This book is about deriving areas within the Save catchment of Zimbabwe that are of equal hydrology, meaning the areas within this catchment that have similar flow charateristics. The main argument in the book are that most of the sub catchments in the area are ungauged yet flow characteristics of the rivers in the area essential for planning purposes for things like allocation or licensing of abstractions and storage of water, the development of in stream or environmental flow requirements of water, yield analysis of proposed reservoirs, for providing an estimate of the potential renewable water resource of the entire catchment. This creates the need to develop methods for estimating runoff on ungauged catchment. Flow characteristics of a river are a function of the catchment characteristics and research determined the catchment charateristics that significantly affect runoff through the use of a technique called redundancy analysis. These were then used to group the sub zones into units that are similar in character. This was done through the use of cluster analysis. Homogeneous Hyrological regions for the Save Catchment were then determined and their validity was tested.