Cataloging Information
Ecological - Second Order
Water
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
Access this Document
Treesearch
publication access with no paywall
Check to see if this document is available for free in the USDA Forest Service Treesearch collection of publications. The collection includes peer reviewed publications in scientific journals, books, conference proceedings, and reports produced by Forest Service employees, as well as science synthesis publications and other products from Forest Service Research Stations.