 1 illustrates the distribution and morphology of a series of shelf-incising and blind canyons and slides within the geological Otway Basin (Figure 1, insert). Herein, we use new high-resolution bathymetric mapping to describe their morphology and link these observations with published sub-surface datasets to advance our understanding of their formative processes. In particular, we aim to identify their potential link to groundwater discharges at sea that may trigger canyon formation, and to also examine the potential tsunamigenic processes linked to underwater slides caused by groundwater sapping.