The geography and topography effects on the areal pattern of precipitation in a small prealpine basin

Abstract

Analysis of altitudinal dependency of corrected summer season, June-September, precipitation data from 61 gauges shows that precipitation in the valley and on the leeward slopes of a small, rugged prealpine basin, 13 km2 in area, is greater than that on windward slopes. This indicates that (i) the redistribution of precipitation by wind can play a significant role in the spatial distribution of precipitation in mountainous areas, (ii) the use of exclusive valley positioning of gauges which is the common practice in the mountains can overestimate the precipitation on slopes and (iii) the results of studies of effects of geographic and topographic variables on the precipitation in the mountain are biased and rather network specific than physically based, and considerably depend on the general strategy of the network design including the gauge type and positioning of gauge sites. The corrections of wind-induced error were based on comparisons of precipitation from paired ground level gauges and elevated gauges. Such pairs have been situated under different exposure conditions. The corrections included also wetting and evaporation error, and amounted from 5 to 15% depending on the gauge type and site altitude, exposure and insulation.