Abstract
Wildfires can dramatically increase erosion rates over time scales on the order of several years, yet few data firmly constrain the relative importance of post-wildfire erosion in the long-term denudation of landscapes. We tested the hypothesis that wildfire-affected erosion is responsible for a large majority of long-term denudation in the uplands of the Valles Caldera, New Mexico, by quantifying erosion rates in wildfire-affected and non-wildfire-affected watersheds over short (~100–101 years) time scales using suspended sediment loads, multitemporal terrestrial laser scanning, and airborne laser scanning and over long (~103–106 years) time scales using 10Be inventories and incision into a dated paleosurface. We found that following the Las Conchas fire in 2011, mean watershed-averaged erosion rates were more than 1000 µm yr−1, i.e., ~103–105 times higher than nearby unburned watersheds of similar area, relief, and lithology. Long-term denudation rates are on the order of 10–100 µm yr−1. Combining data for wildfire-affected and non-wildfire-affected erosion rates into a long-term denudation rate budget, we found that wildfire-affected erosion is responsible for at least 90% of denudation over geologic time scales in our study area despite the fact that such conditions occur only at a small fraction of the time. Monte Carlo analyses demonstrate that this conclusion is robust with respect to uncertainties in the rates and time scales used in the calculations.
Original language | English (US) |
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Pages (from-to) | 843-864 |
Number of pages | 22 |
Journal | Journal of Geophysical Research: Earth Surface |
Volume | 121 |
Issue number | 5 |
DOIs | |
State | Published - May 1 2016 |
Keywords
- Valles Caldera
- cosmogenic isotopes
- erosion
- lidar
- post-wildfire
ASJC Scopus subject areas
- Geophysics
- Earth-Surface Processes