Hydrogeomorphic Recovery and Temporal Changes in Rainfall Thresholds for Debris Flows Following Wildfire

Hoch, Olivia; McGuire, Luke A.; Youberg, A.; Rengers, Francis K.

doi:10.1029/2021jf006374

Cited by 38 publications

(42 citation statements)

References 101 publications

(302 reference statements)

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“…Furthermore, the rate of recovery is fastest within the first year, suggesting that the hazard window likely primarily falls within the rainy season following fire within our study area before significant macropore growth at the Mini Disk scale. This is in line with recent estimates of post‐fire debris flow likelihood (Hoch et al., 2021). Implicit in this analysis is the assumption that the unburned field‐saturated hydraulic conductivity does not vary seasonally at the same magnitude as the burned sites, but we do not have sufficient data to address whether or not this is the case.…”

Section: Resultssupporting

confidence: 91%

Multi‐Stage Soil‐Hydraulic Recovery and Limited Ravel Accumulations Following the 2017 Nuns and Tubbs Wildfires in Northern California

et al. 2022

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California has recently entered an era of unprecedented wildfire risk, having experienced year-after-year of record-setting fires since 2015 (Goss et al., 2020). Continuing climate change is exacerbating the susceptibility of California's landscapes to wildfire, exposing new regions to extreme wildfire-prone weather conditions (Goss et al., 2020;Parks & Abatzoglou, 2020;Williams et al., 2019). Wildfire can act to reduce the saturated hydraulic conductivity of the surface soil (Martin & Moody, 2001), which can lead to an increased risk of hydrologic hazards such as flash floods (Malmon et al., 2007;Prosser & Williams, 1998) and debris flows (e.g., Kean et al., 2011). Additionally, burning of vegetation dams can release hillslope sediment as dry ravel (Florsheim et al., 1991), and the subsequent loading of this sediment to channels can increase debris-flow likelihood (DiBiase & Lamb, 2020).

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Section: Resultssupporting

confidence: 91%

Multi‐Stage Soil‐Hydraulic Recovery and Limited Ravel Accumulations Following the 2017 Nuns and Tubbs Wildfires in Northern California

et al. 2022

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“…Meanwhile, with the gradual restoration of vegetation after a fire, the properties of the hillslope surface soil will be improved and the soil permeability and erosion resistance will be enhanced. The hillslope runoff and erosion amount of the burned area will gradually decrease with time, thus reducing the susceptibility to PFDFs [2,25,28]. Figure 7 illustrates that the average of early cumulative erosion depth (ECE) increases while the PFDF occurrence frequency decreases with the increase of post-fire rainfall events (or time).…”

Section: Source Materials Distribution Smdmentioning

confidence: 99%

“…Wildfires can radically alter the vegetation cover and soil hydraulic properties in burned areas [1,2], burning the rainfall-intercepting canopy and leaf litter while decreasing the soil infiltration, and soil erosion resistance [2,4,24,25]. These effects are dominated by the severity of the wildfire, which is one of the key post-fire metrics affecting hillslope runoff, erosion, and PFDF generation.…”

Section: Introductionmentioning

confidence: 99%

“…In addition, the PFDF initiated by debris slide or hillslope runoff may persist for several years [27][28][29][30][31][32], which is associated with the recovery of vegetation and soil hydraulic properties [33,34]. Some recent scholars study the trend over time of these factors after the fire through model tests or simulations [2,25,35,36].…”

Section: Introductionmentioning

confidence: 99%

“…Of these prediction methods, the logistic regression (LR) method is the most ubiquitously used because it considers simple linear relationships, performs faster calculations, is easy to explain, and has been widely calibrated [7,8,37,44,45]. However, the majority of susceptibility prediction models only focus on spatial probability in the specific period while ignoring the time-related changes, such as soil permeability, soil erodibility, and other temporal factors, which will affect the recovery rate of post-fire watershed [2,[6][7][8]10,25]. The drawback is that the different period of PFDF susceptibility is unclear.…”

Section: Introductionmentioning

confidence: 99%

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Susceptibility Prediction of Post-Fire Debris Flows in Xichang, China, Using a Logistic Regression Model from a Spatiotemporal Perspective

