Tectonic, climatic, and erosional process controls on topography, relief, denudation, and channel network structure

This research focuses on understanding the response of denudation and topography to changes in tectonic rock uplift rates and the distribution of geomorphic processes in space and time.  First, we have used high-resolution LiDAR Airborne Laser Swath Mapping data to measure the topography of a simple, soil-mantled landform along the San Andreas Fault in the Carrizo Plain, California, to understand how erosion and topography respond to changes in rock uplift rates (Hilley and Arrowsmith, 2008).  In this way, we used the ALSM data to directly image landscape changes that previously could only be inferred using numerical models.  These observations have been used in turn to test process-based models of landscape development (Hurst et al., 2013).  Secondly, we have been using a combination of high resolution topographic analysis, 10-Be denudation rate measurements, and numerical models to understand the dependence of landscape form and denudation on spatial and temporal changes in processes that erode and transport mass across Earth’s surface.  In particular, we have found from topographic analysis and 10Be-derived denudation rates measured within the Washington Cascades that postglacial denudation processes are especially sensitive to spatial variations in climate because of primarily the augmentation of mass failure in glacially oversteepened parts of this landscape, and secondarily variations in relief that record the imprint of climate-driven, asymmetric glacial extents within this range during the Last Glacial Maximum (Moon et al., 2011).  Finally, we have been using a suite of numerical models (Shelef and Hilley, 2013) to understand how the plan-view structure of channel networks may be related to erosional processes that form them (Shelef and Hilley, submitted).