An observational framework for quantifying post-fire runoff and sediment response
Abstract
Wildfires are a complex and universal problem across the western U.S, dramatically increasing watershed sedimentation rates and concentrations of dissolved organic matter (DOM), representing a major challenge for water treatment. To address this problem, we developed laboratory-scale rainfall and wildfire simulators to measure the sediment and runoff responses from soils subjected to a range of burn severities, rainfall intensities, and terrain slopes. Best practices for capturing burn, rainfall, and terrain-related processes in the laboratory are discussed, including the key experimental settings that represent conditions typical of fires in northern Colorado. Results from burn temperatures between moderate and severe (150 to 550°C), and rainfall intensities between 20-yr and 100-yr storms (0.76 to 2.5 in/hr), are presented. We set the stage by first presenting model-generated synthetic results of sedimentation response, as well as infiltration and runoff amounts, to anticipate dominant factors and processes. Next, we present laboratory results from samples collected from a steep mountain catchment with a record of wildfires as recent as 2012: the Cache la Poudre (CLP) Basin near Fort Collins, CO. Samples were exposed to different combinations of burn severities, rainfall intensities, and representative terrain slopes, with differences in runoff, sedimentation, and DOM exports analyzed across these dimensions. Preliminary laboratory results are evaluated against model-simulated synthetic results, with implications for post-fire response, including issues related to model transferability, and the longer-term goal of up-scaling these results to the catchment scale.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.H23S2179B
- Keywords:
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- 1813 Eco-hydrology;
- HYDROLOGY;
- 1824 Geomorphology: general;
- HYDROLOGY;
- 1860 Streamflow;
- HYDROLOGY;
- 1871 Surface water quality;
- HYDROLOGY