A technique using multiple images from a single year to find surface roughness-based differences in directional radiance across sparsely-vegetated surfaces has been developed to help efficiently map and understand depositional processes on active, alluvial fan surfaces in Death Valley, CA. Surface roughness on the scales of grain size and topography on alluvial fan surfaces is expected to vary with depositional processes, including fluvial and mass movement events, as well as surface runoff and eolian processes. The Bidirectional Reflectance Distribution Function (BRDF) describes changes in reflectance based on changes in the angle of irradiance and radiation-scattering effects of a surface. Using Landsat 7 satellite imagery, the changes in observed surface reflectance, resulting from seasonal changes in the angle of incoming, solar radiation, can be classified and interpreted to show differences in surface roughness. Observations of grain size and topography, and other variables that affect reflectance (e.g. vegetation, composition) from field sites on eastern, alluvial fan surfaces in Death Valley show that seasonal changes in surface radiation are related to surface shadowing that result from grain size primarily, but also topography. Statistical tests show that the total amount of sand found on the land surface is the most correlated variable with the remote sensing method. Spatial relationships of surface features provide further interpretation of depositional process in addition to surface roughness. Airborne Laser Swath Mapping (ALSM) data was also used to map surface roughness, and shows positive trends with the Landsat imagery analyses. Mapping surface roughness over large areas and in remote settings using multi-spectral, satellite imagery has the potential to be a powerful tool for studying the geomorphology of both Earth and Mars.
Earth and Planetary Sciences
Level of Degree
Department of Earth and Planetary Sciences
First Committee Member (Chair)
Second Committee Member
Doyle, Sarah. "REMOTELY MAPPING SURFACE ROUGHNESS ON ALLUVIAL FANS: AN APPROACH FOR UNDERSTANDING DEPOSITIONAL PROCESSES." (2013). https://digitalrepository.unm.edu/eps_etds/20