This report presents the results from the project called " Utilisation of weather radar data in atmospheric and hydrological models" funded by NFR and Energy Norway. The classical formulation of the regularization of a random variable allied to a simple model of rain field advection allowed us to propose a coherence framework to fit a set of experimental rainfall variograms at different time steps using a unique theoretical space-time variogram. This elemental variogram is supposed to describe the rainfall variability at unobserved small scales. The number of parameters needed by the framework is limited, namely the space and time range of the elemental variogram, its sill and the advection velocity of the rain fields. The identification of these parameters through a simple optimization tool appears to work well in the case of a very elementary hourly rainfall database. The quality of fit of the experimental variogram is fairly good up to 3-hour durations, and the identified parameters look physically sound, providing typical velocities, sizes and lifetimes. This space-time model will be used as a basis for providing precipitation products based on radar and rain gauge measurements.