@article {bnh-7761, title = {The influence of soil moisture on surface and sub-surface litter fuel moisture simulation at five Australian sites}, journal = {Agricultural and Forest Meteorology}, volume = {298-299}, year = {2021}, month = {03/2021}, abstract = {

Fuel moisture content (FMC) of the litter is a critical factor determining fire ignition and spread and is an important input for most fire behaviour prediction models. Several models, ranging from empirical regression functions to physics-based models, have been developed to forecast litter FMC. Soil moisture below the litter layer has been shown to influence litter FMC, but few models explicitly consider its effect. This study aimed to evaluate how soil moisture content may affect litter FMC by coupling soil moisture as a boundary condition to the physics-based {\textquoteleft}Koba{\textquoteright} model, which simulates radiation, energy and moisture fluxes in the surface and subsurface litter layer. The coupled model was tested at five sites in Victoria, Australia, where litter FMC values were recorded continuously during 2014-2015 using calibrated fuel stick sensors. Two versions of the model were compared against the observations: an uncoupled model and a model version accounting for the vapour flux from soil to litter. The simulation results show that the influence of soil moisture depends on environmental conditions. Soil moisture appeared to have a minor influence on FMC when both soil and litter are dry, but a stronger influence when the soil is relatively wet. Correspondingly, the coupled model explained observed FMC better than the uncoupled model for the two wetter study sites. As expected, the subsurface litter in contact with the soil appeared more sensitive to soil moisture conditions than the surface litter. The influence of soil vapour flux on litter FMC can be considerable during the transition from wet to dry litter and soil conditions. This has implications for hazard reduction burning, which is typically planned to take advantage of transitional fuel moisture conditions. Further research is needed to understand the influence of the structure and thickness of litter on the importance of soil vapour flux.

}, keywords = {Coupled model, Dead fuel, forecast, fuel moisture content, Soil moisture}, doi = {https://doi.org/10.1016/j.agrformet.2020.108282}, url = {https://www.sciencedirect.com/science/article/abs/pii/S0168192320303841?dgcid=coauthor}, author = {Li Zhao and Marta Yebra and Albert van Dijk and Geoffrey J. Cary and Stuart Matthews and Gary J. Sheridan} } @article {bnh-7475, title = {Exploring the key drivers of forest flammability in wet eucalypt forests using expert-derived conceptual models}, journal = {Landscape Ecology}, volume = {35}, year = {2020}, month = {06/2020}, pages = {1775{\textendash}1798}, abstract = {

Context

Fire behaviour research has largely focused on dry ecosystems that burn frequently, with far less attention on wetter forests. Yet, the impacts of fire in wet forests can be high and therefore understanding the drivers of fire in these\ systems\ is vital.

Objectives

We sought to identify and rank by importance the factors plausibly driving flammability in wet eucalypt forests, and describe relationships between them. In doing so, we formulated a set of research priorities.

Methods

Conceptual models of forest flammability in wet eucalypt forests were elicited from 21 fire experts using a combination of elicitation techniques. Forest flammability was defined using fire occurrence and fireline intensity as measures of ignitability and heat release rate, respectively.

Results

There were shared and divergent opinions about the drivers of flammability in wet eucalypt forests. Widely agreed factors were drought, dead fine fuel moisture content, weather and topography. These factors all influence the availability of biomass to burn, albeit their effects and interactions on various dimensions of flammability are poorly understood. Differences between the models related to lesser understood factors (e.g. live and coarse fuel moisture, plant traits, heatwaves) and the links between factors.

Conclusions

By documenting alternative conceptual models, we made shared and divergent opinions explicit about flammability in wet forests. We identified four priority research areas: (1) quantifying drought and fuel moisture thresholds for fire occurrence and intensity, (2) modelling microclimate in dense vegetation and rugged terrain, (3) determining the attributes of live vegetation that influence forest flammability, (4) evaluating fire management strategies.

}, keywords = {Cognitive mapping, Conceptual models, Expert elicitation, Fire behaviour, fire intensity, flammability, Structured decision-making, Structured expert judgement, Wet forest, Wildfire}, doi = {https://doi.org/10.1007/s10980-020-01055-z}, url = {https://link.springer.com/article/10.1007/s10980-020-01055-z}, author = {Jane Cawson and Victoria Hemming and Ackland, A and Wendy R. Anderson and David Bowman and Ross Bradstock and Brown, T and Jamie Burton and Geoffrey J. Cary and Thomas Duff and Alex Filkov and Furlaud, James M. and Tim Gazzard and Kilinc, Musa and Petter Nyman and Ross Peacock and Mike Ryan and Jason J. Sharples and Gary J. Sheridan and Tolhurst, K.G. and Tim Wells and Phil Zylstra and Trent Penman} } @conference {bnh-6531, title = {Probability and consequence of post-fire contamination events in a water supply catchment}, booktitle = {AFAC19 powered by INTERSCHUTZ - Bushfire and Natural Hazards CRC Research Forum}, year = {2019}, month = {12/2019}, publisher = {Australian Institute for Disaster Resilience}, organization = {Australian Institute for Disaster Resilience}, address = {Melbourne}, abstract = {

Large cities around the world source their drinking water from forested catchments, which deliver water that is treatable at minimal costs.

