Investigation of regional trends and seasonal shifts in the river flow regimes of Southern Africa

Abstract

The historical trend and variability of river is investigated in 502 river flow gauging in 9 countries of the Southern African region with a view to document the special variability of the river flow regimes. The study identifies regions with strong evidence of declining or increasing trend in annual runoff and those with strong backward or forward seasonal movement in the monthly river runoff across Southern Africa. Of the 502 rivers considered decline in annual runoff has occurred in 250 rivers that constitute 57% of the area considered. Backward seasonal movements have occurred in 180 rivers (42% area studied). The seasonal movement seems to explain the background decline in the trend of the annual discharge of most of the rivers. The decline in runoff is clustered in parts of Zambia, Namibia, Mozambique and the Veld in South Africa.


(Botswana Journal of Technology: 2002 11(1): 57-63)