Water velocity regulates macro‐consumer herbivory on the benthic macrophyte Podostemum ceratophyllum Michx.

2019 ◽  
Vol 64 (11) ◽  
pp. 2037-2045
Author(s):  
James L. Wood ◽  
Jon W. Skaggs ◽  
Caitlin Conn ◽  
Mary C. Freeman
Keyword(s):  
Water Velocity ◽  
Podostemum Ceratophyllum

Post-Hurricane Michael damage assessment using ADCIRC storm surge hindcast, image classification, and LiDAR

Shore & Beach ◽  
2019 ◽  
pp. 3-14 ◽  
Author(s):  
Joshua Davis ◽  
Diana Mitsova ◽  
Tynon Briggs ◽  
Tiffany Briggs
Keyword(s):  
Wave Energy ◽  
Field Studies ◽  
Feedback Mechanism ◽  
Water Velocity ◽  
Airborne Lidar ◽  
Storm Events ◽  
Magnetic Current ◽  
Coastal Mapping ◽  
Electro Magnetic

Wave forcing from hurricanes, nor’easters, and energetic storms can cause erosion of the berm and beach face resulting in increased vulnerability of dunes and coastal infrastructure. LIDAR or other surveying techniques have quantified post-event morphology, but there is a lack of in situ hydrodynamic and morphodynamic measurements during extreme storm events. Two field studies were conducted in March 2018 and April 2019 at Bethany Beach, Delaware, where in situ hydrodynamic and morphodynamic measurements were made during a nor’easter (Nor’easter Riley) and an energetic storm (Easter Eve Storm). An array of sensors to measure water velocity, water depth, water elevation and bed elevation were mounted to scaffold pipes and deployed in a single cross-shore transect. Water velocity was measured using an electro-magnetic current meter while water and bed elevations were measured using an acoustic distance meter along with an algorithm to differentiate between the water and bed during swash processes. GPS profiles of the beach face were measured during every day-time low tide throughout the storm events. Both accretion and erosion were measured at different cross-shore positions and at different times during the storm events. Morphodynamic change along the back-beach was found to be related to berm erosion, suggesting an important morphologic feedback mechanism. Accumulated wave energy and wave energy flux per unit area between Nor’easter Riley and a recent mid-Atlantic hurricane (Hurricane Dorian) were calculated and compared. Coastal Observations: JALBTCX/NCMP emergency-response airborne Lidar coastal mapping & quick response data products for 2016/2017/2018 hurricane impact assessments

scholarly journals Monitoring Lakes Surface Water Velocity with SAR: A Feasibility Study on Lake Garda, Italy

2021 ◽  
Vol 13 (12) ◽  
pp. 2293
Author(s):  
Marina Amadori ◽  
Virginia Zamparelli ◽  
Giacomo De Carolis ◽  
Gianfranco Fornaro ◽  
Marco Toffolon ◽  
...  
Keyword(s):  
Surface Water ◽  
Wind Waves ◽  
Test Site ◽  
Water Velocity ◽  
Surface Velocity ◽  
Medium Size ◽  
Small Scale ◽  
Lake Garda ◽  
Marine Applications

The SAR Doppler frequencies are directly related to the motion of the scatterers in the illuminated area and have already been used in marine applications to monitor moving water surfaces. Here we investigate the possibility of retrieving surface water velocity from SAR Doppler analysis in medium-size lakes. ENVISAT images of the test site (Lake Garda) are processed and the Doppler Centroid Anomaly technique is adopted. The resulting surface velocity maps are compared with the outputs of a hydrodynamic model specifically validated for the case study. Thermal images from MODIS Terra are used in support of the modeling results. The surface velocity retrieved from SAR is found to overestimate the numerical results and the existence of a bias is investigated. In marine applications, such bias is traditionally removed through Geophysical Model Functions (GMFs) by ascribing it to a fully developed wind waves spectrum. We found that such an assumption is not supported in our case study, due to the small-scale variations of topography and wind. The role of wind intensity and duration on the results from SAR is evaluated, and the inclusion of lake bathymetry and the SAR backscatter gradient is recommended for the future development of GMFs suitable for lake environments.

scholarly journals Assessment of Steady and Unsteady Friction Models in the Draining Processes of Hydraulic Installations

Water ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 1888
Author(s):  
Óscar E. Coronado-Hernández ◽  
Ivan Derpich ◽  
Vicente S. Fuertes-Miquel ◽  
Jairo R. Coronado-Hernández ◽  
Gustavo Gatica
Keyword(s):  
Mathematical Model ◽  
Turbulent Flow ◽  
Water Velocity ◽  
Experimental Facility ◽  
Governing Equations ◽  
Pressure Oscillations ◽  
Air Pocket ◽  
Friction Models ◽  
The Mathematical Model

The study of draining processes without admitting air has been conducted using only steady friction formulations in the implementation of governing equations. However, this hydraulic event involves transitions from laminar to turbulent flow, and vice versa, because of the changes in water velocity. In this sense, this research improves the current mathematical model considering unsteady friction models. An experimental facility composed by a 4.36 m long methacrylate pipe was configured, and measurements of air pocket pressure oscillations were recorded. The mathematical model was performed using steady and unsteady friction models. Comparisons between measured and computed air pocket pressure patterns indicated that unsteady friction models slightly improve the results compared to steady friction models.

