Nina Zazali: Dynamics approach to understanding forest fuel accumulation
Commenced: February 2017 Expected completion: May 2022
Forest fuel dynamics play a critical role in the flammability of fire-prone ecosystems. Of prime importance are the surface, near-surface and elevated fuels present in a forest stand. These fuels are typically comprised of dead materials, such as leaves, twigs, bark, and grasses, which are deposited at the surface or suspended just above it, or live materials such as shrubs and young saplings. As a result, these interactions create a pool of complex fuel load structures as fuel elements largely determine the fire rate of spread and intensity, as well as its potential to exhibit more extreme fire behaviours, such as spotting and crown fire propagation. Moreover, the amount of fuel available depends on the balance between the rate at which fuels are deposited or grow, and the rate they decompose or senesce.
Therefore, my PhD work presents several novel approaches to account for high-level reflection of complex vegetation interactions and the overall fuel accumulation over time. The underlying presented models reflect ecological reality from a mathematical modelling perspective by demonstrating different interactions between age classes of a species and between multiple species of vegetation. The work also accommodates analysis of instantaneous fire disturbances, such as wildfire or prescribed burns. This approach is illustrated by incorporating the Dirac delta function to account for the rapid removal of fuels and its outcomes on vegetation regeneration. We may be able to validate the model capability by incorporating these mathematical frameworks with ground truth data analysis in assimilating complex forest ecosystems. Thus, this initiated study allows for a better understanding of the relationship between fuel availability and its implication for fire risks and ecological fire management.
Tanvir Saurav: Simulation of ember storms
Commenced: February 2022, expected completion February 2026
Embers have been identified as the leading cause of house loss in previous fire events. Near the wildland–urban interface (WUI), areas where structures and developments meet wildland, embers pose a greater risk as small ember particles can flow over roads and terrain into properties, increasing the likelihood of structure damage. Although recent computational works have provided a significant insight into ember transport, the current models do not capture the near-ground behaviour and transportation of embers, and the entrainment (the process through which near-ground particles are introduced into the flow) of embers from the ground, both of which are key factors in ember storms. This project aims to improve current ember modelling to capture near-ground entrainment and relofting by analysing and adapting existing particle transport models and applying them to model ember storms using large eddy simulation (LES) in Nek5000, a popular spectral element solver. The implementation of these models will help develop more robust simulation techniques. This will ensure that authorities are better equipped to deal with wildfires at the WUI and formulate better mitigation strategies.
Sahar Masoudian: Stochastic modelling of bushfire spread
Commenced: August 2020, expected completion date August 2024
This project addresses the important problem of incorporating environmental uncertainty in bushfire propagation modelling. To faithfully capture a range of uncertainties related to environmental inputs (in particular wind velocity) in bushfire propagation models, it is important to incorporate the stochastic nature of these inputs. In this research project, wind is modelled using stochastic processes in an attempt to achieve more reliable bushfire spread predictions compared to other probabilistic approaches. Two-dimensional bushfire propagation can be modelled using the level set method, and environmental uncertainty can be incorporated either directly into the bushfire spread model or by extending the propagation model to a stochastic level set approach. Stochastic bushfire simulations are compared to experimental fire spread data collected as part of broader international collaboration.
