Delimitation and analysis of homogeneous rainfall regions in the south-eastern Transvaal

M.Sc. (Geography)The 1982/1983 drought in the summer rainfall regions of South Africa highlighted the dependence of the agricultural sector as well as the general economy of the country on climatic vagaries. The results as indicated in this dissertation fonn a basis for the development of a yield prediction model for maize in the south-eastern Transvaal. The study consists of two parts, namely:- a) The delimitation of the south-eastern Transvaal into smaller homogeneous rainfall regions. b) An investigation of spatial and temporal rainfall patterns within each region and over the study area as a whole. a) The delimitation of the south-eastern Transvaal into smaller homogeneous rainfall regions: Various methods were investigated for this purpose and T-mode Principal Components Analysis with the subsequent clustering of component scores were found to be the most acceptable. b) An investigation of spatial and temporal rainfall patterns within each region and over the study area as a whole: Various parameters such as rainfall amount~ number of rain-days~ rainfall intensity~ seasonality and variability of rainfall were analysed. The presence of rainfall cycles and absence of linear trends were established. The orographic effect of the Eastern Escarpment on the spatial distribution of rainfall amount, frequency and intensity is clearly shown. Areas where conditions are less suitable for the dry-land cultivation of crops due to factors such as rainfall variability (in excess of 30%), steep slopes and relatively low rainfall intensity, were identified. Significant correlations were found between spring and late summer rainfall of a dry yea