Rainfall and flow variations in the Lesotho Highlands

Abstract

The Lesotho Highlands contain some of the highest mountains in southern Africa and play an important role in the surface water resources of the region. Several features of the climatology and hydrology of the highlands are reviewed here. The emphasis is on the long-term response and the behaviour on an annual basis. Topics discussed include the variations in rainfall with elevation and location, the relationships between annual rainfall and river flows, and the variations over time in both rainfall and flow records. Results are presented in the form of updated versions of the mean annual precipitation and mean runoff coefficient maps for the region, and examples are presented for typical regression relationships between flows and rainfall data on an annual basis. Also, statistical analyses are described that suggest little evidence for any significant cyclical behaviour or trend during the observational periods for either rainfall or flow data. © 1998 Royal Meteorological Society