UNDERSTANDING THE PHYSICAL STRUCTURE OF SOUTHERN AFRICA'S STANDING WATERS

SUMMARY

An examination of the nature of the stratification in polymictic and monomictic Southern African reservoirs is presented. Wind stirring is the principal mode of heat transfer during spring heating. In high summer radiation from stable heated surface layers is responsible for the generation of turbulent kinetic energy (TKE) as a consequence of cascading of high density water downwards to neutral density levels. Entrainment of warm layers by inflow gradients in the reservoirs of the summer rainfall regions of the subcontinent is a further important mechanism setting up TKE in the epilimnion. It may become dominant during periods of high river inflow and often precedes autumnal turnover.

KEYWORDS:

• Mixing layer dynamics
• inflow gradients
• turbulent kinetic energy