Principal component analysis of the annual regime of hydrological and meteorological fields in a river basin

This paper presents a comprehensive consideration of the annual pattern of monthly discharge, precipitation, and water balance in the Kupa river basin (Yugoslavia). For this purpose principal component analysis (PCA) was applied. The monthly discharge values for 25 streamflow measurement stations and the corresponding precipitation and water balance data for 18 weather stations, for the period 1961–1980, were used. For each of the considered fields, two principal components (PCs) are the most significant, and describe more than 85 per cent of total field variance. A significant correlation between discharge PCs and precipitation and water balance PCs was established, especially in the winter season. Thus an explanation of the annual pattern of the discharge in terms of precipitation and water balance has been achieved.