Characterization of Environmental Seismic Signals in a Post-Wildfire Environment: Examples from the Museum Fire, AZ

Porter, R. C.; Joyal, Taylor; Beers, Rebecca; Youberg, A.; Loverich, Joseph; Schenk, Edward R.; Robichaud, Peter R.

doi:10.1002/essoar.10512638.1

Cited by 2 publications

(7 citation statements)

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“…Despite being subject to uncertainties, the observed positive correlations between PSD and flow discharge per channel width unit, and between PSD and flow depth suggest that seismic monitoring can effectively distinguish small and large events; in conjunction with the spectral content of seismic signals, this enabled us to investigate specific hydraulic parameters or physical processes within the flow. Taking four stream‐flow events as examples, the PSDs ranged from −141 to −136 dB, with their maximum frequency consistently being 81 Hz, attributed to sediment transport and water turbulence as well as raindrop impacts (e.g., Burtin et al., 2011; Porter et al., 2023). For hyperconcentrated‐flow and debris‐flow events, the enhancement of particle agitation caused by increasing discharge promoted the energy dissipation of channel flow via particle interactions with the channel bed.…”

Section: Resultsmentioning

confidence: 99%

“…This implies that both the relative amplitude of bedload‐ and grain‐collisional‐dominated seismic signals as well as the dominant frequencies of each process will decrease with increasing source‐to‐receiver distance. For instance, peak frequencies of debris‐flow seismic signals were observed at ∼30–40 Hz (Porter et al., 2023) and ∼7 Hz (Belli et al., 2022), corresponding to distances of 20 and 550 m, respectively.…”

Section: Discussionmentioning

confidence: 99%

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Characterization of Stream, Hyperconcentrated and Debris Flows from Seismic Signals: Insights into Sediment Transport Mechanisms and Flow Dynamics

Yang,

Chen,

et al. 2024

JGR Earth Surface

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Sediments in steep channels can be mobilized to form stream flows, hyperconcentrated flows and debris flows, which can cause damage to downstream communities. However, the understanding of the sediment‐transport mechanisms that control these processes remains incomplete due to the lack of effective monitoring methods. In this study, we utilize seismic data captured during these sediment‐laden flows through field experiments and in situ monitoring to offer insights into flow mechanics and sediment transport mechanisms. Results show that sediment transport in stream flows and hyperconcentrated flows is primarily supported by viscous shear and turbulent stresses, whereas grain collisional stresses play a significant role in debris‐flow dynamics. By characterizing impact rates, basal impulses and flow discharge, seismic monitoring can reveal the internal flow dynamics and bulk flow characteristics as well as the characteristics of sediment transport. Increasing solid concentrations can elicit positive nonlinearities in the frequency‐based scaling relationships between seismic power and hydrographs, indicating transitions in the seismic signal from turbulence‐bedload‐dominated to bedload‐dominated, and grain collisional‐dominated regimes. By introducing the ratio of the real shear stress to the critical shear stress, we refined the phase space for sediment stability. Combining this criterion with the absolute seismic power enables us to establish ground‐motion thresholds for distinguishing different flow types. Our results highlight opportunities to use seismic data for the quantitative inversion of these fluvial processes and debris flows as well as early warning strategies.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Characterization of Stream, Hyperconcentrated and Debris Flows from Seismic Signals: Insights into Sediment Transport Mechanisms and Flow Dynamics

Yang,

Chen,

et al. 2024

JGR Earth Surface

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“…The Flagstaff region saw record low summer monsoonal rain in 2019 and 2020 with no substantial postfire impacts. Initial flooding occurred during the above average summer monsoon season of 2021, resulting in several debris flows high within the Museum Fire watershed and four significant floods (Porter et al 2021;Porter et al 2023;Schenk et al 2023). Post-fire flooding resulted in vast amounts of sedimentation in downstream residential areas as existing drainage features and channels were 95 overwhelmed with sediment and debris.…”

Section: Study Sitementioning

confidence: 99%

“…Initial flood modeling was completed at a 20-foot (6m) grid scale using 2015 lidar elevation data, subsequent modeling was completed at a 5 foot (1.8m) grid scale using a fall 2019 lidar elevation dataset. All modeling indicates an approximate 10 to 100 times (one to two orders of magnitude) increase in runoff depending on rain event; more information on hydrologic conditions is provided in a conference proceedings paper (Schenk et al 2023). 110 Sediment modeling focused on quantifying relative sediment sources relating to channel and hillslope erosional processes.…”

Section: Flood Flow Modelingmentioning

confidence: 99%

“…The Modified Universal Soil Loss Equation (MUSLE; Williams and Benhardt 1977) is utilized to estimate sediment supply from hillslopes during specific precipitation events. Discharges for these events were estimated by JE Fuller, Inc as part of their post flood modeling efforts (JE Fuller 2019; Schenk et al 2023). The MUSLE estimates are provided here as a reference point for larger events.…”

Section: Sediment Modelingmentioning

confidence: 99%

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Post-wildfire sediment source and transport modeling, empirical observations, and applied mitigation: an Arizona USA case study

Schenk,

Wood,

Haden

et al. 2023

Preprint

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Abstract. Post-wildfire floods are receiving greater attention as wildland-urban interfaces become more common and as catastrophic wildfires have increased in frequency. Sediment sourcing, transport, and deposition in the post-fire environment receive attention due to the severity of risk caused by debris flows and concentrated sediment flood flows. This study provides a series of sediment model predictions based on MUSLE and the WARSSS suite of models that included: ERMIT, BANCS, and FLOWSED/POWERSED for the 2019 Museum Fire (809 Ha of steep slope Pinus ponderosa forest in the Spruce Wash watershed). A comparison is provided for the internet-based WEPPcloud post-fire sediment model. Empirical evidence from four floods in 2021 indicated 9,900 Mg of sediment yield to city of Flagstaff neighborhoods, the WEPP model estimated 3870 Mg/year, MUSLE predicted 4860 Mg/year (based on the four events), and the WARSSS suite of models predicted 4630 Mg/year. Both WEPP and WARSSS estimated more sediment yield from channels than hillslope (51 %/49 % and 60 %/40 % respectively) though the spatial patterns differ between the models. Sediment mitigation structures, or “work areas”, are discussed as real-world applications of sediment forecasting for reducing downstream impacts. Continued revisions of sediment forecasts, based on case studies such as this one, can provide managers and policy makers with tools for risk mitigation and emergency management.

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Characterization of Environmental Seismic Signals in a Post-Wildfire Environment: Examples from the Museum Fire, AZ

Cited by 2 publications

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Characterization of Stream, Hyperconcentrated and Debris Flows from Seismic Signals: Insights into Sediment Transport Mechanisms and Flow Dynamics

Characterization of Stream, Hyperconcentrated and Debris Flows from Seismic Signals: Insights into Sediment Transport Mechanisms and Flow Dynamics

Post-wildfire sediment source and transport modeling, empirical observations, and applied mitigation: an Arizona USA case study

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