State-of-the-art and perspectives of habitat modelling for determining conservation flows

Abstract

The objective of this paper is to review current knowledge and techniques presently being used and developed to estimate or simulate aquatic habitat availability and quality, in order to determine the most appropriate flow regime. These methods were reviewed at a recent workshop held in Québec City on March 4 and 5, 2003. Papers in this special issue of the Journal were written by the keynote speakers invited to the workshop. Our paper provides a broad overview of their findings, as well as a survey of the state-of-the-art.Existing instream flow estimation methods include hydrologic, hydraulic and habitat model approaches. These methods present a gradient of complexity and thus an increasing number of variables are included to account for the heterogeneity of aquatic habitat. The third category, habitat modelling, is the most elaborate of the three and will be the main focus of this paper.The main modelling issues and concerns raised at the workshop can be categorized into the following main themes: the available modelling strategies, the parameterization of habitat preferences of the target species during their life cycles, the behavioural modelling of intra- and interspecific relationships within ecosystems, the selection of proper spatial and temporal scales to represent the habitat, the validation strategies, and the choice of minimum levels of river discharge based on modelling results. The workshop also considered complementary concerns such as the related characterization schemes and digital terrain modelling required for habitat modelling, the use of compensatory works to optimize the benefits of minimum flow regimes and finally, the use of Multimetric Biotic Integrity Indices for following-up hydraulic projects and the impacted ecosystems after the implementation of water works or management schemes which disturb the natural hydrological regime. © 2003 Taylor & Francis Group, LLC.