Soil moisture is a fundamental state variable for understanding hydrological processes in the vadose zone and the storage-discharge relationship of a catchment. However, soil moisture is highly variable in space, and that complicates the estimation of soil moisture values that could be representative of the whole catchment system. The Cosmic Ray Sensor (CRS) is a new promising technique that detects soil moisture over wide areas, covering up to 30 hectares, and it’s currently subject of research. In this thesis, the data detected by a CRS, installed at the intersection point of three fields, were combined with soil moisture data determined from samples and used to calibrate a Hydrus-1D model.