Fire, Flood, and Drought: Extreme Climate Events Alter Flow Paths and Stream Chemistry

Murphy, Sheila F.; McCleskey, R. Blaine; Martin, Deborah A.; Writer, Jeffrey H.; Ebel, Brian A.

doi:10.1029/2017jg004349

Cited by 58 publications

(58 citation statements)

References 70 publications

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“…The sampling approach, whereby samples were collected at regular intervals, may have missed important events that occurred between sampling campaigns. The wildfire signals in water quality parameters are often tightly coupled to the runoffgenerating mechanism (Murphy et al 2018). A more targeted event-based water quality sampling regime and hillslope erosion experiment are needed to obtain more robust estimates of fire impact water quality parameters.…”

Section: Discussionmentioning

confidence: 99%

Assessment of post-wildfire erosion risk and effects on water quality in south-western Australia

Blake

Nyman

Nice

et al. 2020

Int. J. Wildland Fire

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Investigations of wildfire impact on water resources have escalated globally over the last decade owing to an awareness of climate-related vulnerabilities. Within Australia, research into post-wildfire erosion has focused on water supply catchments in the south-eastern region. Here, we examine post-wildfire erosion risk and its potential for water quality impacts in a catchment in south-western Australia. The catchment of the Harvey River, which drains from forested escarpments onto an agricultural coastal plain and into valuable coastal wetlands, was burnt by wildfire in 2016. The aims of this study were to determine erosion risk across contrasting landforms and variable fire severity, using the Revised Universal Soil Loss Equation (RUSLE), and to determine whether post-fire water quality impacts could be detected at permanent river monitoring stations located on the coastal plain. RUSLE outputs showed erosion hot-spots at intersections of steep terrain and high fire severity and that these areas were confined to forested headwaters and coastal dunes. Monthly water quality data showed conspicuous seasonal patterns, but that sampling frequency was temporally too coarse to pick up predicted event-related effects, particularly given that the pre-existing monitoring sites were distal to the predicted zone of contamination.

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Section: Discussionmentioning

confidence: 99%

Assessment of post-wildfire erosion risk and effects on water quality in south-western Australia

Blake

Nyman

Nice

et al. 2020

Int. J. Wildland Fire

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“…Erosion and deposition through drainage networks has large implications for how debris flows translate to impacts on downstream water resources (Bladon et al, ; Murphy et al, ). Langhans et al .…”

Section: Introductionmentioning

confidence: 99%

Debris‐flow‐dominated sediment transport through a channel network after wildfire

Nyman

Box

Stout

et al. 2020

Earth Surf Processes Landf

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Field studies that investigate sediment transport between debris‐flow‐producing headwaters and rivers are uncommon, particularly in forested settings, where debris flows are infrequent and opportunities for collecting data are limited. This study quantifies the volume and composition of sediment deposited in the arterial channel network of a 14‐km2 catchment (Washington Creek) that connects small, burned and debris‐flow‐producing headwaters (<1 km2) with the Ovens River in SE Australia. We construct a sediment budget by combining new data on deposition with a sediment delivery model for post‐fire debris flows. Data on deposits were plotted alongside the slope–area curve to examine links between processes, catchment morphometry and geomorphic process domains. The results show that large deposits are concentrated in the proximity of three major channel junctions, which correspond to breaks in channel slope. Hyperconcentrated flows are more prominent towards the catchment outlet, where the slope–area curve indicates a transition from debris flow to fluvial domains. This shift corresponds to a change in efficiency of the flow, determined from the ratio of median grain size to channel slope. Our sediment budget suggests a total sediment efflux from Washington Creek catchment of 61 × 103 m3. There are similar contributions from hillslopes (43 ± 14 × 103 m3), first to third stream order channel (35 ± 12 × 103 m3) and the arterial fourth to fifth stream order channel (31 ± 17 × 103 m3) to the total volume of erosion. Deposition (39 ± 17 × 103 m3) within the arterial channel was higher than erosion (31 ± 17 × 103 m3), which means a net sediment gain of about 8 × 103 m3 in the arterial channel. The ratio of total deposition to total erosion was 0.44. For fines <63 μm, this ratio was much smaller (0.11), which means that fines are preferentially exported. This has important implications for suspended sediment and water quality in downstream rivers. © 2019 John Wiley & Sons, Ltd.

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“…Depending on the sequence of post‐fire rain storms, higher overland flow from hillslopes can either erode channel banks and beds where there is a lack of previously stored sediments available for transport or cause aggradation in channels when flow is not high enough to transport all sediment downstream (Brogan et al, 2019; Kampf et al, 2016; Moody & Martin, 2009). Upstream‐to‐downstream sediment connectivity may be greater for rainfall events with high total depths and following high antecedent rainfall, as these conditions increase runoff and sediment transport capacity of streams (Moody & Martin, 2001a, 2001b; Murphy et al, 2018; Wilson et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

Connectivity of post‐fire runoff and sediment from nested hillslopes and watersheds

Wilson

Kampf

Ryan

et al. 2020

Hydrological Processes

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Wildfire increases the potential connectivity of runoff and sediment throughout watersheds due to greater bare soil, runoff and erosion as compared to pre‐fire conditions. This research examines the connectivity of post‐fire runoff and sediment from hillslopes (<1.5 ha; n = 31) and catchments (<1000 ha; n = 10) within two watersheds (<1500 ha) burned by the 2012 High Park Fire in northcentral Colorado, USA. Our objectives were to: (1) identify sources and quantify magnitudes of post‐fire runoff and erosion at nested hillslopes and watersheds for two rain storms with varied duration, intensity and antecedent precipitation; and (2) assess the factors affecting the magnitude and connectivity of runoff and sediment across spatial scales for these two rain storms. The two summer storms that are the focus of this research occurred during the third summer after burning. The first storm had low intensity rainfall over 11 hours (return interval <1–2 years), whereas the second event had high intensity rainfall over 1 hour (return interval <1–10 years). The lower intensity storm was preceded by high antecedent rainfall and led to low hillslope sediment yields and channel incision at most locations, whereas the high intensity storm led to infiltration‐excess overland flow, high sediment yields, in‐stream sediment deposition and channel substrate fining. For both storms, hillslope‐to‐stream sediment delivery ratios and area‐normalised cross‐sectional channel change increased with the percent of catchment that burned at high severity. For the high intensity storm, hillslope‐to‐stream sediment delivery ratios decreased with unconfined channel length (%). The findings quantify post‐fire connectivity and sediment delivery from hillslopes and streams, and highlight how different types of storms can cause varying magnitues and spatial patterns of sediment transport and deposition from hillslopes through stream channel networks.

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Fire, Flood, and Drought: Extreme Climate Events Alter Flow Paths and Stream Chemistry

Cited by 58 publications

References 70 publications

Assessment of post-wildfire erosion risk and effects on water quality in south-western Australia

Assessment of post-wildfire erosion risk and effects on water quality in south-western Australia

Debris‐flow‐dominated sediment transport through a channel network after wildfire

Connectivity of post‐fire runoff and sediment from nested hillslopes and watersheds

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