Search

The 550 km-long KwaZulu-Natal coast broadly divides into a bedrock-framed southern section and northern coastal plain section, each of approximately equal length. Seven types of coastal dune are identified on this coast: estuary barrier dunes; mainland beach foredunes; prograded beachridge dunes; headland bypass dunes; transverse dune fields; parabolic/migrating dunefield; and climbing dunes. The development and distribution of the various dune forms is more strongly controlled by the geological setting, than the aerodynamic regime. [ABSTRACT FROM AUTHOR]

On a generational scale, on developed shorelines, the world's recreational beaches are doomed. This is largely because of the widespread assumption that preservation of buildings is a higher priority than preservation of beaches in response to sea level rise. Continuing beach degradation will be inevitable through active or passive processes. Active degradation means the actual removal of the beach, mostly as a result of shoreline engineering or mining. By far, the most important cause of beach loss in this category will be hard structures, especially seawalls. The incorrectly but widely perceived panacea of each replenishment will become economically impossible because of raised sea levels. Replenishment leads to intensified beachfront development and this ironically and inevitably will increase the future construction of seawalls. Passive degradation refers to reduction of the quality of the beach to the point that human usage drops, along with political support for costly beach preservation by nourishment. Passive degradation includes trash accumulation, oil spills, beach driving and most importantly, pollution, which is increasing rapidly apace with population growth and remains largely unrecognized by the beach-using public. [ABSTRACT FROM AUTHOR]

Cliff-top storm deposits (CTSDs) occur south of Morgan Bay, South Africa at elevations varying from ±55- to 63m. These occur as a ±10m-wide horizontal fringe of shell breccia mixed into a very thin (>15cm) sandy soil on the cliff top platform. Visually it is evident that the shell breccia is of various ages. Comparisons with proven wave breccia from this area indicate the same source. We suggest that this breccia was deposited as fall-out from wave and wind-borne plumes produced by wave bores striking the cliff base. These bores would likely have been produced by waves at least ~40m in height. Alternative interpretations, such as a perched marine desposit or tsunamiite are rejected in favour of CTSDs produced by multiple large wave events. [ABSTRACT FROM AUTHOR]

Coastal storms are highly significant and destructive events and important natural hazards that have major impacts upon the physical and human-cultural coastline environments. Exceptional coastal storms in the last decades have emphasized the urgent need to reinforce scientific knowledge regarding the frequency, impact and role of these extreme events. This is particularly relevant for embayed beaches, where geomorphological control promotes characteristic morphodynamic responses that are distinct from the better studied long-linear beaches. This paper analyses storm response from datasets of morphological change obtained from three embayments located in three distinct wave environments. Analysis of the morphological response to extreme storm events, particularly the 2007 March Equinox storm in eastern South Africa, the January-February 2009 storm group in southwestern Portugal and the December 2011-January 2012 storm group in northwestern Ireland, demonstrate that storm-induced morphological change in the Durban Bight, Arrifana beach and Portstewart Strand is highly variable alongshore. Retreat values for the mean high water spring shoreline are shown to differ significantly within each embayment. This alongshore non-uniform response to storm-events is attributed to boundary effects triggered by the presence of natural headlands or outcrops and/or artificial engineering structures. Megarip development drives variability in storm response in Arrifana, while wave shadowing and interruption of longshore sediment movement under south-easterly/west-northwesterly storm waves promotes the northward/westward increase in shoreline retreat in the Durban Bight and Portstewart Strand, respectively. Boundary effects significantly influence short-term morphodynamic behaviour during storms and, consequently, determine alongshore non-uniform morphologic response to storm events, irrespective of embayment dimensions and event magnitude. [ABSTRACT FROM AUTHOR]