Current Research Interests
How does sediment move after a wildfire?
Wildfires enhance sediment transport, especially on steep (slopes > 30 degrees) mountainous terrain. We look at the mountains in Southern California because they are on fire very often and because we have a lot of data there. A lot of sediment moves from the hillslopes to the channels as dry ravel - a process where sediment rolls, bounces, or slides down hill and this happens during and immediately after the fire. We find that a lot more dry ravel occurs on steep slopes, where there is more shrubs that burned, and on specific rock types.
Collaborators: Dr. Roman A. DiBiase *amazing advisor!
Figure Credit: BTF
What happens to "burned" sediment after it rains?
Wildfires leave the ground scorched and devoid of vegetation, which reduces the ability of soil to absorb water. When it rains alot this can increase the risk of flash flooding and post fire debris flows (top figure). Post fire debris flows are slurries of sediment and water that are move fast (>20 mph), cause millions in damages to infrastructure, and threaten human lives. In Southern California, we look at how sediment stored in the channels as dry ravel (bottom left) relates to how debris flows (bottom right) occur. We find that in the San Gabriel Mountains, areas with a lot of dry ravel also had debris flows that occurred. But in the San Bernardino Mountains, we find that debris flows only happen in areas that had a lot of rain and amount of dry ravel was not as important.
Collaborators: Dr. Roman A. DiBiase
Figure (top) Credit: NWS, Figure (bottom left) Credit: RAD , Video (bottom right) Credit: San Bernardino County Public Works
How do slot canyons form? Why are they deep and not wide like "normal" rivers?
Slot canyons, bedrock rivers that are deeper than they are wide, are often found on massive sandstones in arid climates with highly variable precipitation. However, in the same slot canyon, there are differences in how wide the channels are and differences in channel side walls (notice the undulations, the concavities on the side walls). We use field observations and modelling to explain how slot canyons form and they differ over time.
Collaborators: Michael J. Robinson, Maryn A. Sanders (these folks are amazing! check our their awesome research!!!)
With Advising and Input from: Dr. Joel S. Scheingross, Dr. Roman A. DiBiase
Previous Research Interests
How does sediment move out of a burned mountain?
Wildfires adversely affect the landscape especially in semi-arid, steep mountainous terrain, leading to landslides and debris flows. We have studied the hydrological and sedimentological response of a small watershed after the 2018 Holy Fire in the Santa Ana Mountains, California and determined how the amount of sediment changes over time. Check out the article below!
Collaborators: Dr. James J. Guilinger, Dr. Andrew B. Gray, & Dr. Nicolas C. Barth.
Figure Credit: JJG
How do microplastics float or sink in streams and rivers?
The current approach to assessing and modeling the fluvial transport of microplastics in riverine systems is limited to surface sampling. This approach does not account for all microplastics, some of which are neutral or negatively buoyant. Here, we modified the Rouse profile to account for all microplastics and use this adaptation to estimate the bias and uncertainty from from the use of surface samples compared to depth stratified sampling in estimating depth-averaged concentrations. Check out the article below!
Collaborators: Win C. Cowger, Dr. Andrew B. Gray, James J. Guilinger, & Dr. Kryss Waldschläger.
Figure Credit: WCC
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When it rains enough to trigger landslides how do boulders move?
In December 2010, a big rainstorm produced multiple storms that saturated the Box Springs and Blue Mountains, California, leading to soil slips and the transport of boulders along the hillslope and channels. The main objective of this project was to track boulders displaced from landslides from source to sink and quantify boulder movement. Further analyses were done to understand the process of landform remodeling and determine the topographic controls on total boulder runout distance.
Collaborators: James J. Guilinger, Dr. Andrew B. Gray, & Dr. Nicolas C. Barth
Figure Credit: BTF (mapping), Landsat Imagery 2009/2011 (aerial imagery)