The wave climate on the KwaZulu-Natal coast of South Africa

The east coast of South Africa has been the subject of numerous coastal developments over recent years. The design of such developments requires a thorough analysis of the local wave climate. Richards Bay and Durban's Waverider data are two relatively long east coast data sets (18 years). These data sets have not been formally reviewed since Rossouw (1984) analysed existing wave data for South African and Namibian coastal waters. This paper aims to provide a formal analysis of the KwaZulu-Natal wave data. Seasonal exceedance probability plots, wave roses and typical wave parameter statistics are presented. Return periods for extreme waves are estimated from the generalised extreme value distribution, and the associated limitations are discussed. The average peak period on the east coast of South Africa is 10.0 seconds, the average significant wave height is 1.65 m and the average wave direction is 130 degrees. Autumn has the most frequent and the largest wave events while summer is the only season unlikely to produce either large or frequent events. The recurrence interval of the largest recorded significant wave height (8.5 m) was estimated to be between 32 and 61 year.