HR: 12:05h
AN: H52E-08    [Abstracts]
TI: High resolution, spatial distribution of unit stream power using ALSM-derived stream networks
AU: * Williams, K M
EM: karen.williams@myportal.montana.edu
AF: Montana State University, Department of Earth Sciences, Bozeman, MT 59718,
AU: Locke, W
EM: wlocke@montana.edu
AF: Montana State University, Department of Earth Sciences, Bozeman, MT 59718,
AB: Unit stream power is a measure of energy expenditure, as the channel does the work of transporting sediment and modifying channel morphology. The distribution of energy through the channel network creates a distribution of channel morphologic types by taking disorganized hillslope inputs of wood and sediment and creating channel structure, organization, and regularly spaced bedforms. Unit stream power has been used as a proxy for fluvial process, to establish causality between channel form and process. However, spatial distributions of unit stream power have been constrained by the coarseness of the available topographic data. ALSM data was used to create high resolution spatial distributions of unit stream power on a reach of headwater mountain stream. Spatial distribution of unit stream power at fine scales was used to detect spatial organization in a reach of Spring Park Creek, Tenderfoot Creek Experimental Forest, Montana. ALSM-derived digital elevation models of varying resolution were used to delineate stream networks. Channel slope derived from stream networks, discharge data from an in-situ gaging station, and field surveys of channel width were used to calculate unit stream power distributions at 0.5, 1.0, and 5.0 meter resolution. As a secondary method of calculating unit stream power, a HEC-RAS hydraulic model of the reach was created by cutting cross-sections through the ALSM-derived topography and inserting thalweg elevations to define channel inverts. This model was calibrated by stage- discharge data and field-derived roughness values. The HEC-RAS-calculated values of unit stream power were used to create spatial distributions of unit stream power. Spatial distributions of unit stream power derived by both methods were analyzed by spectral analysis for periodic behavior. The relative dominance of alluvial versus colluvial forcing constrains the degree of organization.
DE: 1824 Geomorphology: general (1625)
DE: 1825 Geomorphology: fluvial (1625)
DE: 1847 Modeling
DE: 1856 River channels (0483, 0744)
SC: Hydrology [H]
MN: 2007 Fall Meeting