Andrew A. Mather

Southern African sea levels: corrections, influences and trends

The tidal records of existing South African and Namibian tide gauges are examined and corrected. Regional sea level trends vary, with the West Coast rising by +1.87 mm y−1 (1959-2006), the southern coast by +1.48 mm y−1 (1957-2006) and the East Coast by +2.74 mm y−1 (1967-2006). The effects of barometric pressure and vertical crustal movement changes on these trends are examined. The derived relationship between sea levels and barometric pressure changes varied between 5.71 and 7.67 mm hPa−1, significantly less than the theoretical inverse barometric correction. Barometric pressure has been dropping along the west coast at 1.63 hPa per decade (1987-2006), has remained fairly static along the southern coast and is rising at 0.30 hPa per decade (1970-2007) along the east coast of southern Africa. The West Coast barometrically corrected sea level trends show that most of the change can be attributed to falling barometric pressure, whereas along the East Coast, the barometric pressure increase is suppressing sea level by 0.2 mm y−1. Vertical crust movements vary, with the largest recorded movements of +1.11 ± 0.25 mm y−1 found along the East Coast. Movement rate reduces southwards. Eustatic sea level trends vary from +3.55 mm y−1 along the East Coast and +1.57 mm y−1 along the southern coast to +0.42 mm y−1 along the West Coast.

Adaptation in Practise: Durban, South Africa

This paper outlines the development of the first municipal adaptation plans for climate change in Durban, South Africa. Particular attention is paid to the storm water and coastal plans developed for the water sector. Key adaptation activities in the main operational departments are highlighted as well as the key challenges and lessons learned during the development of the plans. Three factors were significant in determining the success of the project: (1) the emergence of political and technical champions, (2) the existence of high level technical expertise within the municipality and (3) broad based and appropriate communication with stakeholders.

Failed Coastal Stabilization: Examples from the KwaZulu-Natal Coast, South Africa

Coastal stabilization, mostly involving coastal dune cordon destruction, has been practised on the KwaZulu-Natal coast for the last two decades. During this time no major swells occurred. The last Lunar Nodal Cycle (LNC) tidal peak was associated with a series of unusually high swells. The temporal coincidence of exceptionally high tide and large swell led to catastrophic coastal erosion and underlined the folly of coastal stabilization, especially at reversing erosion hotspots, many of which are urbanized and defended. These locations remain at risk and will experience future erosion.

Communicating Flooding Issues to the Public at Large

The coastal area of KwaZuluNatal is subject to regular flooding, ranging from severe regional flood events such as the 1987 floods when 300 people lost their l…