Publisher's Synopsis
This report is a synthesis of post-fire emergency hillslope stabilization treatment effectiveness information that was written to provide guidance for future post-fire treatment selection and use. It builds on an earlier synthesis, Evaluating the Effectiveness of Postfire Rehabilitation Treatments (Robichaud and others 2000). Since that publication, the effectiveness of emergency post fire hillslope treatments have been evaluated in several scientific studies and treatment monitoring reports prepared by Burned Area Emergency Response (BAER) and Emergency Stabilization and Rehabilitation (ESR) teams. In addition, our knowledge of how environmental factors impact treatment effectiveness and the development of new post-fire hillslope treatment products and application techniques has grown. The objective of this document is to synthesize that new information in a format that is easily accessible by post-fire assessment teams and land managers. This synthesis focuses on post-fire hillslope emergency stabilization treatments, including erosion barriers, mulching, chemical soil treatments, and combinations of these treatments. This is a narrow focus given the range of post fire emergency responses typically implemented by BAER teams (see Napper 2006 for a comprehensive review of post-fire treatments). However, these hillslope treatments are usually the most expensive post-fire treatments used, which makes cost effectiveness an important factor in their selection. Post-fire stabilization treatments for roads are frequently implemented to facilitate the passage of potentially larger post-fire water flows that may damage roadways, culverts, bridges, etc. These treatments and their known effectiveness have been addressed in A Synthesis of Post-Fire Road Treatments for BAER Teams (Foltz and others 2009) and are not included in this synthesis. Post-fire treatments to stabilize channels or deflect large channel flows are occasionally recommended after wildfires, but there are few quantified data on treatment performance, and those treatments are not discussed in this document. However, some hillslope treatment effectiveness studies have been done on swales, hillslope plots that contain two convergent hillslopes that form a zeroorder channel, and small catchments that contain one or more low-order channels with a clearly defined outlet. In these studies, the measured eroded sediment is trapped at the base of the hillslope swale or at the outlet of the low-order catchment channel system and includes the eroded sediment from the hillslopes and channels within the contributing area. Those studies are included in this synthesis because hillslope stabilization treatments (as opposed to channel treatments) were evaluated. We have synthesized the available post-fire hillslope treatment effectiveness research and monitoring data that apply to the United States. However, with few exceptions, the data are from studies done in the western United States. There are some post-fire hillslope treatment studies from Europe, particularly Spain and Portugal, but the majority of the relevant research is from the western United States where hillslope treatments have been implemented after large wildfires. Wildfires do occur in the central and eastern United States, but post-fire hillslope stabilization treatments are rarely implemented, and there are few or no available data on treatment effectiveness. Generally, post-fire recovery occurs more rapidly in these wetter climates than in the drier western forest. However, with climate change, the risk of larger and more severe wildfires is becoming increasingly important in areas like the southeastern piedmont. The treatment effectiveness information that has been generated in the western United States will likely apply to other areas if post-fire treatments are warranted.