These forests are often prone to wildfire, which tend to increase surface runoff, destabilize soils and trigger increased sediment delivery into water supply systems. The consequences of wildfire for water supply are a significant concern, with the potential for extended periods of water supply disruption, increased water treatment cost, and a demand for catchment restoration and investment in expensive treatment infrastructure. Moreover, with climate change, the likelihood of wildfire is increasing in many forest ecosystems making water supply systems increasingly exposed to post-wildfire contamination.

There are numerous uses for models that predict water quality impacts. On an operational level, models that reveal spatial variation in the erosion susceptibility provide catchment managers with a means to prioritize risk mitigation through fuel reduction or post-wildfire response. In such cases, spatial mapping of erosion risk in a relative sense may be sufficient to provide effective tools for allocating resources and mitigating risk in the areas of the catchment that are most likely to be producing sediment. When developing strategic plans and making decisions about the future management of a water resource, the demands on predictive models increase. For instance, a water supply agency may want to determine if there is a case for upgrading water treatment capability or adjusting the water supply network to reduce the likelihood of water supply interruptions due to wildfires. In this setting, a detailed understanding of risk is required for cost-benefit analysis to inform decisions about such investments.

In this study we are motivated by the need amongst water supply managers to know {\textquoteleft}For how long is it likely that my reservoir will be offline due to contamination by post-wildfire erosion?{\textquoteright}. In addressing this question, we seek to provide the means for developing policy and investment strategies within environmental management frameworks that are underpinned by economics and risk. The specific objective of the study is to model how frequency and magnitude of erosion in headwaters translates to probability and duration of water contamination exceeding treatability thresholds at the water offtake. In this study we only consider sediment in our risk model because treatment facilities are often highly vulnerable to turbidity caused by suspended sediment.

Our paper outlines a parameter-reduction approach whereby empirical transfer functions are used to link a probabilistic model of sediment delivery from burned headwaters and a reservoir hydrodynamic model. With these transfer functions we produce a direct measure of risk (i.e. probability of consequence) and discuss practical questions around potential cost of the wildfire threat to water supply agencies and the capacity for catchment managers to mitigate such costs. Furthermore, we use the model to evaluate how different model components contribute to uncertainty in risk.

Download the full non-peer reviewed research proceedings\ from the Bushfire and Natural Hazards CRC Research Forumhere.

}, keywords = {erosion risk, fire impacts, fire severity, risk management, water supply}, url = {https://knowledge.aidr.org.au/resources/australian-journal-of-emergency-management-monograph-series/}, author = {Petter Nyman and Peter Yeates and Christoph Langhans and Philip J. Noske and Shane Haydon and Gary J. Sheridan} } @conference {bnh-3897, title = {Implementing CRC research: development of a tool for assessing post-fire hydrologic risk}, booktitle = {AFAC17}, year = {2017}, month = {09/2017}, publisher = {Bushfire and Natural Hazards CRC}, organization = {Bushfire and Natural Hazards CRC}, address = {Sydney}, abstract = {

An output of the Bushfire CRC was the development of methods for assessing post-fire hydrologic risks to human life, infrastructure, and water quality. The work was delivered as part of the Fire in the Landscape research theme and built on many years of research conducted by the Forest Hydrology research group at the University of Melbourne in collaboration with the Bushfire CRC, Melbourne Water and DELWP.

The Bushfire CRC project was identified for research utilisation by CRC end-users and a face-to-face meeting between end-users, researchers and AFAC research utilisation staff was arranged. The meeting resulted in the development of a three phase research utilisation plan. The first phase was a nationwide assessment of hydrologic risk related to wildfire and the development of a set of national guidelines based on general principles. This work was resourced by AFAC and delivered in 2014. Phase two was managed by ACT Parks and Conservation Service and aimed at advancing the generalised risk guidelines developed for AFAC and applying them to ACT catchments. This was completed in 2016 with the delivery of a suite of GIS tools that built on the algorithms that were developed for the Bushfire Rapid Risk Assessment Teams in Victoria.\  Additional research - phase three - could parameterise models for specific catchments, with the aim of delivering quantitative information on the probability and magnitude of post-fire erosion.

