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Utility of satellite-derived burn severity to study short- and long-term effects of wildfire on streamflow at the basin scale

Author(s): Hernan A. Moreno, Jonathan J. Gourley, Tri G. Pham, Daniela M. Spade
Year Published: 2020

We investigated the changes in hydrologic response in a forested catchment impacted by wildfire in Colorado U.S.A. from the storm event to the inter-annual scales. We also evaluated the utility of a remotely-sensed burn severity index to study post-fire shifts in streamflow. At the storm-scale, we evaluated hydrologic shifts through changes in the effective runoff (Q*/PTot), peak streamflow (Qpk) and response time (TR/TB) from multiple hydrographs, while at seasonal and inter-annual-scales we quantified hydrologic shifts through the runoff fraction (Q/PTot) and flow duration curves. Vegetation anomalies were monitored through comparisons of the Normalized Burn Ratio (NBR) between the burned and a hydrologically-similar, forested, neighboring, unburned catchment. We found short-term acute and long-term chronic transient streamflow shifts from the minute to the inter-annual scales. Flow duration curves indicate an order of magnitude increase in maximum flows. Event-average Q*/PTot increased by two orders of magnitude and Qpk increased by one order of magnitude relative to multiple representative pre-fire events of similar precipitation intensities. Decreases in TR/TB appear to be minimal. At the inter-annual scale, increases in the difference between simultaneous unburned and burned NBR are associated with increases in Q/PTot. A hydrologic recovery pathway is evident resembling a hysteresis effect driven by vegetation re-growth. Results illustrate the non-steady physical processes that increase flash-flooding risks post-fire in mountainous catchments and the utility of ΔNBR as a hydrologic predictor in ungauged watersheds.

Citation: Moreno, Hernan A.; Gourley, Jonathan J.; Pham, Tri G.; Spade, Daniela M. 2020. Utility of satellite-derived burn severity to study short- and long-term effects of wildfire on streamflow at the basin scale. Journal of Hydrology 580:124244. https://doi.org/10.1016/j.jhydrol.2019.124244
Topic(s): Fire Effects, Ecological - Second Order, Water
Ecosystem(s): None
Document Type: Book or Chapter or Journal Article
NRFSN number: 20717
FRAMES RCS number: 58956
Record updated: Feb 5, 2020