Jin

Liu

et al. 2022

Remote Sensing

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The post-fire debris flow (PFDF) is a commonly destructive hazard that may persist for several years following the wildfires. Susceptibility mapping is an effective method for mitigating hazard risk. Yet, the majority of susceptibility prediction models only focus on spatial probability in the specific period while ignoring the change associated with time. This study improves the predictive model by introducing the temporal factor. The area burned by the 30 March 2020 fire in Xichang City, China is selected as an illustrative example, and the susceptibility of the PFDF was predicted for different periods of seven months after the wildfires. 2214 hydrological response events, including 181 debris flow events and 2033 flood events from the 82 watersheds are adopted to construct the sample dataset. Seven conditioning factors consist of temporal factors and spatial factors are extracted by the remote sensing interpretation, field investigations, and in situ tests, after correlation and importance analysis. The logistic regression (LR) is adopted to establish prediction models through 10 cross-validations. The results show that the susceptibility to PFDF has significantly reduced over time. After two months of wildfire, the proportions of very low, low, moderate, high, and very high susceptibility are 1.2%, 3.7%, 24.4%, 23.2%, and 47.6%, respectively. After seven months of wildfire, the proportions of high and very high susceptibility decreased to 0, while the proportions of very low to medium susceptibility increased to 35.4%, 35.6%, and 28.1%, respectively. The reason is that the drone seeding of grass seeds and artificial planting of trees accelerated the natural recovery of vegetation and soil after the fire. This study can give insight into the evolution mechanism of PFDF over time and reflect the important influence of human activity after the wildfire.

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Guidance for parameterizing post‐fire hydrologic models with in situ infiltration measurements

Liu

McGuire

Youberg

et al. 2023

Earth Surf Processes Landf

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Wildfire can alter soil‐hydraulic properties, often resulting in an increased prevalence of infiltration‐excess overland flow and greater potential for debris‐flow hazards. Mini disk tension infiltrometers (MDIs) can be used to estimate soil hydraulic properties, such as field‐saturated hydraulic conductivity (Kfs) and wetting front potential (Hf), and their spatial variability following wildfire. However, the small (point‐scale) footprint of MDI measurements makes it challenging to use these data to parameterize hydrologic models at the hillslope and watershed scales where hydrologic hazards, such as debris flows, initiate. Here, we designed numerical experiments to estimate spatially constant or watershed‐scale effective hydrologic parameters (EHPs) that approximate the response of spatially variable hydrologic parameters with distributions derived from MDI measurements at five sites in the southwestern United States. We found that it is possible to define EHPs for both Kfs and Hf based on the MDI measurements that lead to reasonable approximations of run‐off hydrographs at the outlets of small watersheds (<1 km2). We found that watershed EHPs are functions of rainfall characteristics, although they are most sensitive to rainfall intensity and relatively less sensitive to the temporal distribution of rainfall. EHPs are lower than the arithmetic mean of the MDI measurements and are better approximated by the median or geometric mean of the MDI measurements, particularly for storms with recurrence intervals of approximately 1 year or less that commonly initiate post‐fire debris flows. This work demonstrated that using the proposed upscaling method to estimate watershed‐scale EHPs, as opposed to approximating EHPs based on the arithmetic mean of the MDI measurements, improved the ability of a hydrologic model to identify storms that are likely to produce debris flows. Results improved our ability to link point‐scale MDI measurements and watershed‐scale EHPs in post‐fire settings and helped guide our ability to use MDI data to parameterize post‐fire hydrologic models.

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Hydrogeomorphic Recovery and Temporal Changes in Rainfall Thresholds for Debris Flows Following Wildfire

Abstract: Wildfires have become more frequent and severe in many different ecosystems and geographic regions, including the western United States (

Cited by 38 publications

References 101 publications

Multi‐Stage Soil‐Hydraulic Recovery and Limited Ravel Accumulations Following the 2017 Nuns and Tubbs Wildfires in Northern California

Multi‐Stage Soil‐Hydraulic Recovery and Limited Ravel Accumulations Following the 2017 Nuns and Tubbs Wildfires in Northern California

Susceptibility Prediction of Post-Fire Debris Flows in Xichang, China, Using a Logistic Regression Model from a Spatiotemporal Perspective

Guidance for parameterizing post‐fire hydrologic models with in situ infiltration measurements

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