Basin characteristics are central to the regionalization of hydrological parameters and, in particular, runoff. Two examples are provided which demonstrate that Geographical Information Systems (GIS) can supply such characteristics at a national level, assuming that the necessary base data are available. These methods offer great potential for coordination and open new horizons for regional hydrology. The experience gained by the Swiss National Hydrological and Geological Survey is used to demonstrate the advantages which accrue from the flexibility of the application of GIS at regional and national levels.