Topography effects on small-scale precipitation variability in the Swiss pre-Alps

Long-term precipitation and snow-cover measurements were carried out to estimate the areal pattern of precipitation in a small, rugged Swiss pre-Alpine basin. The dense networks used consisted of 34 storage gauges and 32 pit gauges with orifice parallel with slope, the latter being corrected for wetting losses. Consequently, the corrected data was very near to the true precipitation at a particular point. In the winter season also snow-cover characteristics were measured at 11 locations. Altitude turned out to be the best overall predictor for corrected data (R 2 = 0.67) and longitude for uncorrected data (R 2 = 0.67 vs only 0.58 for altitude!). The combination of altitude, longitude and latitude explains almost 75% of the spatial variance of summer season precipitation and snow-cover characteristics. However, the three variables used in the analysis were found to be interrelated, particularly in networks of storage gauges and snow-cover measurements (R 2 = 0.40-0.70).