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Wildfire Planning (post)

Provide Key Information in a Post Wildfire Environment (BAER)

Post-wildfire management is concerned with the aftermath of fire including increased runoff leading to intense flooding, accelerated erosion in the form of surface erosion, landsliding, gullying, and debris flows. Existing gravel and native surface roads may also become area of accelerated erosion, including road surface erosion and gullying. On the federal agency side, the immediate post-fire response planning is referred to as “Burned Area Emergency Response” or BAER.

Increased erosion and flooding can impact channels, homes, ighways, and aquatic habitats with their associated threatened and endangered species. The sequence of events following a fire is referred to as a “wildfire cascade.”

See Post-Fire results in the Malheur National Forest: PPT-PDF

 

 

 

 

TerrainWorks (NetMap) tools are used to identify areas within watersheds where the highest fire intensity (based on Burned Area Reflectance Classification or BARC maps) overlaps the highest post-fire erosion potential (surface erosion, gullying, mass wasting) and where they intersect areas of the highest habitat sensitivity.

 
 
 
 
 

Inform Restoration Planning

Post-wildfire planning may include strategic placement of erosion control activities including:

(1) grass seeding, 
(2) hay bales,
(3) in-channel structures (in stream restoration), 
(4) realignment of roads on valley floors or on floodplains, and
(5) road maintenance and abandonment, including replacing stream crossing structures to enable increased fish passage and the transport of additional sediment and debris.
In TerrainWorks, post-fire planning can be supported with a series of 80 tools within the Digital Landscapes.
 

First, burn intensity data such as a Burned Area Reflectance Classification (BARC) map are typically in the form of a grid or raster. These data indicate which areas burned the hottest and thus which areas (including stream channels) have the highest potential for extreme erosion, sedimentation, and flooding. 
 
In TerrainWorks, burn severity information is transferred from the terrestrial landscape to stream channels, yielding a “fish-eye” or in-channel view of burn severity. 
 
Second, predicted erosion response to burn severity is mapped onto hillsides and reported to stream channels. Erosion responses include surface erosion, gullying, and landslides.
 

Relevant erosion models in TerrainWorks include:

  • Surface erosion (WEPP-Disturbed)
  • Shallow landslide
  • Gullying
  • Debris flow
  • Road drainage diversion and road surface erosion

Third, tools in TerrainWorks are used to identify the risk from landslides, gullies, and debris flows.

Fourth, TerrainWorks is used to map valuable and sensitive aquatic habitats, inclusive of threatened and endangered fish species. Users can create maps with existing published models or by using their own models using a host of TerrainWorks (NetMap) parameters.

 

 

 

Fifth, Connect the Dots: Burn Severity – Erosion Risk – Habitat Quality or Sensitivity.

For example, using the TerrainWorks  Risk Assessment Overlap Tool, a user can quickly search for the locations where the top 5% of burn severity overlaps with the top 5% of erosion potential and where that pair overlaps the top 1% of fish habitat quality.

Sixth, include road-related impacts. See Road Tools.

In a post-fire environment, roads can be a major source of impacts. In the intense surface erosion and raveling environment, culverts and secondary drainage structures can become plugged. This will lead to increased drainage diversions and potentially to accelerated erosion in the form of road surface erosion, gullying, shallow landsliding, and debris flows. In addition, debris backed up behind culverts and other drainage structures can create fish migration barriers.

 

TerrainWorks (NetMap) contains a suite of road tools that can support a rapid analysis of potential road related impacts including:

  • Importing your own road layer (or use the one provided in the Digital Hydroscape datasets)
  • Predicting road drainage diversion potential (either worse case scenarios following fires or based on knowledge of drainage spacing or provide your own drainage [culvert] points in a shapefile)
  • Predicting road surface erosion potential using one of three methods
  • Predicting the potential for road related shallow landsliding and debris flows
  • Calculating the cumulative length (and quality) of fish habitat upstream of every road crossings
  • Classifying all road-stream crossings by habitat quality, sensitivity, and channel type
  • Mapping road intersections with floodplains

See NetMap's Wildfire Cascade Tool.

See NetMap's Fire-Erosion-Habitat Tool for use in BAER.

See the Online Viewer  for post fire data distribution.