scholarly journals Responses of four submerged macrophytes to freshwater snail density ( Radix swinhoei ) under clear‐water conditions: A mesocosm study

2020 ◽  
Vol 10 (14) ◽  
pp. 7644-7653
Author(s):  
Yongwei Zhi ◽  
Yang Liu ◽  
Wei Li ◽  
Yu Cao
Keyword(s):  
Submerged Macrophytes ◽  
Freshwater Snail ◽  
Clear Water ◽  
Snail Density ◽  
Water Conditions

Riprap Performance at Bridge Piers Under Mobile-Bed Conditions

1998 ◽  
Vol 1647 (1) ◽  
pp. 27-33 ◽  
Author(s):  
Carlos Toro-Escobar ◽  
Richard Voigt ◽  
Bruce Melville ◽  
Meng Chiew ◽  
Gary Parker
Keyword(s):  
Experimental Tests ◽  
Bridge Piers ◽  
Design Criteria ◽  
Research Groups ◽  
Clear Water ◽  
Pier Scour ◽  
Mobile Bed ◽  
Water Conditions ◽  
Improved Design ◽  
Flood Flow

Design criteria for riprap at bridge piers in rivers is based on the specification of a size, gradation, and cover that does not fail under an appropriately chosen flood flow. Experimental tests of riprap performance at bridge piers to date have relied on a configuration for which the ambient bed is not mobilized, that is, clear-water conditions. In the field, however, riprap is, as a rule, subjected to mobile-bed conditions during floods. Recent experiments by three cooperating research groups (University of Auckland, Nanyang University, and St. Anthony Falls Laboratory) indicate a heretofore unrecognized mechanism for riprap failure under mobile-bed conditions. When the flow is in the dune regime, the passage of successive dunes causes riprap that is never directly entrained by the flow to sink and disperse. Pier scour is realized as a consequence of these processes. In some cases, the depth of scour realized is not significantly less than that which would occur without riprap. When the riprap is fully underlain by a geotextile, edge effects can cause local removal of riprap, upturning of the geotextile, and general failure. When the riprap is underlain by a partial geotextile (i.e., one that covers an area less than the riprap), edge scour causes local sinking that anchors the geotextile. The sinking and dispersion of the rest of the riprap are greatly limited, and the riprap fails only when flow velocities are sufficient for direct entrainment. The experiments suggest improved design criteria for the installation of riprap in the field.

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>

Kinetics of bacteria inactivation employing UV radiation under clear water conditions

2006 ◽  
Vol 121 (2-3) ◽  
pp. 135-145 ◽  
Author(s):  
M LABAS ◽  
R BRANDI ◽  
C MARTIN ◽  
A CASSANO
Keyword(s):  
Uv Radiation ◽  
Clear Water ◽  
Bacteria Inactivation ◽  
Water Conditions ◽  
Kinetics Of

Conception et performance d'un champ d'épandage de grandes dimensions

1988 ◽  
Vol 15 (2) ◽  
pp. 216-222 ◽  
Author(s):  
Robert P. Chapuis
Keyword(s):  
Service Life ◽  
Ground Water ◽  
Infiltration Rate ◽  
Full Scale ◽  
Full Scale Test ◽  
Clear Water ◽  
Good Design ◽  
Water Conditions ◽  
Evaporation Losses ◽  
Scale Test

A large disposal field (31 × 69 m) was designed in agreement with legal recommendations. A full scale test with clear water revealed that the field exfiltration rate was much lower than anticipated. This paper describes the design, the instrumentation performed with eleven piezometers, the ground-water conditions as modified by the disposal field, how the true exfiltration rates have been determined after due consideration of natural precipitations and evaporation losses, and also the method used to improve the performance. The value of the infiltration rate into the soil, initially established by percolation tests, was confirmed by permeability tests performed in the piezometers. However, the true exfiltration rate of this disposal field was only 8% of the rate predicted by the conventional, legal design. It is established that this exfiltration rate cannot be derived by simple transposition of the results of percolation tests as presently done by by-laws. Alternatively, more rigorous methods are described. For a good design, it is necessary to perform hydrogeologic studies much more detailed than those presently required by by-laws. Finally, for improving the design and service life of such disposal fields, several suggestions are made to avoid water mounds and to reduce the risk of clogging.

scholarly journals The effect of tetrahedron framed permeable weirs on river bed stability in a mountainous area under clear water conditions

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Jia-mei Wang ◽  
Xing-guo Yang ◽  
Hong-wei Zhou ◽  
Zi-hao Wang ◽  
Jia-wen Zhou ◽  
...  
Keyword(s):  
Mountainous Area ◽  
Clear Water ◽  
River Bed ◽  
Water Conditions ◽  
Bed Stability

scholarly journals Water turbidity constrains male mating success in a marine fish

2019 ◽  
Vol 73 (10) ◽  
Author(s):  
Marja Järvenpää ◽  
Beatriz Diaz Pauli ◽  
Kai Lindström
Keyword(s):  
Mating Success ◽  
Aquatic Systems ◽  
Male Mating ◽  
Female Size ◽  
Turbid Water ◽  
Male Mating Success ◽  
Clear Water ◽  
Sand Goby ◽  
Water Turbidity ◽  
Water Conditions

Abstract Human-induced eutrophication, resulting in increased algal growth and water turbidity, is an alarming problem in aquatic systems. Many studies have focused on the effects of algal turbidity on mate choice and sexual selection in fish, but little emphasis has been given to the ways it can constrain mating success. Here we experimentally investigated the effects of algal turbidity on maximum male mating success and parental care in the sand goby, Pomatoschistus minutus, a fish with a resource-defence mating system and male parental care. For this purpose, we introduced to 1 nest-holding male 5 random-sized ripe females in either clear or in turbid water. After spawning, we observed how many mates and eggs the male received and followed his parental behaviour and egg survival for 6 days under turbid or clear water conditions. When spawning took place in clear water, the number of eggs the male received into his nest increased with the total weight of five females in his tank. However, when spawning took place in turbid water, there was no relationship between female size and the number of eggs laid, although the number of females that spawned was the same as in clear water. The results indicate that females adjust the number of eggs they lay according to water turbidity. This could explain previous findings that mating success is more evenly distributed among males in turbid than clear water conditions. Significance statement The first responses of animals to human-induced changes in the environment are behavioural. Subtle changes in the behaviour of individuals can have profound consequences for populations and communities. Human-induced eutrophication, leading to algal blooms and water turbidity, is a major environmental problem in aquatic systems worldwide. Our results on the sand goby suggest a new mechanism by which water turbidity may affect fish mating systems and weaken sexual selection. When spawning takes place in clear water, the number of eggs accumulated in a males’ nest is an increasing function of the fecundity of the females. However, when spawning in turbid water, this positive relationship between female size and egg numbers disappears. We believe this is because females do not perceive the competition from other females in turbid water and therefore invest less in present reproduction.

Sign in / Sign up

Export Citation Format

Share Document