scholarly journals Leaky barriers: leaky enough for fish to pass?

2021 ◽  
Vol 8 (3) ◽  
Author(s):  
Stephanie Müller ◽  
Catherine A. M. E. Wilson ◽  
Pablo Ouro ◽  
Joanne Cable
Keyword(s):  
Flood Management ◽  
Fish Passage ◽  
River Channels ◽  
Flow Conditions ◽  
Velocity Measurements ◽  
Time Flow ◽  
Migration Barriers ◽  
Acoustic Doppler Velocimetry ◽  
Downstream Communities ◽  
Local Materials

Perceived as environmental-friendly hydraulic structures, leaky barriers used for natural flood management are introduced into rivers, potentially creating migration barriers for fish. Using sustainable, local materials to construct wooden barriers across river channels in upper catchments, these barriers aim to slow down the flow, reduce flood peaks and attenuate the flow reaching downstream communities. Yet little is known about their impact on hydrodynamics and fish passage. Here, we examined two model barrier designs under 100% and 80% bankfull flow conditions in an open channel flume. These barriers included a porous and a non-porous design, with the latter emulating the natural accumulation of brush, sediment and leaf material between logs over time. Flow visualization and velocity measurements recorded with acoustic Doppler velocimetry characterized the flow field upstream and downstream of the barriers. Our fish behavioural studies revealed that juvenile salmon ( Salmo salar ) movement between downstream and upstream sections of the flume was inhibited by barrier design rather than discharge, influencing upstream fish passage and their spatial preference, indicating the importance of barrier design criteria to facilitate fish movement.

scholarly journals Optimization of the flow conditions in the spawning ground of the Chinese sturgeon (Acipenser sinensis) through Gezhouba Dam generating units

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Anyang Huang ◽  
Jinzhong Yao ◽  
Jiazhi Zhu ◽  
Xingchen Gao ◽  
Wei Jiang
Keyword(s):  
Spawning Ground ◽  
Chinese Sturgeon ◽  
Flow Conditions ◽  
Velocity Measurements ◽  
Acipenser Sinensis ◽  
Critically Endangered Species ◽  
Gezhouba Dam ◽  
Opening Mode ◽  
Suitable Area ◽  
Good Agreement

AbstractChinese sturgeon (Acipenser sinensis) is a critically endangered species, and waters downstream from Gezhouba Dam are the only known spawning ground. To optimize the velocity conditions in the spawning ground by controlling the opening mode of Gezhouba Dam generator units, a mathematical model of Chinese sturgeon spawning ground was established in FLOW-3D. The model was evaluated with velocity measurements, and the results were determined to be in good agreement. By inverting the 2016–2019 field monitoring results, the model shows that the preferred velocity range for Chinese sturgeon spawning is 0.6–1.5 m/s. Velocity fields of different opening modes of the generator units were simulated with identical discharge. The suitable-velocity area was maximal when all units of Dajiang Plant of Gezhouba Dam were open. For discharges below 12,000 m3/s, most of the area was suitable; for discharges above 12,000 m3/s, the suitable area rapidly decreased with increasing discharge. A comparison of suitable areas under high-flow showed that at discharges of 12,000–15,000 m3/s, opening 11–13 units on the left side was optimal. For discharges above 15,000 m3/s, all units should be open. We used these results to recommend a new operation scheme to support the conservation of Chinese sturgeon.

Velocity measurements close to the bed in a wave tank

1970 ◽  
Vol 42 (1) ◽  
pp. 111-123 ◽  
Author(s):  
J. F. A. Sleath
Keyword(s):  
Velocity Distribution ◽  
Vortex Formation ◽  
Reynolds Numbers ◽  
Flow Conditions ◽  
Velocity Measurements ◽  
Dominant Effect ◽  
Wave Tank ◽  
High Reynolds Numbers ◽  
High Reynolds ◽  
Laminar Flow Conditions

Measurements of the velocity distribution close to the bed have been made under laminar flow conditions in a wave tank. The classical solution for the velocity distribution was found to be valid when the bed was smooth, but considerable deviations between theory and experiment were observed with beds of sand. It is suggested that these deviations were caused by vortex formation around the grains of sand. The similarity between the velocity profiles obtained in these tests and those reported by other writers under supposedly turbulent conditions suggests that even at high Reynolds numbers vortex formation may continue to be the dominant effect in oscillatory boundary layers of this sort.

