STORMS, FLOODS AND FIRE: CHANGING DRYLAND LANDSCAPES DURING THE NORTH AMERICAN MONSOON

When coupled with detailed measurement of precipitation and hydrology, multi-temporal three-dimensional laser scanning, commonly referred to as terrestrial Light Detection and Ranging (LiDAR) by the geological community, is a powerful tool for understanding short-timescale geomorphic processes. At several geomorphically active field sites in desert and montane settings in the Southwest U.S., we have deployed rain gauges, streamflow sensors, and time-lapse cameras to measure the effects of monsoon rain events on erodible substrates. These sites include steep, low-order badland drainage basins, discontinuous ephemeral streams, and steep, severely burned montane hillslopes. Repeat terrestrial LiDAR scans before and after single and/or multiple significant precipitation events allow us to generate centimeter-level maps of landscape form and change. This allows quantification of both the spatial pattern and magnitude of erosion at a catchment scale, and relate landscape change explicitly to the magnitude of environmental forcing. The primary challenges we continue to address in this work are the development of appropriate vegetation removal protocols, and the development of proper methods to perform change detection with confidence in complex landscapes. By increasing confidence in our ability to link weather and hydrology to landscape change, we are poised to feed important field data to the landscape evolution modeling community, and perhaps make progress towards predicting the fate of dryland landscapes in the face of global climate change.