Consequences of Sediment Discharge from Dune Mining at Elizabeth Bay, Namibia

Abstract

Nearshore turbidity owing to suspended fines is a natural phenomenon around much of the western coast of southern Africa. However, the potential impacts of diamond-mine-related sediment tailings on local biotic communities at Elizabeth Bay in Namibia have been the subject of comprehensive ongoing assessment. This paper discusses field measurements and mathematical modelling carried out to quantify the extent and relative influence of sedimentation and turbid plumes associated with the mining operation. Following validation of the various mathematical models using available field measurements, the models are used to predict shoreline evolution and nearshore turbidity response for various scenarios, including the situation towards the end of mining operations. The principal finding is that, although the mine discharge causes significant shoreline accretion and elevated turbidities in the nearshore regions of the bay, turbidity levels in the region of concern beyond the confines of the bay will remain below critical threshold levels for impacting on local biota.