Lithologic and Tectonic Controls on Bedrock Channel Form at the Northwest Himalayan Front

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Allen, George Henry
- Affiliation: College of Arts and Sciences, Department of Geological Sciences

Abstract

Recognition that channel form reflects a river's ability to erode rock has spawned stream-power models that estimate patterns of incision by approximating energy dissipation within a channel. Most commonly, these models assume channel width exponentially scales with drainage area, in part, because drainage area is easily extracted from digital elevation models (DEMs). However, this assumption is often confounded by local variations in rock strength and uplift rate that cause channel constriction downstream. Here we investigate the morphological response of 10 bedrock channels traversing the Mohand range at the northwest Himalayan front to spatial changes in rock strength and uplift rate. We present a new method to continuously measure and compare channel width, slope, and other hydraulic parameters using satellite image analysis and a DEM. Our results suggest that rock strength importantly influences channel form and that channel width should be explicitly measured when extracting tectonic signals from channel morphology.

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