PRECIPITATION DISTRIBUTION IN COASTAL BRITISH-COLUMBIA

The spatial distribution and the temporal and spatial variation of the annual, seasonal, and monthly precipitation in two mountainous waters heds in southwestern British Columbia, Canada, have been analyzed usin g a detailed database for 1971-1990 in the Capilano and Seymour waters heds. The analysis showed that the precipitation increases up to the m id-position of the water sheds, and then either levels off or decrease s. Precipitation on mountain slopes and in the valley at the same dist ance from the beginning of the slope is similar, and the barrier heigh t is identified as the dominant parameter which influences the precipi tation distribution. The temporal variation of the precipitation is th e smallest at the mid-position of the watersheds. This variability is the least in the fall and winter and largest in the summer. Correlatio n between the precipitation accumulations at various stations is large , ranging from 0.80 for the wet period of October-March to 0.65 for th e dry period of April-September for distances less than 32 km. Compari son with other studies and the analyses of precipitation and runoff da ta from coastal British Columbia showed that the results of this study are perhaps general and thus transferable to similar areas in the coa stal Pacific Northwest.