Vanishing beaches: Perception or reality

Abstract

The beach is vital to Australia’s economy and cultural life. As a natural system, the beach can vary in width due to a range of natural and man-made influences. An understanding of the causes of beach erosion is essential. In particular, an assessment of the likely future in terms of coastline stability will require an understanding of what constitutes a major storm or a healthy beach, and what level of variability can we expect in coastal processes. Without this understanding it is difficult to put the postulated long-term changes due to climate change and sea level into perspective. On the world scene beach erosion has become a major issue for community debate and concern. However, many in the community have a perception that the beach should or does remain constant. Others, are aware of variability, but have not been exposed to the extremes of variability. The management of our beaches is clearly an issue in which the community at large has a vested interest. The perception of what beach erosion is within the community is an important factor in the development of effective management strategies. This lecture deals with the current state of the beach worldwide, with particular reference to historical and current beach erosion problems in the South East Queensland – Northern New South Wales region. The various causes of natural variability and man-made influences on beaches are discussed using case studies as examples of how the cause of an erosion problem can be clarified by placing the current condition into a spatial and temporal context over short and medium terms. The causes of erosion have been well documented and can be classified as follows: · Short term natural variability – beach fluctuations, storms · Medium term natural variability – periodic changes in coastal climate and beach conditions · Medium term erosion – disruption to local sediment budget due to man’s activities · Long term natural variability – sea level rise, geological realignment, reduction in sediment supply The latest research into the climatic factors influencing the short, medium and long term prediction of beach erosion will be presented and discussed in terms of local evidence. In the short to medium term, natural and man-made influences can be accommodated with effective management for sustainable development on the beach front. In the long-term, our coastal communities may have to rethink their location and may be forced to consider a retreat from the beach.