The Influence of Large Woody Debris on Post-Wildfire Debris Flow Sediment Storage

Rengers, Francis K.; McGuire, Luke A.; Barnhart, Katherine R.; Youberg, A.; Cadol, Daniel; Gorr, Alexander; Hoch, Olivia; Beers, Rebecca; Kean, Jason W.

doi:10.5194/egusphere-2022-1398

Cited by 1 publication

(2 citation statements)

References 35 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Vegetation is dominated by ponderosa pine (Pinus ponderosa), and the area is underlain by tertiary-aged volcanic rocks (Scholle, 2003). Dominant soil types include Mollisols, Inceptisols, and Alfisols, and the soil texture is classified as a loam (43 % sand, 45 % silt, 12 % clay) (Rengers et al, 2023). Rainfall at the site occurs primarily during the summer, as part of the North American monsoon, as well as during the winter months.…”

Section: Study Areamentioning

confidence: 99%

See 1 more Smart Citation

Characteristics of debris-flow-prone watersheds and debris-flow-triggering rainstorms following the Tadpole Fire, New Mexico, USA

McGuire,

Rengers,

Youberg

et al. 2024

Nat. Hazards Earth Syst. Sci.

View full text Add to dashboard Cite

Abstract. Moderate- or high-severity fires promote increases in runoff and erosion, leading to a greater likelihood of extreme geomorphic responses, including debris flows. In the first several years following fire, the majority of debris flows initiate when runoff rapidly entrains sediment on steep slopes. From a hazard perspective, it is important to be able to anticipate when and where watershed responses will be dominated by debris flows rather than flood flows. Rainfall intensity averaged over a 15 min duration, I15, in particular, has been identified as a key predictor of debris flow likelihood. Developing effective warning systems and predictive models for post-fire debris flow hazards therefore relies on high-temporal resolution rainfall data at the time debris flows initiate. In this study, we documented the geomorphic response of a series of watersheds following a wildfire in western New Mexico, USA, with an emphasis on constraining debris flow timing within rainstorms to better characterize debris-flow-triggering rainfall intensities. We estimated temporal changes in soil hydraulic properties and ground cover in areas burned at different severities over >2 years to offer explanations for observed differences in spatial and temporal patterns in debris flow activity. We observed 16 debris flows, all of which initiated during the first several months following the fire. The average recurrence interval of the debris-flow-triggering I15 is 1.3 years, which highlights the susceptibility of recently burned watersheds to runoff-generated debris flows in this region. All but one of the debris flows initiated in watersheds burned primarily at moderate or high soil burn severity. Since soil hydraulic properties appeared to be relatively resilient to burning, we attribute reduced debris flow activity at later times to decreases in the fraction of bare ground. Results provide additional constraints on the rainfall characteristics that promote post-fire debris flow initiation in a region where fire size and severity have been increasing.

show abstract

Section: Study Areamentioning

confidence: 99%

“…The two geophones in watershed A were installed outside of the channel, roughly 15 m from the channel thalweg, and were separated by approximately 18 m (Rengers et al, 2023). Geophone data were filtered between 5 and 20 Hz, and the instrument response was removed, converting the signal to ground velocity.…”

Section: Rainfall and Flow Monitoringmentioning

confidence: 99%