Evaluating the effectiveness of contour-felled log erosion barriers as a post-fire runoff and erosion mitigation treatment in the western United States

Abstract

Between 1998 and 2002, six sites were established immediately after large wildfires in the western United States to determine the effectiveness of contour-felled log erosion barriers in mitigating post-wildfire runoff and erosion. In each pair of matched, burned, and small watersheds (1–13 ha), one was treated with contour-felled log erosion barriers and one was left untreated as a control. For 4 to 6 post-fire years, runoff and sediment yields were measured and correlated with rain properties. High-intensity rainfall produced most of the measured runoff and sediment yields except in the southern California site, where long-duration rain events produced most of the runoff and erosion. For small rain events (less than the 2-year return period for the 10-min duration), the runoff, peak flows, and sediment yields were lower in the treated watersheds than in the control watersheds, but there was no treatment effect for rain events with larger return periods. Improper installation and degradation over time reduced the effectiveness of contour-felled log erosion barriers. Rainfall characteristics and installation procedures should be carefully considered before choosing contour-felled log erosion barriers for post-fire hillslope stabilisation.

Control del arrastre de sedimentos post-incendio: efectividad de fajinas en un bosque seco montañoso (Salta, Argentina)

“…La acumulación de sedimentos lograda con estructuras que disminuyen o frenan la velocidad del agua de lluvia y, por lo tanto, del arrastre de sedimentos, fue documentado en varios ecosistemas mediterráneos (Wagenbrenner et al 2006;Robichaud et al 2008;Vásquez and Tapia 2011;Díaz-Raviña et al 2012;Prats et al 2012;Robichaud et al 2013;Gómez-Rey et al 2014;Prats et al 2014). Sin embargo, en dichos estudios se comprobó la efectividad de técnicas diferentes a las fajinas (zanjas de infiltración, "hidromulching", "mulching" y siembra de vegetales, entre otros), y son pocos los estudios que usan estructuras similares.…”

“…Una técnica similar a las fajinas consiste en la utilización de troncos o ramas gruesas de árboles muertos por el incendio, colocados en el sentido de las curvas de nivel. Esta técnica resultó efectiva en bosques incendiados de Estados Unidos, que contenían entre 7 y 32 m 3 /ha de sedimentos (Wagenbrenner et al 2006), especialmente en eventos breves de lluvia, pero no así con lluvias más frecuentes e intensas (Robichaud et al 2008). Sin embargo, no conocemos estudios que hayan comparado la efectividad de trabajar con diferente densidad de estructuras que controlen el arrastre de sedimentos.…”

Post-Wildland Fire Desertification: Can Rehabilitation Treatments Make a Difference?

“…Burned Area Emergency Response treatments must be evaluated in a range of ecosystems to evaluate both their effectiveness at improving post-fire environmental conditions and counteracting desertification. In a study conducted throughout the west, the Burned Area Emergency Response treatment of using log erosion barriers was found to be ineffective at reducing erosion (Robichaud et al 2008). Although log erosion barriers were highly rated in professional surveys, they failed to provide adequate erosion prevention in storms with a >2 yr return period.…”

The Effects of Fire on the Function of the 200-BP-1 Engineered Surface Barrier

“…Under such conditions, the water drop can sit on the soil surface long enough to collapse, making it impossible to determine whether infiltration actually occurred. Robichaud et al (2008) reported success with a mini disk infiltrometer for determining wettability under such conditions. The two methods were compared at the 200-BP-1 barrier following the burn.…”