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Strong wind characteristics and turbulence
Published in John D. Holmes, Seifu A. Bekele, Wind Loading of Structures, 2020
John D. Holmes, Seifu A. Bekele
As the wind approaches a shallow feature, its speed first reduces slightly as it encounters the beginning of the slope upwards. It then gradually increases in speed as it flows up the slope towards the crest. The maximum speed-up occurs at the crest, or slightly upwind of it. Beyond the crest, the flow speed gradually reduces to a value close to the value that occurs well upwind of the topographic feature; the adjustment is somewhat faster for a feature with a downwind slope, such as a ridge, than for an escarpment with a plateau downwind of the crest.
Origin and recharge rates of alluvial ground waters, Eastern Desert, Egypt
Published in M.M. Sherif, V.P. Singh, M. Al-Rashed, Hydrology and Water Resources, 2020
Mohamed Sultan, Hazem Gheith, Neil C. Sturchio, Zeinhom El Alfy, Shuhab Danishwar
The subject of this study is the ground waters in the shallow (< 150 m) alluvial and limestone aquifers of Wadi El-Tarfa (Fig. 1) and the surrounding valleys, namely Asyuti, Wadi Qena, and Wadi Hammamat. Here, Quaternary deposits comprise wadi and floodplain deposits. The alluvial deposits were eroded from the dissected plateau, and the Red Sea hills and were deposited within the valleys. The floodplain deposits of the Nile Valley are made up of relatively thin (7 m) Holocene units of fine mud and silt deposited by repeated seasonal floods during the past 8,000 y. The sediments are underlain by thicker deposits of middle Pleistocene sand and gravel under the Nile Valley proper. The Quaternary deposits rest on karstified carbonates of Eocene and Upper Cretaceous ages. The carbonates are underlain by Paleozoic-Mesozoic Nubian sandstones that host nonrenewable fossil waters under high pressure (Fig. 2).
Lithology and landforms
Published in Richard J. Chorley, Stanley A. Schumm, David E. Sugden, Geomorphology, 2019
Richard J. Chorley, Stanley A. Schumm, David E. Sugden
Basalt and ignimbrite flows produce flat-topped plateaus with cliffed and stepped edges controlled by the vertical jointing and flow bedding, respectively. There is commonly an absence of river erosion on the plateau tops because the drainage is conducted underground by the joint systems, permeable ash and flow cavities, but deep weathering of the basalts (especially where closely jointed in the humid tropics) and areas of poorly welded tuffs may lead to considerable piecemeal reduction of volcanic plateaus by erosion. Normally the most rapid and spectacular erosion takes place around the plateau margins, especially by means of landslides produced by weathering and spring sapping at the base of the flows. Basalt plateaus, for example that of the Snake River, are bordered by a number of deep, steep-sided, theatre-headed ‘alcoves’ bordered by talus at the sides, but not at the heads, which are aggressively backcutting at a zone of springs and rapid weathering (Figure 8.12). The advanced erosion of a lava plateau produces an assemblage of mesas and buttes, and may also lead to the superimposition on the underlying rocks of some drainage lines developed on the lava surface. Smaller-scale flows can influence landform development by diverting surface drainage or by filling pre-existing valleys leading to ‘inversion of relief’ (Figure 8.13).
Mapping of lakes in the Qinghai-Tibet Plateau from 2016 to 2021: trend and potential regularity
Published in International Journal of Digital Earth, 2022
Zhichong Yang, Si-Bo Duan, Xiaoai Dai, Yingwei Sun, Meng Liu
The TP between 26°00′−39°47′N and 73°19′−104°47′E is approximately 2,800 km long from east to west, and 300–1,500 km wide from north to south. It has a total area of approximately 2.5 million km2 and an average altitude of approximately 4,500 m (Baumann et al. 2009). The geographic location and altitude of the TP are shown in Figure 1. The climate of the TP is a comprehensive effect of the East Asian and South Asian monsoons and the westerlies (Schiemann, Luethi, and Schaer 2009). Its unique environmental conditions produce a special plateau climate, with strong solar radiation, low air temperatures, large daily temperature variations, and small differences between annual mean temperatures (Yao et al. 2012). The annual average temperature is 1.6°C, with a minimum temperature of −1 to −7°C in January, and a maximum temperature of 7–15°C in July. The annual cumulative precipitation is approximately 413.6 mm.
Opportunity and challenges in large-scale geothermal energy exploitation in China
Published in Critical Reviews in Environmental Science and Technology, 2022
Yuanan Hu, Hefa Cheng, Shu Tao
With over 600 geothermal areas/sites, including hot springs, geysers, and hot rivers, Tibet is a global geothermal hotspot (Wang et al., 2017). The total geothermal power generation potential in Tibet is estimated to be around 3,000 MW, and most of the high temperature geothermal fields are distributed in the south of Bangongcuo-Nujiang fault zone (Luo et al., 2015; NDRC, 2017a). The Tibetan Plateau is the world’s largest and highest plateau and hosts over 50 mountains with altitudes above 7 km. Despite of the huge amount of geothermal resources available in Tibet, they have been barely exploited, with the exception of the geothermal fields at Yangbaijian and Yangyi (Wang et al., 2017). In general, Tibet has relatively few industrial enterprises, a small population, and poor infrastructure. Thus, geothermal power could only be developed in the relatively more densely populated and economically more developed counties to meet the local electricity demand (NDRC, 2017a).