Search results for "Water"
showing 10 items of 9348 documents
Sedimentology and vertebrate fossils of the Frasnian Ogre Formation, Gurova outcrops, eastern Latvia
2020
Combined sedimentological and palaeontological study of the siliciclastic sequence of the Ogre Formation in the easternmost area of its distribution in Latvia was aimed at the facies analysis of the deposits and at detailed observation of the taxonomical and taphonomical peculiarities of the fossil vertebrate assemblage. Two facies associations, tidally-influenced fluvial channels and lateral tidal bars, have been identified in exposures along the Gurova River. Sedimentological evidences suggest that the studied deposits were formed in the fluvial environment with strong tidal influence. The sedimentary concentrations of vertebrate remains, dominated by the antiarch Bothriolepis maxima, por…
Influence of bed roughness on flow and turbulence structure around a partially-buried, isolated freshwater mussel
2023
The present study uses eddy-resolving numerical simulations to investigate how bed roughness affects flow and turbulence structure around an isolated, partially-buried mussel (Unio elongatulus) aligned with the incoming flow. The rough-bed simulations resolve the flow past the exposed part of a gravel bed, whose surface is obtained from a laboratory experiment that also provides some additional data for validation of the numerical model. Results are also discussed for the limiting case of a horizontal smooth bed. Additionally, the effects of varying the level of burial of the mussel inside the substrate and the discharge through the two mussel siphons are investigated via a set of simulatio…
Comparison between the MHFEM formulation and a 2nd spatial order FV formulation of the linear groundwater flow problem
2008
Mixed and Mixed Hybrid Finite Elements (MHFE) methods have been widely used in the last decade for simulation of groundwater flow problem, petroleum reservoir problems, potential flow problems, etc. The main advantage of these methods is that, unlike the classical Galerkin approach, they guarantee local and global mass balance, as well the flux continuity between inter-element sides. The simple shape of the control volume, where the mass conservation is satisfied, makes also easier to couple this technique with a Finite Volume technique in the time splitting approach for the solution of advection-dispersion problems. In the present paper a new second spatial approximation order Finite Volum…
Assessing Stress Resilience After Smolt Transportation by Waterborne Cortisol and Feeding Behavior in a Commercial Atlantic Salmon (Salmo salar) Grow…
2022
Sampling protocols and water quality sensors have been developed to assess fish health and welfare in recirculating aquaculture systems (RASs). Still, the use of fish-based non-invasive welfare indicators, reflecting the physiological state of the fish, is limited in this type of system. Cortisol, the major stress-coping hormone in fish, diffuses through the gills. Consequently, waterborne cortisol is a potential fish-based non-invasive welfare indicator in RAS. However, its use in commercial rearing systems is sparse. In this study, we evaluated water cortisol levels and feeding behavior as welfare indicators of newly inserted smolt in a commercial RAS for harvest size Atlantic salmon. The…
Upper Caraş River (Danube watershed) fish populations fragmentation – technical rehabilitation proposal
2017
Abstract We propose a technical solution for fish movement based on the flow of water over a spill threshold. Such barriers are common in the Danube system. The proposed system has a range of operating components which are easily detachable from the spill threshold, are resistant to corrosion and will not harm the fish. In fact, if designed to complement swimming abilities of target fish, it should provide adequate passage for both adults and juveniles. If implemented correctly, the design may offer a solution to help displaced fish recolonize upstream habitats.
The Role of Aquatic Refuge Habitats for Fish, and Threats in the Context of Climate Change and Human Impact, during Seasonal Hydrological Drought in …
2021
In spite of the obvious climate changes effects on the Carpathian Basin hydrographic nets fish fauna, studies on their potential refuge habitats in drought periods are scarce. Multiannual (2016–2021) research of fish in some streams located in the Saxon Villages area during hydrological drought periods identified, mapped, and revealed the refuge aquatic habitats presence, management needs, and importance for fish diversity and abundance for small rivers. The impact of increasing global temperature and other human activities induced hydrologic net and habitats alteration, decreased the refuge habitats needed by freshwater fish, diminished the fish abundance, and influenced the spatial and te…
Automated Plankton Classification With a Dynamic Optimization and Adaptation Cycle
2022
With recent advances in Machine Learning techniques based on Deep Neural Networks (DNNs), automated plankton image classification is becoming increasingly popular within the marine ecological sciences. Yet, while the most advanced methods can achieve human-level performance on the classification of everyday images, plankton image data possess properties that frequently require a final manual validation step. On the one hand, this is due to morphological properties manifesting in high intra-class and low inter-class variability, and, on the other hand is due to spatial-temporal changes in the composition and structure of the plankton community. Composition changes enforce a frequent updating…
Reproduction of Baltic cod, Gadus morhua (Actinopterygii: Gadiformes: Gadidae), in the Gotland Basin: Causes of annual variability
2015
Background. The Gotland Basin spawning ground is one of three main spawning areas of Baltic cod, Gadus morhua Linnaeus, 1758. The threshold water parameters for cod development are the salinity exceeding 11‰ and the oxygen level above 2 mL· L–1. Such conditions are only present when the 11‰ isohaline is above the 2 mL· L–1 isooxygen. In such situation the water volume between the isolines is called the “suitable reproduction volume”. When the position of the isolines is reversed, the salinity and the oxygen level of the water layer demarcated by them are below the required thresholds and as such the water is unsuitable for the cod development. We refer to it as the “unsuitable reproduction …
A cost efficiency analysis of flood proofing measures for hydraulic risk mitigation in an Urbanized riverine area
2020
Non-structural measures for flood risk mitigation are often more economically accessible, easier to implement, and are highly effective, especially in view of the pursuit of risk resilience objectives. Among the non-structural measures, more importance is increasingly being attributed to flood proofing interventions. There are two main types of flood proofing: dry proofing and wet proofing. An example of dry proofing is shielding, which involves the use of flood barriers that can be installed in the entrances of buildings or outside the buildings in order to avoid contact with the houses and deviate the water flow. Their use must be supported by a detailed hydraulic analysis to ensure the c…
The FLO Diffusive 1D-2D Model for Simulation of River Flooding
2016
An integrated 1D-2D model for the solution of the diffusive approximation of the shallow water equations, named FLO, is proposed in the present paper. Governing equations are solved using the MArching in Space and Time (MAST) approach. The 2D floodplain domain is discretized using a triangular mesh, and standard river sections are used for modeling 1D flow inside the section width occurring with low or standard discharges. 1D elements, inside the 1D domain, are quadrilaterals bounded by the trace of two consecutive sections and by the sides connecting their extreme points. The water level is assumed to vary linearly inside each quadrilateral along the flow direction, but to remain constant …