Using 45 rain gauges, located in the center of French-speaking Switzerland (approx. 1,600 sq. km), we evaluate an annual mean precipitation map for the years 1974, 1975 and 1976. This estimate is based mainly on the anomaly method. For the index elevation, we selected an average altitude over an area of optimized size. This was evaluated from the best linear regression between index elevation of different areas and the precipitations.
An anomaly map was estimated using universal kriging: the structural analysis of the anomaly values permitted the adjustment of a variogram which made it possible to evaluate the spatial dependence of the anomaly variable. In order to obtain the precipitation map, not only was an anomaly map used but also a smoothed altitude map. This was calculated with the aid of an altimetric data bank covering the west part of Switzerland