Using a Complementary Evapotranspiration Relationship to Estimate Surface Suction for Soil-Atmosphere Interaction Analysis

The estimation of soil surface condition from climatic parameters is of great importance in soil-atmosphere analysis. This paper deals with the estimation of the surface suction of soils using meteorological data. The rate of evapotranspiration (AE/PE) is related to the soil surface suction by the Wilson equation and it is generally used when the potential evapotranspiration (PE) and the soil surface suction are known while hydrological models allow the calculation of the evapotranspiration rate (AE/PE) by introducing complementary relationships. In this paper, a complementary hydrological model was combined with the Wilson equation in order to estimate the soil surface suction in time. To test the validity of the results, the approach was applied to the Toulouse region in the south of France in 3 different years (1999, 2003, 2004). The 2003 year was distinguished as a high intensity drought period in France that has caused many damages by triggering shrinkage and swelling in clays. By comparing the estimated total surface suction for these three years, the 2003 year showed higher values compared to the two other years as expected.