Field measurement of soil moisture dynamics and numerical simulation using the kinematic wave approximation

We investigate in this paper the effect of plane and profile curvatures on the soil moisture distribution and related fluxes obtained from field experiments. Today, there is a need also to confirm the theoretical approaches of the kinematic wave approximation with the real field measurements. Within a research project dedicated to the model-based description of runoff formation processes, field measurements of soil moisture dynamics and numerical simulation, using one simply formulated kinematic wave model, are combined. It is shown that the measurement of the soil moisture movement downwards within a hillslope can be interpreted by the kinematic wave model and vice versa how the model can be validated in its physical explanations by the field measurements. It is revealed that the soil moisture fluxes can be described by kinematic waves crossing the soil mantle of the hillslope. Based on these analyses it is shown that the two topographic characteristics plane and profile curvatures of the hillslope control the subsurface and saturation flow. The obtained results are related to the previous theoretical analysis of Fan and Bras [Fan Y, Bras RL. Analytical solutions to hillslope subsurface storm flow and saturation overland flow. Water Resour Res 1998;34(4):921-7], Troch et al. [Troch PA, Paniconi C, van Loon EE, Bijkerk B, Hilberts A. Behaviour of a hillslope-storage Boussinesq model for subsurface storm flow and saturation overland flow. International Workshop on Catchment, Wageningen 2000; Poster] and Troch et al. [Troch PA, van Loon C, Hilberts A. Analytical solutions to a hillslope-storage kinematic wave equation for subsurface flow. Adv Water Resour 2002;25:637-49] which have shown considerable progress in the modelling using the kinematic wave approximation.