Raingauge network designs for Uganda

Abstract

The effective use of rainfall informations for all water use activities can only be derived from well designed raingauge networks. The objective of this study was to design raingauge networks for Uganda. Two basic concepts were used, namely: the 'minimum, and 'optimum' network principles. Under the minimum network design, the minimum number of raingauges that must be operated in order to represent all the climatological divisions are determined. The optimum network design on the other hand, constitutes the least number of raingauges which must be operated in order to obtain optimum rainfall informations for the various water use activities. Monthly rainfall records at 102 stations spanning within the years 1940-1985 were used in the study. Data quality control tests were used to test the quality of the few missing estimated records and all rainfall records before they were used in the study. Principal component aria Lysi.s (PCA) was used first to delineate Uganda into homogeneous rainfall subdivisions based'on the spatial patterns of the dominant PCA modes. Areal rainfall ~alues are usually better indicators of the synoptic systems controlling rainfall than point values at the individual locations. The areal rainfall estimates derived from the simple arithmetic mean and those obtained from PCA solutions were used to examine the skill of the developed network designs in the representation of the spatial and temporal rainfall characteristics at the PCA derived climatological divisions.