The effect of water velocity on feeding efficiency of juvenile Chinese sturgeon, Acipenser sinensis

2017 ◽  
Vol 34 (1) ◽  
pp. 29-32 ◽  
Author(s):  
X. L. Gu ◽  
F. Zhao ◽  
P. Zhuang ◽  
X. T. Shi ◽  
G. P. Feng ◽  
...  
Keyword(s):  
Water Velocity ◽  
Chinese Sturgeon ◽  
Acipenser Sinensis ◽  
Effect Of Water ◽  
Feeding Efficiency

Is it possible to predict habitat use by spawning salmonids? A test using California golden trout (Oncorhynchus mykiss aguabonita)

1999 ◽  
Vol 56 (9) ◽  
pp. 1576-1584 ◽  
Author(s):  
Roland A Knapp ◽  
Haiganoush K Preisler
Keyword(s):  
Oncorhynchus Mykiss ◽  
Water Depth ◽  
Parametric Model ◽  
Water Velocity ◽  
Habitat Characteristics ◽  
Nonparametric Model ◽  
Habitat Features ◽  
Substrate Size ◽  
Depth Water ◽  
Spawning Sites

It is widely believed that stream salmonids select spawning sites based on water depth, water velocity, and substrate size. Attempts to predict spawning locations using these habitat features have met with little success, however. In this study, we used nonparametric logistic regression to determine what habitat features were associated with the locations chosen by spawning California golden trout (Oncorhynchus mykiss aguabonita). From this nonparametric model, we developed a parametric model that incorporated the habitat features most strongly associated with spawning sites and used this model to calculate the probability of use by spawning golden trout for specific stream locations. The overall nonparametric model was highly significant and explained 62% of the variation in spawning location. Four of the eight habitat variables, substrate size, water depth, water velocity, and stream width, had highly significant effects and alone explained 59% of the variation in spawning location. The results of a cross-validation procedure indicated that the parametric model generally provided a good fit to the data. These results indicate that location-specific probabilities of use were predictable based on easily measured habitat characteristics and that nonparametric regression, an approach still rarely used in ecological studies, may have considerable utility in the development of fish-habitat models. Given the escalating pace at which fish habitats are being altered, such models are increasingly important in predicting the effects of these alterations on populations.

Spatial distribution of macrozoobenthos communities in a plain river of a semi-desert zone

2021 ◽  
pp. 131-150
Author(s):  
Larisa V. Golovatyuk ◽  
◽  
Roman A. Mikhailov ◽  
◽  
Keyword(s):  
Spatial Distribution ◽  
Statistical Analysis ◽  
Surface Area ◽  
Patch Dynamics ◽  
Water Velocity ◽  
River Network ◽  
Russian Plain ◽  
The Family ◽  
Functional Process ◽  
Desert Zone

