Is aridity a high-order control on the hydro-geomorphic response of burned landscapes?

Fire can result in hydro-geomorphic changes that are spatially variable and difficult to predict. In this research note we compile 294 infiltration measurements and 10 other soil, catchment runoff and erosion datasets from the eastern Victorian uplands in south-eastern Australia and argue that higher aridity (a function of the long-term mean precipitation and net radiation) is associated with lower post-fire infiltration capacities, increasing the chance of surface runoff and strongly increasing the chance of debris flows. Post-fire debris flows were only observed in the more arid locations within the Victorian uplands, and resulted in erosion rates more than two orders of magnitude greater than non-debris flow processes. We therefore argue that aridity is a high-order control on the magnitude of post-wildfire hydro-geomorphic processes. Aridity is a landscape-scale parameter that is mappable at a high resolution and therefore is a useful predictor of the spatial variability of the magnitude of post-fire hydro-geomorphic responses.