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Ecohydraulic flumes: are we taking full advantage of their potential for symmetrical interdisciplinary research?

Author(s): Paul S. Kemp; Christos Katopodis

Linked Author(s): Paul Kemp, Christos Katopodis

Keywords: No Keywords

Abstract: Leading-edge biological research is thriving and so does advanced research on hydraulics, aided by innovations in technology, instrumentation and respective conventional experimental facilities in laboratories or field stations. In long-established fields, such as ecology and biology or hydraulics, hydrology and geomorphology, state-of-the-art research may be self-sufficient in experimental facilities. In newer interdisciplinary fields, like ecohydraulics, the challenge of conducting cutting-edge research necessitates using innovations and advances in more than one field. In addition, experimental facilities, such as ecohydraulic flumes, are needed to allow studies, measurements and integration of biotic and abiotic variables under controlled conditions. The question then becomes what the appropriate balance between “eco” and “hydraulics” is for leading-edge ecohydraulic research. One may posit that research with ecohydraulic flumes is thriving, at least if the rapid growth of relevant publications is indicative. As ecohydraulic researchers though, we are aware that many studies involving ecohydraulic flumes struggle to balance “eco” with “hydraulics,” and only a limited number achieve suitable symmetry. It takes fully engaged interdisciplinary teams, using state-of-the-art technology, instrumentation, experimental facilities, analyses and integration of observations to reach ecohydraulic symmetry with interdisciplinarity as the overriding principle for all research aspects. How frequently does this actually happen? Ecohydraulic flumes, which have a water surface open to air pressure (as opposed to closed chambers with fluid pressure), facilitate research which integrates ecological/biological and hydraulic/morphodynamic aspects. Such flumes may be fixed or mobile, are used in laboratories or field stations, and are designed for the purpose of studying abilities and responses of aquatic flora and fauna to hydraulic/morphodynamic conditions in prototype to avoid scaling effects on biota and their behaviour (Katopodis 2005). Research on flora and fauna under controlled conditions in ecohydraulic flumes, contributes to improved understanding of the complex interactions between biota and hydraulic variables. Although in recent decades ecohydraulic flumes have been used for research on a variety of flora and fauna, different fish species have been the most common biota studied. The Fisheries-Engineering Research Laboratory adjacent to a fishway at Bonneville Dam was one of the first dedicated to ecohydraulic research on fish passage mostly for anadromous Pacific salmon relating to the hydroelectric generating stations on the Columbia River, USA (Collins and Elling 1960). Without fish tagging technology or videography, and simple hydrometric instruments, observations on fish behavioural responses and swimming performance were limited to average values of basic variables such as velocities, rates of fish movement, endurance times and swim distances. Aspects of fishway design and whether fish would utilize them were also tested. With the development of fish tagging technology, videography and more advanced hydrometric methods, opportunities to study finer scale fish movements, as well as associate them with detailed hydraulic variables, such as velocity distributions and various turbulence characteristics became accessible. Some of the earliest studies utilizing such developments in modernized ecohydraulic flumes were performed in Canada. Many studies in ecohydraulic flumes on a variety of fish species followed, notably at the S. O. Conte Anadromous Fish Research Center, Turners Falls, Massachusetts, USA, the International Centre for Ecohydraulics Research, University of Southampton, Southampton, UK, and the Hydraulics and Environment Department of the National Laboratory for Civil Engineering (LNEC), Lisbon, Portugal. Gradually ecohydraulic flumes became available as research tools in many countries and continue to expand around the globe. Numerous studies on flora and fauna are conducted worldwide, many times repeating similar investigations with different species, usually to provide information for environmental mitigation measures and practical applications. Less frequently, ecohydraulic flumes are used to innovate and pose scientific questions which facilitate discovery and enhance insight. Progress of course has been made over several years using ecohydraulic flumes with a variety of aquatic life forms studied under different hydrodynamic and morphodynamic conditions. Studies have been conducted on many aspects of the ecohydraulic trilogy: (1) movements, abilities and passage of aquatic organisms; (2) e-flows, i.e., environmental, ecological or instream flow regimes for aquatic flora and fauna; and (3) restoration of aquatic habitats and ecosystem morphodynamics. How often though in these studies do we take full advantage of the potential offered by ecohydraulic flumes which enable us to achieve leading-edge research? Using ecohydraulic flumes to combine state-of-the-art biology with basic hydraulics or vice versa, limits study design and allows inferences rather than direct observations in interpreting the results. More fully integrated ecohydraulic studies are still evolving with investigations of various aspects of turbulence and biota responses, striving for symmetry between ecological (or biological) and hydraulic variables. Flows in natural river systems and regulated waterways are turbulent, inherently three-dimensional, chaotic and random. Turbulence is dominated by coherent flow structures such as eddies, and these structures can significantly alter the hydraulic conditions and behavioural responses of aquatic biota and their habitats. Biota responses are affected by various characteristics of flow turbulence, such as turbulent intensity (TI), turbulent kinetic energy (TKE), turbulent dissipation rate (TDR), strain rate (SR), Reynolds shear stress (RSS), eddy size or rate of work (W). It is challenging to measure turbulent characteristics in 3-D and observe biota responses to such flow structures. Such challenges though inspire breakthroughs in instrumentation and research. For example, with recent developments in high-repetition rate lasers and high-speed cameras, high-resolution PIV methods such as time-resolved particle image velocimetry (TR-PIV), allow 3-D turbulent characteristics to be observed. Leading-edge and well integrated ecohydraulic research with symmetrical treatment of biota and hydraulics continues to overcome challenges, deserve more emphasis and may provide the best way forward. We would like to express our thanks and appreciation to the Associate and Guest Editors, as well as the conference organizers for the two Special Issues published in 2019. These are the first Special Issues for the Journal of Ecohydraulics and were the result of the efforts of the organizers to promote the journal at ISE2018 in Japan and FP2018 in Australia. We value the symbiotic relationship between the Journal of Ecohydraulics and these, as well as other conferences. We view such relationships as mutually beneficial, since conferences encourage authors to conduct and present high quality ecohydraulic studies, while we welcome such submissions for regular or special issues of TJoE. We offer special thanks to all reviewers for their comprehensive and diligent work, although we are unable to list them anymore. Our condolences and deepest sympathy to those who may have lost a loved one, colleague or friend in the COVID-19 pandemic. Stay safe and let’s ensure that the legacy of this new virus is the coming together and strengthening of the community to restore the International Symposia on Ecohydraulics, Fish Passage and other conferences, assemblies and meeting in the future. Perhaps this is an opportunity to spend some time writing and submitting manuscripts to the Journal of Ecohydraulics for a regular or special issue.


Year: 2020

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