Geomorphological numerical modelling of woody dams in CAESAR-Lisflood

2021 ◽  
Author(s):  
Josh Wolstenholme ◽  
Christopher Skinner ◽  
David Milan ◽  
Daniel Parsons
Keyword(s):  
Flood Risk ◽  
Flood Management ◽  
River Channels ◽  
Sensitivity Testing ◽  
Spatial And Temporal Scales ◽  
Natural Processes ◽  
Natural Wood ◽  
Long Term Impact ◽  
Morphology Influence

<p>Natural flood management (NFM) promotes the sustainable enhancement of natural fluvial processes to reduce flooding (SEPA, 2015; Wilkinson et al., 2019), and is increasingly popular for use by community groups, contractors and governments (Kay et al., 2019). Reintroduction of wood to a river channel is a popular form of NFM often achieved through seeding natural logjams, or with an emphasis on engineering through installing woody dams (WDs). WDs are currently installed or being installed in catchments in an effort to reduce flood risk, through hydrograph attenuation, increase biodiversity and improve geomorphic heterogeneity (Wenzel et al., 2014; Burgess-Gamble et al., 2017; Grabowski et al., 2019). A further objective is to emulate the effect of natural wood found in river channels by partially, or completely, blocking the channel to accelerate the recruitment of natural wood as part of the natural wood cycle (Addy & Wilkinson, 2016).</p><p>There is a growing body of evidence supporting the benefits of NFM, however, the hydrogeomorphic effects of WDs are less well understood (Dadson et al., 2017). There is little scientific underpinning concerning the long-term impact of these features upon hydrogeomorphology at reach and catchment-scales. Very few numerically based studies consider the influence of sediment transport on WDs, and how changes in local bed morphology influence their effectiveness. Most NFM research to date has focused upon modelling the effectiveness of local NFM measures in small catchments (<10 km<sup>2</sup>) (Dadson et al., 2017), with less work evident at larger spatial and temporal scales (Kay et al., 2019; Wilkinson et al., 2019).</p><p>There is a need for a verified tool that is able to represent WDs accounting for geomorphic processes and interactions between the dams and morphodynamics, different design specifications of dams, and changing efficacy due to geomorphic evolution. We present the new CAESAR-Lisflood (Coulthard et al., 2013) “Working with Natural Processes” toolkit, capable of representing WDs across a digital experimental environment. Global sensitivity testing was conducted using the Morris method (Morris, 1991) to assess the sensitivity of five aspects of the toolkit, and their potentially influences on geomorphology and flood risk reduction.</p>

An initial assessment of bed destabilization risk past vegetation patches using instrumented particles

2021 ◽  
Author(s):  
Yi Xu ◽  
Valyrakis Manousos ◽  
Panagiotis Michalis
Keyword(s):  
Initial Assessment ◽  
Flow Structures ◽  
Clear Water ◽  
Flow Conditions ◽  
Flow Parameters ◽  
Water Conditions ◽  
The Mean ◽  
Acoustic Doppler Velocimetry ◽  
Patch Density ◽  
Vegetation Patches

<p>Instream vegetation may alter the mean and turbukent flow fields leading to destabilizing riverbed surface, under certain flow conditions. In particular, recent research on instream vegetation hydrodynamics and ecohydrogeomorphology has focused on how energetic flow structures and bulk flow parameters downstream a vegetation may result in riverbed destabilization. This study, demonstrated the application of a 20mm novel instrumented particle in recording entrainment rates downstream simulated vegetation patches of distinct densities, at various distances downstream these. A patch of 6mm acrilic cylinders is used to simulate the emergent vegetation having the same diameter (12cm) and different porosities or densities (void volume equal to 1.25%, 3.15%, 6.25%, 11.25%, and 17.25%). The flow velocity near the instrumented particle is recorded using acoustic Doppler velocimetry (ADV) with appropriate seeding, under clear water conditions. Preliminary results are presented with focus on the effect of vegetation patch density on the flow field and subsequent effects on particle entrainment rates and implications for bed surface destabilisation.</p>

scholarly journals Experimental investigation and multi-conditions identification method of centrifugal pump using Fisher discriminant ratio and support vector machine

2019 ◽  
Vol 11 (9) ◽  
pp. 168781401987804
Author(s):  
Guangqi Qiu ◽  
Si Huang ◽  
Yingkui Gu
Keyword(s):  
Support Vector Machine ◽  
Principal Component ◽  
Domain Analysis ◽  
Test System ◽  
Support Vector ◽  
Centrifugal Pumps ◽  
Flow Conditions ◽  
Identification Method ◽  
Fisher Discriminant ◽  
Time Flow

For identifying the operation situations of centrifugal pumps by artificial intelligence, we performed an experiment on multi-flow conditions. The multi-flow conditions were simulated by adjusting an automatic flow-regulating valve installed on outlet pipe, and the vertical vibration signals of 20 flow points at the bearing house were collected by the test system. By time-domain analysis, frequency-domain analysis, information entropy, empirical modal decomposition, and wavelet packet decomposition methods, a comprehensive feature space was constructed. In addition, the optimal features were selected by Fisher discriminant ratio, and the dimensionality of the selected optimal features was reduced with principal component analysis. Finally, support vector machine algorithm was employed to identify the real-time flow condition, and the hyper-parameters of support vector machine classifier model were optimized by a grid search technique. Results show that the vibration test can effectively simulate the operation situation of centrifugal pumps under multi-flow conditions, and the proposed multi-flow conditions identification method has achieved a good identification performance.

scholarly journals Three-Dimensional Analysis of Flow Velocities through a Large Pool Fish Pass in the Trzebuńka Stream

