Observations of the oceanic environment and warm-water outfall near the Koeberg Nuclear Power Station, South Africa

Abstract

The oceanographic dynamics of a small-scale coastal upwelling site near the Koeberg Nuclear Power Station are investigated by means of spatial observations over a 10-km domain and time-series analysis at scales of hours to months. The background environmental data set used for the siting and engineering design aspects includes analyses of sea temperatures, winds and waves in the nearshore zone. The relationship between winds and coastal upwelling is established and statistical analyses reveal prominent cycles at 24 hours and 5–20 days. The extent, trajectory and dilution of the heated effluent water discharged by Koeberg in its operational mode is studied by means of field observations. Intensive surveys, made under various conditions, show that the warm plume mixes via inherent turbulence and wave action. Wave action and the breakwater structure cause the plume to drift southwards along the beach. Farther offshore, the buoyant plume spreads laterally, halving the sea temperature excess. Outside the surf ...