|Shields Jr, Fletcher
|RIGBY, J.R. - UNIV. LONDON
Submitted to: Environmental Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/11/2005
Publication Date: 10/1/2005
Citation: Shields Jr, F.D., Rigby, J. 2005. River habitat quality from river velocities measured using acoustic doppler current profiler. Environmental Management. 36(4): 565-575.
Interpretive Summary: Rivers are valuable aquatic habitats, but measurement of habitat quality is difficult because water depth and velocity are always varying in time and space. A recently-developed technology, the acoustic Doppler current profiler was adapted for rapidly measuring water depth and velocity at many points within a river, and software was prepared to organize the data and compute indices of habitat quality. Indices were generally higher in reaches with complex velocity patterns, and thus higher quality aquatic habitat. With refinement, this approach may be used to efficiently measure the effects of channel erosion, channel modification, or changes in streamflow on river habitats.
Technical Abstract: Prior research has demonstrated the utility of metrics based on spatial velocity gradients to characterize and describe stream habitat, with higher gradients generally indicative of higher levels of physical heterogeneity and thus habitat quality. However, detailed description of the velocity field needed to compute these metrics is difficult to obtain. Acoustic Doppler current profilers (ADCP) may be used to rapidly collect detailed representations of river velocity fields. Such data were collected from four reaches of the Little Tallahatchie River in northern Mississippi. Sampled reaches were selected in order to observe velocity regimes associated with three distinctly different conditions: downstream from a major flow obstruction (a low weir), downstream from the apices of each of two sharp bends, and within an extremely long, straight reach created by channelization. Three-dimensional velocity data sets from each site were used to compute metrics of habitat quality proposed by others. A habitat metric based on the spatial gradient of kinetic energy proved to be the best discriminator among conditions within the sampled reaches. Two of four habitat quality metrics computed from these measured velocities were greatest for the sharpest meander bend. ADCP hold great potential for study of riverine physical aquatic habitats, particularly at the reach scale. Additional work is needed to develop generally applicable field protocols and data reduction tools. Specifically, guidelines for ADCP settings and configuration appropriate for a range of riverine site conditions must be developed. Advances in instrumentation are needed to allow collection of information in closer proximity to the free surface and solid boundaries.