Author(s): R. Van Ballegooyen; S. Taljaard; L. Van Niekerk; P. Huizinga

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Keywords: South Africa; Palmiet Estuary; Kromme Estuary; stratified; partially stratified; 3D numerical modelling; hydrodynamics; salinity; dissolved oxygen

Abstract: A limitation in predictive capability in South Africa is the lack of predictive tools to simulate hydrodynamic and biogeochemical processes in small stratified or partially stratified estuaries. Investigations on the applicability of available three-dimensional (3D) numerical models, in this case Ihe DELFT3D-FLOW model, were undertaken using the Kromme and Palmiet estuaries as case studies. Of particular importance in these small stratified or partially stratified systems is the accurate simulation of the vertical mixing and entrainment processes as these are important determinants of the flushing rates and water quality in these estuaries. In both of the above case studies, the 3D model simulations accurately reproduced the major features of these stratified systems for a month or more, particularly the flushing rates. However, the significant computational effort required for 3D models typically restricts the simulations to monthly (i.e. event scales) or seasonal time scales. This paper concludes that a predictive capability, based on 3D hydrodynamic models, can be implemented for small stratified and partially stratified estuaries. The planned implementation of a similar 3D water quality model will further enhance the capability to predict the consequences of estuarine management strategies in such estuaries.

DOI: https://doi.org/10.1080/00221686.2004.9628311

Year: 2004