Jyoteesh reddy Papari: Heatwaves and compounding drought-heatwaves in Australia: historical changes, association with ENSO and IOD, and influence on bushfire fuels
Commenced: Aug 2019 expected completion date June 2022
The primary objective of this project is: To examine historical changes in Australian heatwaves and heatwave-drought compounds, investigate ENSO and IOD effects on them, and explore their relationship with bushfire fuels. Firstly, the historical changes in Australian heatwaves are analysed from a multidimensional perspective using various observational datasets. Results suggest that heatwaves are getting worse in terms of frequency, duration, intensity, season length, and spatial extent during recent decades over Australia. Secondly, the association of tropical climate variability modes (ENSO and IOD) with heatwaves and compound drought and heatwaves (CDHWs) in Australia is examined using the single model initial-condition large ensembles. We found that the strong El Niño (Es) and strong El Niño co-occurring with strong IOD positive (EsIPs) seasons favour the large contiguous heatwaves in Australia. Furthermore, results show that an extreme CDHW season in terms of frequency and severity occurs one out of every two seasons of Es (EsIPs) over Australia's northeast (northeast and southeast). Lastly, the relationship between heatwave characteristics and mean dead fine fuel moisture content and the influence of drought on their association is investigated over southeast Australia during the peak heat and fire seasons. This relationship varies among different heatwave characteristics and regions and is modulated by drought conditions.
Wenyuan Ma: Understanding the geographical factors influencing pyroCb development and risk.
Commencement date: May 2021 Expected completion date: May 2025
Extreme wildfires can produce pyrocumulonimbus (pyroCb) storms, which impact not only the surface but also extend their influence high into the atmosphere. The overarching aim of this research project is to provide insights into the geographical patterns of pyroCb occurrence and practical guidance for wildfire management, now and into the future. The main research objectives are: (1) to better understand the drivers of pyroCb development and their impact mechanisms, to quantify the relative contributions of these drivers, and to investigate the geographical differences in these drivers and their impacts at the large scale; (2) to quantify pyroCb risk and develop models to predict the longer-term probability of pyroCb occurrence; (3) to understand the temporal and spatial patterns of pyroCb occurrences in Australia, investigate how these patterns might change under future climate projections, and to map the longer-term risks of pyroCb in Australia. This work forms part of an ongoing international collaboration on pyroCb research.
Ali Edalati-nejad: The effect of fuel moisture content on the spread rate of bushfire in the presence of wind and slope.
Commenced: Feb. 2022 expected completion date Feb. 2026
Understanding the interactive effect of live and dead fuel moisture content (FMC), wind, and terrain slope is a key challenge in wildfire science. This research employs the techniques of Computational Fluid Dynamics (CFD) to model flame propagation and bushfire spread, using a full three-dimensional simulation, with a Large Eddy Simulation (LES) turbulence model, combining the effect of fuel moisture content, wind-fire interaction, terrain slope, and radiative heat transfer. The project will improve the knowledge and ability to alleviate environmental problems and will contribute to the better management of bushfires and mitigate their hazards in real inhomogeneous landscapes that contain a mixture of live and dead fuels.
Caleb Wilson: Meteorological drivers of pyrocumulonimbus in Australia
Start date: September 2021 Expected completion date: September 2025
This project aims to investigate specific meteorological factors responsible for the formation of pyrocumulonimbus (pyroCb/ firestorms) associated with bushfires in Australia. The presence of a pyroCb is an indication that a bushfire has become coupled with the atmosphere, and the resulting feedbacks between the fire at the surface and the storm above may lead to unpredictable and extremely dangerous conditions (both in terms of fire behaviour and storm behaviour) for anyone nearby.
Previous research has shown that meteorological factors of pyroCb formation may include—but are likely not limited to—the overspreading of a conditionally unstable airmass over ongoing fires with surface conditions favorable for extreme fire behavior, cold front and pre-frontal trough interactions with intensely burning fires, thunderstorm outflow boundary and sea breeze interactions with ongoing fires, and gravity wave interactions with ongoing fires. Nearly all previous research has focused on fires which resulted in pyroCb formation, while very little research has been conducted to differentiate fires which resulted in pyroCb formation from fires which did not.
This project will use the Weather Research and Forecasting-Fire model (WRF-Fire) to examine specific instances of pyroCb formation and non-formation in Australia. In particular, we are interested in events where one bushfire resulted in pyroCb formation, while another nearby fire did not. We aim to discover what differences (meteorological or otherwise) existed at the given locations of the fires and how that may have induced or inhibited pyroCb formation.