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The Determination of Cope Levels in Modern Ports: A Case Study for the Port of Ngqura, Coega River Development

The Port of Ngqura is the newest deep-water port in South Africa, and is located 20 km to the east of the Port of Port Elizabeth. The main business of the port is handling containers for transhipment, with a new container terminal up the Coega River planned as a future port expansion. Port planning is predominantly concerned with the development of infrastructures in a dynamic marine environment dictated by tides, waves and coastal sediments, including long-term sustainability impacts such as rising sea levels and configuration / size of new generation vessels.

The determination of quay wall elevations (cope levels) is critical in a port as it affects the way cargo is handled and protected against flooding from the sea. The future cope level for the Port of Ngqura Coega River expansion, taking into account future impacts of global warming, future site conditions and new shipping technologies, has not yet been determined.

This prompts the question: “What is the most suitable future cope level for the Port of Ngqura Coega River terminal?’ This study addresses the above research question, by conducting a detailed review of industry practices, methodologies and parameters required in the determination of cope levels. Included in the assessment was a detailed review into specific parameters such as global warming impacts, modifications to the Coega River and its flooding impact on the port, and the operational related requirements of new generation container vessels on modern ports.

A brief overview of the existing cope levels at the eights South African commercial ports (Saldanha, Cape Town, Mossel Bay, Port Elizabeth, Ngqura, East London, Durban and Richards Bay) was also done. From the review of current industry practice and cope level determination methodologies, basic principles were used in the determination of the cope level for this study, which required the identification of extreme water levels such as the Design Still Water Level (DSWL) (astronomical tides, storm surge, long waves and sea level rise) and the Design Water Level (DWL) (wave effect on top of the DSWL). Existing metocean datasets for the Port of Ngqura was used and new data required for this study was produced from this same set.

The study has established that climate change is a big factor that needs to be considered when designing cope levels for the future. The expected climate change impacts include: sea level rise, increased rainfall in the Coega area and increased wave heights due to increase in wind speeds. All of these have the potential to flood the port. The impacts from new generational vessels and from flooding of the Coega River were found to be negligible in the determination of the required cope level, however they presented other impacts to port operations that justified the need for other studies to be conducted but not covered under the scope of this study. Based on this study, it is recommended that focus is placed on understanding the current and future climate change impacts on ports, taking into account the risk appetite of the respective port authority. For the Port of Ngqura Coega River Terminal Expansion, based on a 1 in 1 000-year return period and extreme events over a 100-year design life, a final future cope level of +7.5 m Port Chart Datum is recommended.

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