Current climate changes require special attention to the implementation of environmental activities in arid regions. The study of the biotic component of water bodies of such ecosystems and the patterns of their spatial distribution is an important area of scientific research. The river network of the semi-desert zone of the Russian Plain is one of the least studied lotic systems in the Lower Volga basin. In this river network, the plain Yeruslan River is of the greatest importance because it largely determines the environmental characteristics of this arid territory. Therefore, it is important to study the structural indicators and spatial dynamics of macrozoobenthos communities in the Yeruslan River. The aim of the work was to study species composition, the structural and quantitative indicators of macrozoobenthos from the source to the mouth of the Yeruslan River and to determine the conceptual belonging of the bottom communities of the plain river of the semidesert zone to a certain type of distribution. The Yeruslan River (51°18'3''N, 47°46'19''E) flows through the semi-desert zone of the Russian Plain (Volgograd region, Russia) and it is a tributary of Volgograd reservoir. The length of the Yeruslan River is 282 km, with a catchment area of 55700 km2. We collected samples of macrozoobenthos at 9 stations of the Yeruslan River (See Fig. 1) in June 2015 and July 2016. In the ripal zone, the integrated samples for quantitative macrozoobenthos analysis were taken using an Ekman-type grab sampler (surface area 25 cm2) in replicates (8X) and a handle blade trawl (0.2 м × 0.5 м). In the medial zone, samples were taken by an Ekman-type grab sampler (surface area 250 cm2) in replicates (2X). Samples were washed in the field using a mesh screen with 300-310-μm mesh size and preserved in 4% formaldehyde. At each station of the Yeruslan River, we used field analytical instruments for measuring pH and oxygen content. Water samples were taken for hydrochemical analysis at different sections of the river (See Table 1). We used the model of isolation by distance (Malécot, 1948), Monmonier’s maximum difference algorithm (Manni et al., 2004) and the Dickey-Fuller test (Dickey and Fuller, 1979) to perform statistical analysis of changes in the species structure of macrozoobenthos. The Yeruslan River flows within the geochemical province of continental salinity, which is characterized by an evaporative type of natural water regime, leading to progressive accumulation of salts. In this research, we found out that water was brackish at several stations of the river (1250-1420 mgl-1) due to water drainage of saline soils. We revealed that the Yeruslan River is polluted with nitrite nitrogen (at station 1) and phosphorus compounds (at stations 4 and 8) but concentrations of ammonium nitrogen, nitrate nitrogen, cadmium, copper, zinc and lead did not exceed the MPC. Comparative analysis has shown that from the source to the mouth of the river there are no significant changes in the speed of water velocity flow, and the physical and chemical conditions are specific for each station. In the river, we collected 132 species: 47 - Diptera, 20 - Oligochaeta, 11 - Mollusca, 11 - Grustacea, 11 - Coleoptera, 7 - Trichoptera, 7 - Heteroptera, 6 - Hirudinea, 4 - Odonata, 4 - Ephemeroptera, 1 - Lepidoptera, Hydracarina, Polychaeta and Megaloptera. The macrozoobenthos of the river is represented by limnophilic species in the upper, middle and lower reaches. This is due to the small slope of the Yeruslan River and the presence of permanent and temporary dams. In the mouth reaches, the macrozoobenthos communities included species of the Ponto-Caspian and Ponto-Azov zoogeographic complexes. At all stations of the river, Oligochaeta and Chironomidae were of high density. Also, in the river mouth, Mollusca were of high density (See Fig. 2). Statistical analysis of sequences of hydrobiological characteristics along the longitudinal gradient of the Yeruslan River using the Dickey- Fuller test showed that the presence of a stationary distribution trend with random “wandering” is typical of the series of total density and biomass of macrozoobenthos, the number of worms of the family Tubificidae, larvae of chironomids of the subfamily Tanytarsini and mayflies of the family Baetidae. For the other series of observations, the presence of a nonlinear trend is noted (See Table 3 and Fig. 3). The selection of a sequence of borders (barrier) between river communities within the ecosystem by Montmonier’s method using a matrix of species distances by the Bray-Curtis method made it possible to identify the source (station 1) with a high level of nitritic nitrogen in the water as one of the specific areas. The second most important border separates station 3 with a low content of dissolved oxygen, and the third one allocates the mouth reaches (station 9) as an independent area, where there is a cohabitation of river and reservoir species (See Fig. 4). Based on the analysis of fauna and using statistical methods, we found out that macrozoobenthos communities do not change from the source to the mouth of the river in accordance with the “the river continuum concept”. The habitat of taxa depends on local abiotic and biotic factors at each river station, therefore, we can assume that the distribution of macrozoobenthos communities, generally, corresponds to “the patch dynamics concept”. At the same time, stations 1, 3 and 9 form fairly isolated hydrogeomorphological areas, which is postulated by the concept of “the functional process zones”. It seems that the spatial distribution of macrozoobenthos communities in the Yeruslan River can be explained by a complex combination of two concepts: “the patch dynamics concept” and “the functional process zones”. This type of distribution seems to be typical of plain rivers with very low water velocity and the presence of dams.

scholarly journals Depth-Average Velocity from Spray Underwater Gliders

2018 ◽  
Vol 35 (8) ◽  
pp. 1665-1673 ◽  
Author(s):  
Daniel L. Rudnick ◽  
Jeffrey T. Sherman ◽  
Alexander P. Wu
Keyword(s):  
Average Velocity ◽  
Dead Reckoning ◽  
Water Velocity ◽  
Accurate Estimation ◽  
Underwater Glider ◽  
Underwater Gliders ◽  
Before And After ◽  
The Difference ◽  
Using Data ◽  
Acoustic Doppler Current Profilers

AbstractThe depth-average velocity is routinely calculated using data from underwater gliders. The calculation is a dead reckoning, where the difference between the glider’s velocity over ground and its velocity through water yields the water velocity averaged over the glider’s dive path. Given the accuracy of global positioning system navigation and the typical 3–6-h dive cycle, the accuracy of the depth-average velocity is overwhelmingly dependent on the accurate estimation of the glider’s velocity through water. The calculation of glider velocity through water for the Spray underwater glider is described. The accuracy of this calculation is addressed using a method similar to that used with shipboard acoustic Doppler current profilers, where water velocity is compared before and after turns to determine a gain to apply to glider velocity through water. Differences of this gain from an ideal value of one are used to evaluate accuracy. Sustained glider observations of several years off California and Palau consisted of missions involving repeated straight sections, producing hundreds of turns. The root-mean-square accuracy of depth-average velocity is estimated to be in the range of 0.01–0.02 m s−1, consistent with inferences from the early days of underwater glider design.

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