The elaboration of appropriate SVATs (Soil Vegetation Atmosphere Transfer) models is of great importance for the understanding of the mechanisms of the surface flows transfer, with applications to the atmospheric circulation, hydrological and ecological modeling. In this paper, a SVAT model developed for the Cariri region, Paraíba state, is used to analyze the effect of the high temperature gradients observed in the upper soil layer on the soil moisture dynamics and it is shown how the low thermal diffusivity of the soil of the experiment causes these high temperature gradients which break down the evaporation rate during day time. The sensitivity of the soil evaporation rates to the spatial variability of the heat conductivity at the experimental site is also shown. One concludes that mainly in semi-arid region more attention must be paid to the parameterization of the thermodynamics properties of soil.
SVATs model; heat and mass transfer; thermal diffusivity
