Author(s): Paule Hainz; Gregor Rickert; Gokben Demir; Zhi Li; Daniel Caviedes-Voullieme; Ilhan Ozgen-Xian
Linked Author(s): Ilhan Özgen-Xian
Keywords: Post-fire hydrology; Integrated hydrological modelling; Ecohydrology; Recovery trajectories
Abstract: Wildfire severely disturbs the hydrology of forest ecosystems. The fire burns down vegetation and alters soil structure, leading to reduced infiltration and increased overland flow. These changes in hydrology often give rise to water-related hazards such as flash floods, droughts, and debris flow. Over time, the system recovers from the fire, the soil and vegetation regenerate, and hydrological signatures (runoff, soil moisture, percolation, and evapotranspiration) return to their pre-disturbance values. This contribution presents exploratory numerical experiments on idealised hillslopes in temperate forests that explore the sensitivity of the recovery time to recovery trajectories of soil and vegetation. The simulations were run using the physics-based ecohydrological model SERGHEI, which solves integrated surface–subsurface flow with the shallow water equations and the Richards(on) equation, respectively. Potential evapotranspiration is computed externally using the Priestley–Taylor equation and imposed on the system as a time series. Simulations start from the same initial conditions of bare burned soil that regenerates its hydraulic properties over time and completely burned vegetation that grows back over time. Soil hydraulic properties alter the van Genuchten–Mualem soil constitutive model that predicts effective parameters for the Richards(on) equation solver. Vegetation recovery informs parameters of the Priestley–Taylor equation and root water uptake. We define different sigmoidal, U-shaped, and cyclical trajectories for both the soil and the vegetation. The system is considered as hydrologically recovered, when 80% of the pre-disturbance evapotranspiration rate is recovered. Our results will allow us to identify, for different combinations of recovery trajectories, (i) critical recovery thresholds for post-fire hydrology, (ii) hierarchy of controls on post-fire hydrology, and (iii) relation between recovery time and recovery trajectories.
Year: 2026