Modelling the Agulhas Ocean Current: With A Focus On The Related Shallow Water Hydrodynamics In And Around The Durban Bay, South Africa

Coastal currents can be significantly influenced by boundary ocean currents when these ocean currents travel along the edge of a continental shelf and when this shelf is narrow. These ocean currents are a result of large-scale temperature and salinity differences and eddies or gyres can form from them. I was chosen for an internship at Deltares in Delft, Netherlands, to help develop and study the use of Delft’s Flexible Mesh FLOW model.

With this study, I aim to use the Delft 3D-FLOW Flexible Mesh to model and analyse the Agulhas Current and its effects on the Durban coastline. The need for an accurate hydrodynamic model that represents the Agulhas Current and its related on-shelf circulations, in addition to tidal- and wind-induced currents, is essential to studying currents off the Durban and KZN coastline. Global ocean models, such as the model operated by E.U. Copernicus Marine Service Information (CMEMS), include the Agulhas Current, but are not suitable for coastal applications due to their relatively coarse resolution. For this reason, I down-scaled the Agulhas Current from the CMEMS ocean model to a local scale Delft3D-FLOW Flexible Mesh model of KZN, by applying appropriate boundary conditions and a new nudging technique. My thesis will outlay the processes and tools that I will utilize to set-up and achieve a stable, 3D-model that can successfully replicate the Agulhas Current alongside the KwaZulu-Natal coastline.

With my research model, I hope to achieve realistic currents that will develop along the relatively shallow Durban and KZN coast. I will then verify this model and compare results to ADCP data from the ACEP project collected by SAEON. 

Figure 1: Comparison between my model results (left ) and CMEMS (right)

Kemira Naidoo

BSc Eng (Civil)

MSc ENG (Civil)