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Intakes and outlets
Published in Willi H. Hager, Anton J. Schleiss, Robert M. Boes, Michael Pfister, Hydraulic Engineering of Dams, 2020
Willi H. Hager, Anton J. Schleiss, Robert M. Boes, Michael Pfister
A physical model of a typical low-level outlet was built at the Laboratory of Hydraulics, Hydrology and Glaciology (VAW), ETH Zurich, Switzerland (Figure 8.82a). Two high-head pumps provided a maximum energy head at the gate of HE = 30 m at a water discharge of QW ≈ 600 l/s. A rectangular sharp-crested gate without gate slots was installed to control the discharge (Figure 8.82b). The gate had a maximum opening of amax = 0.25 m and was operated by a stepper motor allowing for a continuous variation of the gate opening a. The rectangular tunnel had a constant width of wt = 0.2 m and an approach flow height ho equaling the maximum gate height hg, i.e., ho = hg = amax = 0.25 m upstream of the gate, that increased to the tunnel height (invert to crown) of ht = 0.3 m downstream of the gate (Figure 8.82b).
Introduction
Published in Geraldo Magela Pereira, Spillway Design – Step by Step, 2020
The model studies were conducted by the Laboratory of Hydraulic, Hydrology and Glaciology of the Federal Institute of Technology of Zurich. The water level of the reservoir was fixed at elevation 492,25 m, with freeboard of 1,75 m. Figure 1.12D shows the refurbished project.
Energy loss on stepped spillways
Published in L. Berga, J.M. Buil, C. Jofré, S. Chonggang, Roller Compacted Concrete Dams, 2018
G. Valentin, P.U. Volkart, H.-E. Minor
At the Laboratory of Hydraulics, Hydrology and Glaciology (VAW) of the Swiss Federal Institute of Technology (ETH) several investigations on stepped spillways were conducted. There were two different hydraulic models, one allowing for different slope angles (Φ = 30°, 40° and 50°) to reach uniform flow conditions (Figure 1) and the second one having a standard WES-crest shape and a constant slope angle of Φ = 50° (Figure 2). Both chutes are 0.5 m wide with one side wall constructed of glass. The vertical velocity profiles, as well as the air-concentration-profiles were measured using a fiber-optic probe (Boes 2000).
Underlying topography and forest height estimation from SAR tomography based on a nonparametric spectrum estimation method with low sidelobes
Published in International Journal of Digital Earth, 2022
Youjun Wang, Xing Peng, Qinghua Xie, Xinwu Li, Xiaomin Luo, Yanan Du, Bing Zhang
The underlying topography and forest height are important information in hydrology, geology, geomorphology, civil engineering construction, forest investigation, glaciology, volcanology, and the modeling of natural disasters such as floods and landslides (Mukherjee et al. 2013). Synthetic aperture radar (SAR) tomography (TomoSAR), as a newly developed microwave remote sensing technique (Reigber and Moreira 2000; Pardini, Cazcarra-Bes, and Papathanassiou 2021), has been proven to be a potential approach for regional – or even global-scale underlying topography and forest height inversion (Aghababaee et al. 2020). In particular, the long-wavelength SAR systems (such as L- and P-band systems) have a higher penetration ability than the short-wavelength SAR systems (e.g. X-band), and they can penetrate the forest canopy to the ground (Huang et al. 2017).
How does sediment supply influence refugia availability in river widenings?
Published in Journal of Ecohydraulics, 2021
Cristina Rachelly, Kate L. Mathers, Christine Weber, Volker Weitbrecht, Robert M. Boes, David F. Vetsch
Laboratory experiments investigating the dynamic river widening process were performed at the Laboratory of Hydraulics, Hydrology and Glaciology (VAW) at ETH Zurich. All hydraulic (FOEN 2017), sedimentological (Huwiler and Stocker 2019), and geometric (FOEN 2015) parameters were chosen to correspond to the Kander River. The laboratory setup consisted of a straight, trapezoidal channel with fixed banks and a mobile bed. The channel with a slope of 0.01 is 0.89 m wide and 31.6 m long. One bank of the channel can be partially removed to enable lateral erosion of the adjacent floodplain which consists of the same mobile bed material and longitudinal slope as the channel (Figure 2). Fixed banks delineate the widening area, representing hidden bank protection measures to limit lateral erosion. All data collected in the laboratory model were then upscaled with a Froude scale factor of λ = 30. In prototype scale, the width of the initial channel is 26.8 m, the widening can assume a maximum width of 107.4 m, i.e. a widening ratio of up to 4, the length of the widening is 708 m, i.e. long enough to be hydraulically effective (Hunzinger 1998), and the maximum widening area is 63,800 m2.
Atomistic study on the anomalous temperature-dependent dynamic tensile strength of ice under shock loading
Published in Philosophical Magazine, 2021
Y. Y. Chen, K. L. Xiao, J. Z. Yue, Q. Y. Yin, X. Q. Wu, C. G. Huang
Ice constitutes the second most massive solid after the lithosphere globally and plays an essential role in the water cycle. The dynamic behaviour of ice under high strain-rate loading is an essential issue in glaciology, geophysics, and polar engineering. For example, the accelerated flow of fractured glaciers resulting from the collapse of the Larsen B ice shelf, drifting in response to tides [1], significantly affected the polar landforms and ecosystems and became a hotspot of global warming [2]. A better understanding of the dynamic properties of ice is beneficial for disaster evaluation and mitigation of the collapse event. Besides the earth, ice is also widely distributed in the solar system [3], urging the research on the dynamic behaviour for extraterrestrial life detection and exploration of some icy moons.