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Empirical in-stream flow assessment tools for British Columbian channels

University of British Columbia

Empirical hydraulic distribution equations have been proposed as simple and inexpensive alternatives to traditional data-intensive flow assessment methodologies. Two proposed depth and three proposed velocity empirical equations were compared to measured hdraulic distributions for two channels in the Interior Region of British Columbia. Empirical velocity distributions adequately reproduced the measured velocity distribution for both channels. An empirical depth distribution was able to replicate measured depth distributions at a relatively undisturbed channel (Harris Creek) but were unable to predict the measured depth distribution following morphological change at a channel recently disturbed by forest fire (Fishtrap Creek). Furthermore, the empirical distributions were compared to modelled depth and velocity distributions produced by a 2-dimensional hydrodynamic model (River2D). The empirical distributions provided reasonable representation of the hydraulic distributions for flows < 3 m³ s-¹. At flows approaching bankfull the empirical methods, in particular the velocity equations, were unable to adequately reproduce the distributions produced in River2D. Additionally, a joint frequency depth-velocity distribution was paired with habitat suitability indices to quantify available habitat across a range of flows at Harris Creek using reach average hydraulic conditions generated by River2D. The statistical habitat model produced similar habitat values to River2D at low flows and was able to recreate the general shape and trends of the habitat indices. As well, a proposed at-a-station hydraulic geometry simulator was used alongside a channel regime model to approximate reach average channel conditions at Harris Creek. The proposed hydraulic simulator was able to accurately predict reach average depth (mean error of 1.06 %) and velocity (4.47 %) for discharges ranging from daily low flow to bankfull flow. The hydraulic simulator was coupled with the statistical habitat model to generate hydraulic distributions and subsequently habitat indices for the modelled discharges. The incorporation of the regime models allows users to examine the influence of variable flow regimes and riparian vegetation (inherent of a changing climate) on available aquatic habitat. The proposed aquatic habitat model provides practitioners with a low-input, user-friendly flow assessment tool that can be used for preliminary habitat assessments and basin-wide habitat studies in British Columbia.

Text

2013-09-09

CC0 1.0 Universal

http://hdl.handle.net/2429/45054

Geography

University of British Columbia

UBCV

http://creativecommons.org/publicdomain/zero/1.0/