Probabilistic modelling of water balance at a point: the role of climate, soil and vegetation

The soil moisture dynamics under seasonally fixed conditions are studied at a point. The water balance is described through the representation of rain fall as a marked Poisson process, which in turn produces an infiltration in to the soil dependent on the existing level of soil moisture. The losses fr om the soil are due to evapotranspiration and leakage, which are also consi dered dependent on the existing soil moisture. The steady-state probability distributions for soil moisture are then analytically obtained. The analys is of the distribution allows for the assessment of the role of climate, so il and vegetation on soil moisture dynamics. Further hydrologic insight is obtained by studying the various components of an average water balance. Th e realistic representation of the processes acting at a site and the analyt ical tractability of the model make it well suited for further analyses tha t consider the spatial aspect of soil moisture dynamics.