Rainfall threshold for hillslope outflow: an emergent property of flow pathway connectivity

P. Lehmann, C. Hinz, G. McGrath, H.-J. Tromp-van Meerveld, J. J. McDonnell
2006 Hydrology and Earth System Sciences Discussions  
Nonlinear relations between rain input and hillslope outflow are common observations in hillslope hydrology field studies. In this paper we use percolation theory to model the threshold relationship between rainfall amount and outflow and show that this nonlinear relationship arises from simple linear processes at the smaller scale. When the rainfall 10 hillslope at the Panola Mountain Research Watershed. Analyzing the measured rainstorm events and the subsurface stormflow with percolation
more » ... th percolation theory, we could determine the effect of bedrock permeability, spatial distribution of soil properties and initial water content within the hillslope. Our results indicate that the measured variation in the relationship between rainstorm amount and subsurface flow is dominated by the initial 15 moisture deficit, the loss of free water to the bedrock, the limited size of the system and by the connectivity due to macropores. The values of the model parameters were in agreement with measured values of soil depth distribution and water saturation.
doi:10.5194/hessd-3-2923-2006 fatcat:z2fedadrijg23pyvsocdc7vksq