Title

Rapid response tools and datasets for post-fire erosion modeling: An online database to support post-fire erosion modeling

Document Type

Conference Paper/Presentation

Publication Date

12-2013

Abstract

Once the danger posed by an active wildfire has passed, land managers must rapidly assess risks posed by post-fire runoff and erosion due to fire-induced changes in soil properties and the loss of surface cover. Post-fire assessments and proposals to mitigate risks to downstream areas due to flooding, erosion, and sedimentation are typically undertaken by interdisciplinary Burned Area Emergency Response (BAER) teams. One of the first and most important priorities of a BAER team is the development of a burn severity map that reflects the fire-induced changes in both vegetative cover and soils. Currently these maps are known as BARC (Burned Area Reflectance Classification) maps and they are generated from multi-spectral remote sensing data. BAER teams also have access to many erosion modeling tools and datasets, but process-based, spatially explicit models are currently under-utilized relative to simpler, lumped models because they are more difficult to set up and they require the preparation of spatially-explicit data layers such as digital elevation models (DEM), soils, and land cover. We are working to make spatially-explicit modeling easier by preparing large-scale spatial data sets that can be rapidly combined with burn severity maps and then used to quickly run more accurate, process-based models for spatially explicit predictions of post-fire erosion and runoff. A prototype database consisting of 30-m DEM, soil, land cover, and Monitoring Trends in Burn Severity (MTBS) maps for Colorado has been created for use in GeoWEPP (Geo-spatial interface for the Water Erosion Prediction Project) with Disturbed WEPP parameters developed for post-fire conditions. Additional soil data layers have been gathered to support a spatial empirical debris flow model that also utilizes BARC maps. Future plans include developing the dataset to support other models commonly used by BAER teams. The importance of preparing spatial data ahead of time can be illustrated with two contrasting modeling exercises from recent fires. The 2012 High Park Fire that burned near Fort Collins, Colorado and a small portion of the 2011 Rock House Fire (Hospital Canyon) that burned in western Texas. A lack of preparatory work meant useful products could not be produced in a timely manner for the Rock House Fire. In contrast, an earlier project meant that baseline soil and land cover data were readily available for the 2012 High Park Fire, which burned 330 km2 and threatened the drinking water for Fort Collins, Greeley, and other downstream communities. These datasets were combined with the burn severity map and used to model post-fire erosion and run-off in GeoWEPP using a two hour storm event with a total rainfall of 2.2 inches. Predictions of post-fire erosion rates ranged from 0 to 10.4 Mg/ha and the maps were used by the BAER team to assess relative erosion risks, and develop the associated proposals for post-fire mitigation efforts.

Publisher's Statement

© 2013 American Geophysical Union.

Publication Title

AGU Fall Meeting 2013