@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 {bnh-1842, title = {Trends in evapotranspiration and streamflow following wildfire in resprouting eucalypt forests}, journal = {Journal of Hydrology}, volume = {524}, year = {2015}, month = {05/2015}, pages = {614-624}, chapter = {614}, abstract = {

The objective of this study was to estimate the recovery trajectory of evapotranspiration (Et) and streamflow (Q) in resprouting forested catchments following wildfire. Recovery dynamics were assessed in mixed species eucalypt forests in south-eastern Australia which recover from disturbance largely via vegetative resprouting, and to a lesser degree, via seedling recruitment. Changes in\ Et\ were evaluated in two ways. Firstly, we developed semi-empirical models of post-fire\ Et\ following moderate and high severity wildfire. These models were based on datasets of plot-scale\ Et, measured within five years post-fire, and published literature on post-fire changes in vegetation structure. Secondly, we analysed long-term\ Qrecords (25\ years) from a mixed species catchment, including a 1{\textendash}5\ year period following a predominately moderate severity wildfire. We found that the overall length of recovery time for\ Et\ and\ Q\ following wildfire was 8{\textendash}12\ years, which is much less than for eucalypt forests recovering via seedlings only. This emphasises the importance of functional responses to fire in forest ecosystems as a key driver of the hydrologic resilience of catchments, with resprouting forest types conferring relatively rapid recovery following disturbance. We also found that the recovery trajectory of post-fire\ Et\ was dependent on fire severity. Increased\ Et\ and consequent declines in\ Q\ occurred following moderate severity fire. In contrast, there was no evidence of increased\ Et\ following high severity fire. Based on patterns of long-term\ Q\ and rainfall observed in a small mixed species catchment, declines in\ Q\ due to increased\ Et\ following moderate severity wildfire were of similar magnitude to\ Q\ declines driven by a drought that coincided with the fire. We conclude that the coincidence of wildfire with drought exacerbates reductions in\ Q\ under moderate severity fire, resulting in greater\ Q\ declines. This is due to the enhanced rates of\ Et, primarily driven by regenerating seedlings and higher rates of transpiration from surviving trees.

}, keywords = {Water balance; Streamflow elasticity; Resilience; Disturbance; Fire severity}, doi = {doi:10.1016/j.jhydrol.2015.02.045}, url = {http://www.sciencedirect.com/science/article/pii/S0022169415001572}, author = {Rachael Nolan and Lane, Patrick N. J. and Richard G. Benyon and Ross Bradstock and Patrick J. Mitchell} } @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.} }