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Control Erosion after a Wildfire

Control Erosion after a Wildfire

AUBURN, Ala.—Alabama is home to beautiful forests and hundreds of woodland creatures. The extreme drought settled into the south has wreaked havoc on the forest homes of woodland creatures. Wildfires have run rampant in the state with 1,721 fires burning more than 20,000 acres since the first of October.

Alabama’s Tennessee neighbors are currently fighting fires that have destroyed homes, businesses and tourist attractions. One of the biggest concerns following a wildfire is erosion control.

Post-fire erosion depends on many factors. Erosion hazard generally increases as slop increases and vegetative cover decreases. For safety purposes, assume all drainage in steep, hilly areas can carry debris flows after a wildfire.

Erosion

Amounts of erosion after a burn depends on storm events, burn severity, slope, soil-type and the condition of the post-fire watershed.

Erosion may be immediate, but can also continue throughout the span of several years as root systems of burnt vegetation decay.

Surface erosion is the movement of individual soil particles, usually by water flowing over expose soil. Debris flows and avalanches are dramatic forms of erosion. These events can deliver huge amounts of sediment and debris downslope.

For those who live on or near a slope, in a gully or ravine, or along a stream or river—be aware of the extent of wildfire damage upslope and upstream. When most or all of the vegetation has been burned off, the chance for erosion is significantly greater and can result in mass movements of soil and water downhill or downstream from damaged areas.

Control Methods

Erosion control is one of the most common rehabilitation activities after a burn. There are several common methods.

Mulch: Mulch covers the soil, reducing raindrop impact, overland flow, and soil particle movement. It also offsets the effects of water-repellent soils. Mulching is the only treatment that consistently and significantly reduces erosion rates by immediately increasing the percentage of good ground cover.

Mulch types include certified weed-free straw, slash and geotextile fabrics.

Barriers: Barriers are installed on hill slopes and in streams to slow water flow, increase infiltration and trap sediment. Types of barriers include log barriers, straw wattles, sandbags, silt fences and straw bale check dams.

Seedling and Revegetation: Grass seeding is the most common erosion control treatment following a burn. Grass is seeded to burned sites from the ground or by air to increase vegetative cover during the first few critical years after a fire.

Emergency Information

The Emergency Handbook brings together recommendations from national emergency response agencies and major universities into one easy-to-understand, interactive reference.  It addresses nearly 50 disaster preparation and recovery topics in four broad categories, including: People and Pets, Home and Business, Landscape and Garden, and Farms and Livestock.

For more information on emergency preparedness, visit www.aces.edu. The Emergency Handbook iBook is also available in pdf form and on iTunes. Contact your county Extension office for more information.

About Katie Nichols