Author(s): Thomas Hardy; Damon H. Goodman; Russell W. Perry; Nicholas A. Som
Linked Author(s): Thomas Hardy
Keywords: No Keywords
Abstract: A novel approach to the delineation of Hydraulic Habitat Units (HHUs) is presented using the classification of at-a-station Hydraulic Geometries (AHG) based continuity equation exponents. HHU delineations were similar to ground based mesohabitat (MHT) mapping results collected at mean baseflow discharge but have the advantage of integrating hydraulic and channel characteristics over a range of flows and are therefore insensitive to the flow rate dependent results of ground based MHT mapping methodologies. Application of the approach can be accomplished using three-dimensional channel topographies derived from LiDAR and/or hydroacoustic mapping overlaid with cross sections generated for river specific target longitudinal spacing. The extracted channel geometries at each cross section can then be used to estimate the wetted width at three or more flows derived from available aerial or satellite photography using existing GIS tools. These values provide the cross section specific estimate of the AHG width exponent. The corresponding channel geometries then allow estimated mean channel depths at the three discharges which provides the cross section specific estimates of the AHG depth exponents. The continuity equations for mass balance provides the cross section specific estimates of the corresponding AHG exponent for velocity. The b-f-m ternary classification of Rhodes (1977) is then utilized with a classification algorithm to define HHU boundaries. Established 1-dimensional hydraulic simulation techniques can subsequently be used to estimate the cross section specific variations in depth and velocity for use in physical habitat modeling suitable for supporting full life cycle models. This approach inherently estimates the expected variability in the hydraulic properties due to the explicit representation of the variability in the channel cross section properties within each HHU.
Year: 2018