Observations on daily rainfall events in the KwaZulu-Natal Drakensberg

Abstract

Five-minute rainfall data measured at different stations in the KwaZulu-Natal Drakensberg are presented and although the data are limited this paper is the first to analyse individual rainfall events in the area. The occurrence of rain days in the Drakensberg shows strong seasonality with most rain recorded during the summer months. Although the number of rain days as well as the number of rainfall events increases with an increase in altitude, the mean daily rainfall and mean rainfall generated from individual events is less on the escarpment than in the foothills. All stations show a high percentage of rain days with single rainfall events as well as a high proportion of rainfall received from events generating more than 10 mm, but the escarpment station receives less rainfall from these events than the stations in the foothills. It is known that rainfall in the Drakensberg is mostly generated from thunderstorms, and data presented here indicate that rainfall predominately occurs in the late afternoon/early evening when sufficient cooling has possibly taken place for condensation and cloud formation to occur.

Keywords: daily rainfall, rainfall events, rain days, Drakensberg