COASTAL ENGINEERING STUDIES FOR INSHORE MINING OF DIAMONDS AT ORANJEMUND

J.P. Moller, K.C. Owen, D.H. Swart

Abstract


This paper describes a diamond mining operation on the west coast of Africa in Namibia (South West Africa, see Figures 1a and 1b), where a sea-wall of normal beach sand has been built out to a distance of more than 300 m seawards of the original coastline. The wall which runs alongshore is maintained in the high energy environment, which is characterized by northbound longshore transport rates, by means of artificial suppletion at a rate of up to and more than 300 000 m / month. Before embarking on the project the company had to be assured of the sand on the sand-wall; to allow completion of the project free of severe damage by wave action. This implied being able to predict the erosion rate of the sea-wall by the waves. The data set used consisted of wave measurements by Waverider and wave observations obtained from voluntary observing ships; aerial photographs at monthly intervals of the waterline in the study area; and soundings of the beach, sea-wall and nearshore topography by using a helicopter as a platform. Various methods of prediction and projection were used to quantify sediment movement.

Keywords


Oranjemund; diamond mining

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