Proceedings ◽  
2019 ◽  
Vol 16 (1) ◽  
pp. 59
Author(s):  
Kamil Suder ◽  
Karol Plesiński ◽  
Artur Radecki-Pawlik
Keyword(s):  
Three Dimensional ◽  
Fish Passage ◽  
Point Of View ◽  
Shear Stresses ◽  
Velocity Measurements ◽  
Water Flow Velocity ◽  
Hydrodynamic Parameters ◽  
Fish Pass ◽  
Large Pool ◽  
Parameter Values

This paper presents the hydrodynamic parameter values of a large pool fish pass joined with block ramps in the Trzebuńka stream. The aim of this work is to evaluate the large pool fish pass patency in terms of fish and to answer the question of whether fish migration upstream is possible. The assessment of hydrodynamic parameters was carried out on the basis of water flow velocity measurements using a flow tracker device and by calculating the following parameters: Water depth, shear stresses, and Froude’s and Reynold’s numbers. Velocity measurements were carried out in 23–30 hydrometric points which were determined in each of the pools. A survey was done using the Topcon GTS-226 (Topcon Corporation, Tokyo, Japan) total station. The data were processed in order to obtain the results of hydrodynamic parameters prevailing in flowing water. The graphs were prepared using the Grapher 11 software, showing the distribution of individual hydrodynamic parameters for fish pass chambers and overflows in the fish passage. We concluded that the fish pass in Stróża was designed and constructed correctly. However, from a technical point of view, some deficiencies could be found.

Avoidance of Nonanadromous Fish Passage Impedance Caused by Highway Culverts

1996 ◽  
Vol 1559 (1) ◽  
pp. 34-41
Author(s):  
G. Michael Fitch
Keyword(s):  
Flow Velocity ◽  
Fish Passage ◽  
Hydraulic Efficiency ◽  
Normal Flow ◽  
Flow Conditions ◽  
Term Survival ◽  
Wild Trout ◽  
Trout Streams ◽  
Water Depths

Highway culverts may hinder the normal migrations of various trout species in wild trout streams through increased flow velocity, shallow water depths, increased turbulence, and perching. This can impede migrational movements, affecting the genetic diversity and long-term survival of some species. Often, the proper installation of culverts can reduce the adverse effects on fish while maintaining hydraulic efficiency. This study characterized the problems with existing culverts to develop guidelines for the future use of culverts in areas with high gradient streams. Installation criteria will ideally limit the use of bridges where culverts are appropriate, and eliminate the use of culverts where they would create fish passage problems. This will reduce installation, maintenance, and retrofitting costs. The study concluded that culverts can be considered the primary option for crossing trout streams if the culvert can be placed on the same slope as that of the streambed, the slope of the stream is less than 3 percent, the flow velocity does not exceed 1.2 m/sec under normal flow conditions, and the barrel of the culvert can be properly countersunk at the outlet to prevent perching. Bridges should be used at these crossings if any of these criteria cannot be met. The study also concluded that baffles should not be used to control streamflow velocities in newly installed culverts, and concrete aprons should not be used at culvert outlets.

Numerical Simulations of Flow in Cerebral Aneurysms: Comparison of CFD Results and In Vivo MRI Measurements

2008 ◽  
Vol 130 (5) ◽  
Author(s):  
Vitaliy L. Rayz ◽  
Loic Boussel ◽  
Gabriel Acevedo-Bolton ◽  
Alastair J. Martin ◽  
William L. Young ◽  
...  
Keyword(s):  
Flow Fields ◽  
Patient Specific ◽  
Flow Ratio ◽  
Flow Conditions ◽  
Velocity Measurements ◽  
Cfd Simulations ◽  
Specific Flow ◽  
Inlet Flow ◽  
Good Agreement

Computational fluid dynamics (CFD) methods can be used to compute the velocity field in patient-specific vascular geometries for pulsatile physiological flow. Those simulations require geometric and hemodynamic boundary values. The purpose of this study is to demonstrate that CFD models constructed from patient-specific magnetic resonance (MR) angiography and velocimetry data predict flow fields that are in good agreement with in vivo measurements and therefore can provide valuable information for clinicians. The effect of the inlet flow rate conditions on calculated velocity fields was investigated. We assessed the internal consistency of our approach by comparing CFD predictions of the in-plane velocity field to the corresponding in vivo MR velocimetry measurements. Patient-specific surface models of four basilar artery aneurysms were constructed from contrast-enhanced MR angiography data. CFD simulations were carried out in those models using patient-specific flow conditions extracted from MR velocity measurements of flow in the inlet vessels. The simulation results computed for slices through the vasculature of interest were compared with in-plane velocity measurements acquired with phase-contrast MR imaging in vivo. The sensitivity of the flow fields to inlet flow ratio variations was assessed by simulating five different inlet flow scenarios for each of the basilar aneurysm models. In the majority of cases, altering the inlet flow ratio caused major changes in the flow fields predicted in the aneurysm. A good agreement was found between the flow fields measured in vivo using the in-plane MR velocimetry technique and those predicted with CFD simulations. The study serves to demonstrate the consistency and reliability of both MR imaging and numerical modeling methods. The results demonstrate the clinical relevance of computational models and suggest that realistic patient-specific flow conditions are required for numerical simulations of the flow in aneurysmal blood vessels.

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