Case studies of instream flow modelling for fish habitat in canadian prairie rivers

Abstract

Fish habitats represent some of the most difficult ecological, biological, topographic and hydrodynamic phenomena to evaluate and simulate in detail. This reality has led to the development of diverse approaches and a variety of methodologies in an attempt to provide a scientific basis for river management decisions both for ice-free and ice-covered seasons. Hydrodynamic and computational advances, and particularly the introduction of 2-dimensional numerical models, have provided better tools and renewed impetus for tackling some of the complexities of habitat simulation and habitat changes with river discharge. The 2-dimensional, depth-averaged, finite element hydrodynamic model RIVER2D has been utilized for several study sites in Canada and the USA. The latest version of this model, with improved interface and documentation, as well as an ice-cover module is available at www.river2d.ca. The model was used for instream flow analyses at several sites on Canadian prairie rivers, including sections of the Kananaskis, the North and South Saskatchewan and the Assiniboine. The hydrodynamic results, coupled with biologically-significant suitability metrics, were used to develop relationships between weighted useable fish habitat areas and river discharge. As in most instream flow case studies, such analyses are supplemented by site-specific investigations and professional judgement, which can be guided by mimicking natural systems (physiomimesis). Preserving key components of natural hydrographs may have a higher chance of maintaining ecological function and is amenable to adaptive management frameworks. © 2003 Taylor & Francis Group, LLC.