Keywords

hydraulic modelling, aquatic habitat, wua, brown trout, stream morphology

Start Date

1-7-2006 12:00 AM

Description

A two-dimensional hydrodynamic model (River2D) was utilized to evaluate the relationship between geomorphic condition (as estimated using an existing rapid assessment protocol) and instream habitat quality in small Vermont streams. Six stream reaches ranging in geomorphic condition from good to poor according to the protocols were utilized for this study. We conducted detailed topographic surveys, quantified bed substrate, and measured velocity values during baseflow conditions. The reach models were calibrated with realistic roughness values based on field observations and pebble counts. After calibration, the flows were scaled up to median and bankfull flows for additional analysis. The weighted usable area (WUA) of habitat was calculated for each stream, at both median and bankfull flow, using the modeled parameters and habitat suitability curves for brown trout (Salmo trutta). Habitat for this fish was predicted using habitat parameters of velocity, depth, and channel substrate type suitabilities for adult, juvenile, and fry stages. The predictions of WUA, show a negative correlation to the stream geomorphic score, indicating that the often-used rapid protocols, do not directly relate to instream habitat conditions. Future research will include evaluating WUA at sub-reach scales, simulating additional flow conditions, expanding these WUA predictions to other species, computing additional habitat indices, and comparing modeled habitat parameters with actual biological data collected from these streams.

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Jul 1st, 12:00 AM

Two-Dimensional Hydraulic Modeling Approach to Linking Stream Morphology and Aquatic Habitat Quality

A two-dimensional hydrodynamic model (River2D) was utilized to evaluate the relationship between geomorphic condition (as estimated using an existing rapid assessment protocol) and instream habitat quality in small Vermont streams. Six stream reaches ranging in geomorphic condition from good to poor according to the protocols were utilized for this study. We conducted detailed topographic surveys, quantified bed substrate, and measured velocity values during baseflow conditions. The reach models were calibrated with realistic roughness values based on field observations and pebble counts. After calibration, the flows were scaled up to median and bankfull flows for additional analysis. The weighted usable area (WUA) of habitat was calculated for each stream, at both median and bankfull flow, using the modeled parameters and habitat suitability curves for brown trout (Salmo trutta). Habitat for this fish was predicted using habitat parameters of velocity, depth, and channel substrate type suitabilities for adult, juvenile, and fry stages. The predictions of WUA, show a negative correlation to the stream geomorphic score, indicating that the often-used rapid protocols, do not directly relate to instream habitat conditions. Future research will include evaluating WUA at sub-reach scales, simulating additional flow conditions, expanding these WUA predictions to other species, computing additional habitat indices, and comparing modeled habitat parameters with actual biological data collected from these streams.