  The surface soil moisture is a key variable to describe the exchange of water
and energy between the land and the atmosphere. In hydrology, and meteorology,
the amount of water in the upper soil layers permits (0-5 cm from the surface)
the evaluation of the relationship between the real evaporation and the
potential evaporation of the bare soil. It is also possible to determine the
distribution of rainfall or other variables such as hydraulic conductivity.
Studies have shown that microwave sensors could be used to scan the surface
soil moisture. The solution choose by the team associated with the SMOS mission
(Soil Moisture and Ocean Salinity) is to use a radiometer (1.4 GHz) to identify
soil microwave emissions . The measurements are made on the site of CESBIO in
Toulouse where a 1.4 GHz radiometer is installed . The effect of vegetation
cover, soil temperatures, snow cover, topography or moisture variations have an
important role in the broadcast microwave surface. Other parameters such as the
presence of inclusions in the ground (holes, stones), or soil texture can also
disrupt measurements. The aim of the work that we present in this paper is to
develop a numerical model to simulate complex geological structures. This model
must take into account all parameters that can affect the equivalent
permittivity measured by the radiometer (surface, moisture variation ,...
inclusions). The purpose of this model is to calculate the equivalent
permittivity of these geological structures in order to be able to associate
with each radiometer measurement an equivalent moisture.
