HR: 1340h
AN: H53D-0492    [Abstracts]
TI: Using HEC-RAS to Enhance Interpretive Capabilities of Geomorphic Assessments
AU: * Keefer, L L
EM: lkeefer@uiuc.edu
AF: Illinois State Water Survey, 2204 Griffith Drive, Champaign, IL 61820 United States
AB: The purpose of a geomorphic assessment is to characterize and evaluate a fluvial system for determining the past watershed and channel conditions, current geomorphic character and potential future channel adjustments. The geomorphic assessment approach utilized by the Illinois State Water Survey assesses channel response to disturbance at multiple temporal and spatial scales to help identify the underlying factors and events which led to the existing channel morphology. This is accomplished through two phases of investigation that involve a historical and physical analysis of the watershed, disturbance history, and field work at increasing levels of detail. To infer future channel adjustments, the geomorphic assessment protocol combines two methods of analyses that are dependent on the quantity and detail of the available data. The first method is the compilation of multiple lines of evidence using qualitative information related to the dominant fluvial environment, channel gradient, stream power thresholds, and channel evolution models. The second method is the use of hydraulic models which provide additional interpretative skills to evaluate potential channel adjustments. The structured data collection framework of the geomorphic assessment approach is used for the development of a HEC-RAS model. The model results are then used as another tool to determine the influence of bridges and control structures on channel stability, stream power profiles to identify potential channel bed degradation zones, and provide data for physically-based bank stability models. This poster will demonstrate the advantages of using a hydraulic model, such as HEC-RAS, to expand the interpretive capabilities of geomorphic assessments. The results from applying this approach will be demonstrated for the Big Creek watershed of the Cache River Basin in southern Illinois.
DE: 1815 Erosion
DE: 1825 Geomorphology: fluvial (1625)
DE: 1847 Modeling
DE: 1856 River channels (0483, 0744)
DE: 1860 Streamflow
SC: Hydrology [H]
MN: Fall Meeting 2005