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Global climate change predictions suggest that a rise in sea level, changes in sea temperatures, an increase in the occurrence and intensity of storm events and storm tracks, and altered precipitation patterns could have a significant impact on coastal areas. |
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Considering the value and strategic importance of the coastline, policy and decision makers need to gain a better understanding of the risks posed by a change in marine climate and coastal dynamics.
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The high number of storm events experienced along the KwaZulu-Natal coastline since 2005 have caused coastal erosion and flooding along long stretches of the coastline, with some areas experiencing more erosion than others. Determining which parts of the coast is more vulnerable than others and why, will aid in mitigating the impact of recurrent events (Picture courtesy of Simon Bundy)
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Sundays River Estuary in the Eastern Cape. Estuaries can be restored to a well-functioning, productive state. Maintaining and restoring the health of estuarine ecosystems will support resilience and adaptation to climate change (Picture courtesy of Nelson Mandela Metropolitan University)
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The coastal zone of South Africa, one of the maps available on the coasts and oceans theme page. View larger version
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Pierre de Wet, Andre Theron and Hardus Diedericks, CSIR Natural Resources and the Environment
The relationship between man and the sea dates back to time immemorial.
Considering the benefits derived from this -- oft regarded as boundless -- resource, it is not surprising that a large percentage of human settlement is concentrated in coastal cities and coastal urban areas. In a more modern context, the coast not only provides economic opportunities, derived from operational ports and harbours, but also offers social benefits, such as recreational and amenity areas, housing and development opportunities, and food from fisheries.
Global climate change predictions, however, suggest that a rise in sea level, changes in sea temperatures, an increase in the occurrence and intensity of storm events and storm tracks, and altered precipitation patterns could have a significant impact on coastal areas, among others. Possessing an extensive coastline with a total length of approximately 2800 km, South Africa's coastal resources are vulnerable to these anticipated changes. In particular, coastal settlements are becoming increasingly vulnerable as they are densely populated and subject to rapid growth.
The purpose of the Coasts and Oceans theme page is thus to provide SARVA users with both current and historical data on the South African coastal and marine areas. Due to its nature, the theme is broad in scope and will strive to encompass, inter alia, physical and biological oceanographic data, data on estuaries, legislative issues and relevant international and national documents and articles.
Considering the value and strategic importance of the coastline, policy and decision makers need to gain a better understanding of the risks posed by a change in marine climate and coastal dynamics. The associated potential impacts on existing coastal systems, property and infrastructure also need to be better understood and guidance provided on future coastal developments. By identifying risk factors along the coast and related vulnerable areas, both short and long-term mitigation/ adaptation measures can be developed and informed decisions made with regard to future planning.
The high number of storm events experienced along the KwaZulu-Natal coastline since 2005 serves as an example -- although these storms caused coastal erosion and flooding along long stretches of the coastline, some areas experiencing more erosion than others. Determining which parts of the coast are more vulnerable than others (under present conditions) and why, will aid in mitigating the impact of recurrent events. In addition, estimating how areas that are already vulnerable will be affected in the future due to the effects of climate change is also of importance.
Development too close to the sea has been the main cause of damages to coastal infrastructure and is regarded as a significant future risk. Increased knowledge of the influence of a changing climate on coastal areas will aid the design and identification of safe locations for new developments and infrastructure. It will also assist in identifying adaptation/ mitigation options for developments currently at risk. Where they exist, present coastal development setback lines will have to be revisited and adapted; elsewhere they will need to be determined for realistic, safe future scenarios.
Estuaries form a crucial interface between terrestrial and marine environments and are valuable national assets since they provide essential ecosystem services. Examples of such services are the nursery functions to coastal fisheries, freshwater flows to the marine environment, replenishment of coastal habitats, protection from floods and carbon sequestration.
The National Biodiversity Assessment (NBA) 2011 was led by the South African Biodiversity Institute (SANBI) in partnership with a range of other organisations. The primary purpose of this regular assessment is to provide a high-level summary of the state of South Africa's biodiversity. Special focus is given to spatial assessment.
The estuarine component of this study thus set out to spatially map the physical features noticeable (or that may be inferred) from maps, aerial photographs and satellite imagery for all the estuaries in South Africa. The findings from this study intend to inform decision-makers both inside and outside the biodiversity sector. It feeds into and links with other policy-related processes such as state of environment reports, identification of threatened ecosystems for listing in terms of the Biodiversity Act, the National Protected Area Expansion Strategy, and the National Biodiversity Strategy and Action Plan.
Some of the key findings of this report underline the pressing need for immediate action. For example, currently 61% of South Africa's estuarine ecosystem types have no level of protection, while more than 80% of South Africa's estuarine area is regarded as threatened. St. Lucia, which represents over half of the estuarine area of the country, is in a very poor condition. Overall, estuaries have lost about 20% of their natural freshwater inflow due in large part to an almost 40% reduction (from pristine condition) in the total inflow of the 20 largest catchments in SA.
The pressures exerted on estuarine systems due to the cumulative effect of flow reduction, modification in habitat, fishing pressures and pollution urgently demand management intervention. Additional emerging pressures that may pose a significant risk to biodiversity loss, and will also require consideration, are the presence of invasive alien species, mariculture activities and the construction of desalination plants. Add the anticipated effects of a change in climate to the mix -- such as a potential changes to the salinity profiles, mouth states and river inflows -- and a lack of timely action may have serious ecological, resource and social implications.
The estuary component of NBA 2011 highlights the effects of anthropogenic pressures exerted on estuarine ecosystems. The report interestingly notes that, unlike many other ecosystems, estuaries can be restored to a well-functioning, productive state. Furthermore, while a range of alien invasive fauna and flora species are present in South African estuaries, they do not currently represent a significant threat.
Rapid and decided action is required to ensure this remains the case and to prevent future introduction and spread of invasive species in estuaries. Maintaining and restoring the health of estuarine ecosystems will support resilience and adaptation to climate change.
Visit the Coasts and Oceans theme page for more information.
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