MULTISCALE RIVER ENVIRONMENT CLASSIFICATION FOR WATER RESOURCES MANAGEMENT¹

Abstract

River Environment Classification (REC) is a new system for classifying river environments that is based on climate, topography, geology, and land cover factors that control spatial patterns in river ecosystems. REC builds on existing principles for environmental regionalization and introduces three specific additions to the “ecoregion” approach. First, the REC assumes that ecological patterns are dependent on a range of factors and associated landscape scale processes, some of which may show significant variation within an ecoregion. REC arranges the controlling factors in a hierarchy with each level defining the cause of ecological variation at a given characteristic scale. Second, REC assumes that ecological characteristics of rivers are responses to fluvial (i.e., hydrological and hydraulic) processes. Thus, REC uses a network of channels and associated watersheds to classify specific sections of river. When mapped, REC has the form of a linear mosaic in which classes change in the downstream direction as the integrated characteristics of the watershed change, producing longitudinal spatial patterns that are typical of river ecosystems. Third, REC assigns individual river sections to a class independently and objectively according to criteria that result in a geographically independent framework in which classes may show wide geographic dispersion rather than the geographically dependent schemes that result from the ecoregion approach. REC has been developed to provide a multiscale spatial framework for river management and has been used to map the rivers of New Zealand at a 1:50,000 mapping scale.

Flow variability and macroinvertebrate community response within riverine systems

“…Hydrological classification is now widespread (Hannah, et al, 2000;Snelder and Biggs, 2002) although the integration with ecological data is rare but an essential process for true hydroecological investigations (Hannah, et al, 2004). The results of this research demonstrate the importance of recognising rivers with different hydrological regimes and the dominance of flow magnitude (monthly and annual extremes) in shaping instream communities in England and Wales.…”

Implementation of an eco-hydrological classification in Chilean rivers

“…The controlling factors selected for the implementation of REC-Chile are based on those used in the REC developed by Snelder and Biggs (2002) for New Zealand, adapted to the climatic and environmental conditions of Chile. The controlling factors selected were: Climate, Source of Flow, Geology, Catchment Relative Position, Land Use and Reach Slope.…”

“…The ecoregions are homogeneous zones with regard to certain characteristics or parameters on a determined spatial scale (Snelder et al 2005;Omernik & Bailey 1997;Bailey et al 1978). Snelder and Biggs (2002) pointed out that these ecoregions are unable to represent the longitudinal gradients in a river ecosystem, which were synthesized in the River Continuum Concept (Vannote et al 1980); therefore the use of such ecoregions for river classifi cation are limited.…”

“…Therefore, it is expected that the rivers are being infl uenced by the watershed characteristics, accepting that ecological processes in a river depend on physical factors which occur at several scales (González del Tánago & García de Jalón 2006, Snelder & Biggs 2002, Montgomery & Buffi ngton 1997, Omernik & Bailey 1997, Frissell et al 1986). Snelder and Biggs (2002) developed the River Environmental Classifi cation (REC) to classify the rivers of New Zealand based on the following premises: a) Ecological patterns are dependent on a number of factors associated with the regional scale of the various physical processes; b) The ecological characteristics of rivers respond to fl uvial processes; and c) Classes are assigned to each segment of river geographically independent. In the REC, the typology of each river segment is determined by the hierarchical superposition of controlling factors, which are the principal causes of the spatial variation of the hydrological pattern at a determined scale (Snelder et al 2005, Snelder & Biggs 2002.…”

“…Snelder and Biggs (2002) developed the River Environmental Classifi cation (REC) to classify the rivers of New Zealand based on the following premises: a) Ecological patterns are dependent on a number of factors associated with the regional scale of the various physical processes; b) The ecological characteristics of rivers respond to fl uvial processes; and c) Classes are assigned to each segment of river geographically independent. In the REC, the typology of each river segment is determined by the hierarchical superposition of controlling factors, which are the principal causes of the spatial variation of the hydrological pattern at a determined scale (Snelder et al 2005, Snelder & Biggs 2002.…”