A Review of Particle Image Velocimetry for Fish Migration

Understanding the flow characteristic in fishways is crucial for efficient fish migration. Flow characteristic measurements can generally provide quantitative information of velocity distributions in such passages;Particle Image Velocimetry (PIV) has become one of the most versatile techniques to disclose flow fields in general and in fishways, in particular. This paper firstly gives an overview of fish migration along with fish ladders and then the application of PIV measurements on the fish migration process. The overview shows that the quantitative and detailed turbulent flow information in fish ladders obtained by PIV is critical for analyzing turbulent properties and validating numerical results.

Numerical Investigation of Turbulent Flow through Rectangular and Biconvex Shaped Trash Racks

Turbulent flow through a trash rack of bars of rectangular and biconvex shapes is considered. A trash rack is composed of an array of bars fitted into a hydro-electric power station to prevent debris and fish to enter the waterway towards the turbine. The work is directed towards modeling a large number of bars for which the flow turn out to have a periodic structure. It is here shown that this case can be simplified with the flow past a single bar together with periodic boundary conditions. Using this approach the head loss is derived for different angles of attack α and blockages P for two shapes of the rack, a rectangular bar and an aerodynamically shaped biconvex bar. It is found that overall loss of the biconvex bars is in general about 15% of the loss for the rectangular case for small angles of attack. For large angle of attack this difference diminishes. Of interest for the biconvex bars is also a local minimum in the head loss for angles approximately greater than 20°and for a blockage P around 0.35. This combination of parameters gives a low loss together with an efficient barrier for debris and fishes.

Biological exposure models for oil spill impact analysis

The oil spill impact analysis (OSIA) software system has been developed to supply a tool for comprehensive, quantitative environmental impact assessments resulting from oil spills. In the system, a biological component evaluates potential effects on exposed organisms based on results from a physico chemical fates component, including the extent and characteristics of the surface slick, and dissolved and total concentrations of hydrocarbons in the water column. The component includes a particle based exposure model for migratory adult fish populations, a particle based exposure model for spawning planktonic organisms (eggs and larvae), and an exposure model for wildlife species (sea birds or marine mammals). The exposure model for migratory adult fish populations simulates the migration behaviors of fish populations migrating to or staying in their feeding areas, over wintering areas or spawning areas, and determines the acute effects (mortality) and chronic accumulation (body burdens) from the dissolved contaminant. The exposure model for spawning planktonic organisms simulates the release of eggs and larvae, also as particles, from specific spawning areas during the spawning period, and determines their potential exposure to contaminants in the water or sediment. The exposure model for wild species calculates the exposure to surface oil of wildlife (bird and marine mammal) categories inhabiting the contaminated area. Compared with the earlier models in which all kinds of organisms are assumed evenly and randomly distributed, the updated biological exposure models can more realistically estimate potential effects on marine ecological system from oil spill pollution events.

A potential engineering solution to facilitate upstream movement of fish in mountain rivers with weirs:Southern Carpathians,the Azuga River

An important aspect in the restoration of longitudinal connectivity in rivers and streams is the implementation of fish migration systems at the upstream of the functional hydraulic structures(weirs,drop structures or river sills).The diversity of these existing structures as well as the different locations of these weirs within the river,watershed and riparian zone challenge the design engineers to find new holistic solutions for fish migration systems.The Azuga River study area requires a new synergistic fish migration design system.Being a mountain area,rapid increase in water level is quite frequent,especially after heavy or prolonged rainfalls and during spring snow melt.Therefore,it is necessary to design a specific system for fish migration to meet this location’s requirements.Due to the characteristics in this location of the Azuga river,the classic fish migration systems would not be functional.The indigenous/mountain trout is considered as the target species in this paper.Although this is a good swimming species,the use of classical systems could,due to exhaustion,prevent and/or reduce the movement of fish upstream of the two weirs(also known as river sills).This new,comprehensive solution,presented in this paper includes:(i)the restoration and stabilization works of the right bank in the weir study area by using biotechnical measures and(ii)the upstream migration system itself-for supporting the migration of fish on the Azuga River.

Evaluation of cone fishways to facilitate passage of small-bodied fish

Fishways are being provided more regularly than ever before and new designs are needed to provide passage for whole fish communities.Despite recent progress,fishways have frequently performed poorly,especially for small-bodied fish(i.e.10-100 mm long),which can form large aggregations below stream barriers.This was the genesis for the development of the cone fishway design,a new style of technical fishway which consists of a series of pre-fabricated cone-shaped concrete baffles installed laterally within a concrete channel.The cone design arose from the need to install rock ramp fishways at remote sites where rock was unavailable and where maintenance would be infrequent.The objective of the present study was to evaluate the suitability of the new cone fishway design to provide passage for small-bodied diadromous species(i.e.<100 mm long).Cone fishways were evaluated at three low head(e.g.<3 m high)case-study sites in tropical and temperate Australia and in total,45 species and 28,556 fish were collected.There was passage of a broad range of the target size-classes of small-bodied fish and individuals as small as nine mm could ascend.However,further work is needed to quantify the proportion of the small-bodied fish population in the river downstream which find and pass through the cone fishways.The most suitable experimental application of the cone fishway is at sites where there is:(i)a narrow(e.g.<0.4 m)headwater range,and(ii)where passage of small-bodied fish is a major ecological priority.Cone fishways provide a useful and novel option to improve passage of small-bodied fish,at appropriate sites,and contribute to a contemporary vision of restoration of whole fish communities.