The project has generated some lessons about the research utilisation process:

  1. End-users must be clear about what they need and have a sound technical understanding of the research.
  2. All parties need to have a common picture of what is to be developed and how it is to be used.
  3. Researchers should be prepared to synthesise their work such that the complexity of processes does not impede the development of practical tools.
}, author = {Adam J. Leavesley and Petter Nyman and Noreen Krusel and Gary J. Sheridan and Neil Cooper} } @article {bnh-2749, title = {Predicting sediment delivery from debris flows after wildfire}, journal = {Geomorphology}, volume = {250}, year = {2015}, month = {12/2015}, chapter = {173}, abstract = {

Debris flows are an important erosion process in wildfire-prone landscapes. Predicting their frequency and magnitude can therefore be critical for quantifying risk to infrastructure, people and water resources. However, the factors contributing to the frequency and magnitude of events remain poorly understood, particularly in regions outside western USA. Against this background, the objectives of this study were to i) quantify sediment yields from post-fire debris flows in southeast Australian highlands and ii) model the effects of landscape attributes on debris flow susceptibility. Sediment yields from post-fire debris flows (113{\textendash}294\ t\ ha-\ 1) are 2{\textendash}3 orders of magnitude higher than annual background erosion rates from undisturbed forests. Debris flow volumes ranged from 539 to 33,040 m3\ with hillslope contributions of 18{\textendash}62\%. The distribution of erosion and deposition above the fan were related to a stream power index, which could be used to model changes in yield along the drainage network. Debris flow susceptibility was quantified with a logistic regression and an inventory of 315 debris flow fans deposited in the first year after two large wildfires (total burned area\ =\ 2919 km2). The differenced normalised burn ratio (dNBR\ or burn severity), local slope, radiative index of dryness (AI) and rainfall intensity (from rainfall radar) were significant predictors in a susceptibility model, which produced excellent results in terms identifying channels that were eroded by debris flows (Area Under Curve,\ AUC\ =\ 0.91). Burn severity was the strongest predictor in the model (AUC\ =\ 0.87 when\ dNBR\ is used as single predictor) suggesting that fire regimes are an important control on sediment delivery from these forests. The analysis showed a positive effect of\ AI\ on debris flow probability in landscapes where differences in moisture regimes due to climate are associated with large variation in soil hydraulic properties. Overall, the results from this study based in the southeast Australian highlands provide a novel basis upon which to model sediment delivery from post-fire debris flows. The modelling approach has wider relevance to post-fire debris flow prediction both from risk management and landscape evolution perspectives.

}, url = {http://www.sciencedirect.com/science/article/pii/S0169555X15301355}, author = {Petter Nyman and Smith, Hugh G. and Christopher Sherwin and Christoph Langhans and Lane, Patrick N. J. and Gary J. Sheridan} } @article {BF-4256, title = {Hydro-geomorphic response models for burned areas and their applications in land management}, journal = {Progress in Physical Geography}, volume = {37}, year = {2013}, month = {12/2013}, pages = {787 - 812}, issn = {0309-1333}, doi = {10.1177/0309133313508802}, author = {Petter Nyman and Gary J. Sheridan and Lane, Patrick N. J.} } @article {BF-4259, title = {Sediment availability on burned hillslopes}, journal = {Journal of Geophysical Research: Earth Surface}, year = {2013}, month = {12/2013}, pages = {n/a - n/a}, doi = {10.1002/jgrf.20152}, url = {http://onlinelibrary.wiley.com/doi/10.1002/jgrf.20152/abstract}, author = {Petter Nyman and Gary J. Sheridan and Moody, John A. and Smith, Hugh G. and Philip J. Noske and Lane, Patrick N. J.} } @proceedings {BF-4367, title = {Water Quality Risk Due to Fire Disturbance: Tools for Quantifying}, year = {2013}, url = {http://www.bushfirecrc.com/resources/research-report/water-quality-risk-due-fire-disturbance-tools-quantifying}, author = {Petter Nyman and Gary J. Sheridan and Owen D. Jones and Lane, Patrick N. J. and Christopher Sherwin and Philip J. Noske and Rene van der Sant} } @proceedings {BF-3044, title = {The effect of prescribed fire severity}, year = {2011}, month = {2011}, publisher = {Bushfire CRC}, address = {Sydney, Australia}, isbn = {978-0-9806759-9-3}, url = {http://www.bushfirecrc.com/resources/pages-105-119-effect-prescribed-fire-severity}, author = {cawson, J. G and Gary J. Sheridan and Smith, Hugh G. and Lane, Patrick N. J.} } @proceedings {BF-3048, title = {Erosion and risk to water resources in the context of fire and rainfall regimes}, year = {2011}, publisher = {R.P. Thornton (Ed) 2011, {\textquoteleft}Proceedings of Bushfire CRC \& AFAC 2010 Conference Science Day{\textquoteright} 1 September 2011, Sydney Australia, Bushfire CRC}, address = {Sydney, Australia}, issn = {978-0-9806759-9-3}, author = {Petter Nyman and Gary J. Sheridan and Owen D. Jones and Lane, Patrick N. J.} }