Natural Fluvial Ecohydraulics

by

Gregory B. Pasternack

• LAST REVIEWED: 27 February 2019
• LAST MODIFIED: 27 February 2019
• DOI: 10.1093/obo/9780199363445-0111

Introduction

Ecohydraulics is the study of the mechanisms that explain hierarchically nested aquatic and riparian biotic phenomena. Mechanisms are sequential actions that can be physical, biological, or an interaction between the two. Biotic phenomena consist of individual, population, and community-level conditions, behaviors, and interactions. Hierarchical nesting means that phenomena are present across a wide range of spatial scales: from the smallest fluid continuum scale to the scale of the entire Earth. Many ecohydraulic studies prominently address scaling. Under this definitional framework and given the widespread occurrence of water on Earth, ecohydraulics is the “proximal” science mediating the influence of “distal” landscape drivers (e.g., climate, geology, and topography). Historically, scientists discovered empirical correlations relating biotic conditions to both proximal and distal abiotic variables. However, when such results are applied to practical societal problems (e.g., stream barrier passage, habitat rehabilitation, and flow regime specification), the accuracy and specificity is insufficient to solve them. That has led to widespread recognition of the need for a mechanistic understanding culminating in predictive numerical models. Driven by such necessity, physical and biological scientists and engineers have formed multidisciplinary teams to work out how water and biota interact. Through its marriage of conceptual understanding with quantitative analysis, ecohydraulics is playing a central role in methodological advancements to objectively, transparently, and repeatably explain biotic phenomena at multiple spatial scales. Students involved in ecohydraulics are part of an emerging interdisciplinary generation identifying more with problem-oriented applied science that responds to societal needs to solve specific ecological problems than disciplinarians driven by curiosity and traditional socio-scientific pathways. Nevertheless, it goes too far to conclude that ecohydraulics is nothing more than the application of other sciences, with no basic developments of its own. Necessity often motivates ecohydraulicists to undertake novel experiments revealing fundamental discoveries. As a result, a reasonable distinction can be made between basic ecohydraulics for studying natural phenomena and applied ecohydraulics for rehabilitating degraded phenomena. This annotated bibliography is the first of two spanning ecohydraulics, and it tackles the former, while the second addresses the latter. Due to space limitations, this article is narrowed to natural fluvial ecohydraulics. Within this domain, there are five essential topics: environmental fluid mechanics, flora ecohydraulics, fluvial habitat, faunal ecohydraulics, and fish migration. Finally, space limitations further limit the scope to an emphasis on observational studies over numerical modeling.

General Overviews

There are many compilations of articles in special volumes that address specific aspects of ecohydraulics. Similarly, since 1994 there have been biennial conference proceedings for the international symposia on ecohydraulics. Also, individual research groups have produced a variety of guidebooks that teach readers how to address specific environmental problems using ecohydraulics toolsets. However, when it comes to holistic general overviews about ecohydraulics as an emerging discipline, there are few places to turn. Statzner, et al. 1988 exemplifies the fact that people were doing ecohydraulics before the term existed, and they had the idea of a discipline centered on ecohydraulics. Also, that notion of ecohydraulics put the focus on mechanisms over correlations. Finally, Maddock, et al. 2013 is a comprehensive scope of literature reviews and new research spanning natural and applied ecohydraulics. It is likely that textbooks on ecohydraulics will be forthcoming soon.

• Maddock, I., A. Harby, P. Kemp, and P. Wood. 2013. Ecohydraulics: An integrated approach. Malden, MA: Wiley Blackwell.

  DOI: 10.1002/9781118526576

  This is the only major book that currently exists to span the entire breadth of ecohydraulics research. The book organized twenty-five distinct chapters by different authors into sets of methods, species-habitat interactions, and management applications. The quality of all of the articles is excellent. Individual chapters are not cited in this bibliography to save space for a diversity of authors, but all are recommended for reading as part of understanding ecohydraulics.

• Statzner, B., J. A. Gore, and V. H. Resh. 1988. Hydraulic stream ecology: Observed patterns and potential applications. Journal of the North American Benthological Society 7:307–360.

  DOI: 10.2307/1467296

  Visionary article presenting the essence of ecohydraulics. It draws on fourteen journal pages of literature references and discusses specific examples, primarily from studies of benthic macroinvertebrates. The article argues correctly that ecology must not settle for correlations between discharge and biota but look into the details of hydraulic and sediment transport mechanisms associated with biological processes that aggregate to ecological conditions. This insight is the guiding light of ecohydraulics.