HR: 1340h
AN: H43E-1674    [Abstracts]
TI: Creating and coupling a high-resolution DEM with a 1-D hydraulic model in a GIS for scenario-based assessment of avulsion hazard in a gravel bed river
AU: * Aggett, G R
EM: gra@riverside.com
AF: Riverside Technology inc, 2290 E Prospect road, Fort Collins, CO 80525, United States
AB: This paper explores the development and assimilation of a high resolution topographic surface with a one- dimensional hydraulic model for investigation of avulsion hazard potential on a gravel bed river. A detailed LiDAR- based channel and floodplain surface model is created to define the geometry parameter required by the 1D hydraulic model HEC-RAS. The ability to extract dense and optimally located cross-sections is presented as a means to optimize HEC-RAS performance. A number of flood scenarios are then run in HEC-RAS to determine the inundation potential of modeled events, the post-processed output of which facilitates calculation of spatially explicit shear stress and level of geomorphic work (specific stream power per unit bed area) for each of these. Further enhancing this scenario-based approach, the DEM is modified to simulate a LWD jam and active-channel sediment aggradation to assess impact on innundation, shear stress and stream power under previously modeled flow conditions. The high resolution DEM facilitates overlay and evaluation of modeled scenario results in a spatially explicit context containing considerable detail of hydrogeomorphic and other features influencing hydraulics (bars, secondary and scour channels, levees). This offers advantages for: (i) assessing the avulsion hazard potential and spatial distribution of other hydrologic and fluvial geomorphic processes; and (ii) exploration of the potential impacts of specific management strategies on the channel.
DE: 1640 Remote sensing (1855)
DE: 1819 Geographic Information Systems (GIS)
DE: 1855 Remote sensing (1640)
DE: 1894 Instruments and techniques: modeling
SC: Hydrology [H]
MN: 2007 Fall Meeting