Management implications of development resulting in disruption of a headland bypass dunefield and its associated river, Cape St Francis, South Africa

Abstract

Historically the functioning of headland bypass dunefields has been poorly understood. This has resulted in their inappropriate stabilisation and development since the late 19th century. The best remaining example of an active headland bypass dunefield on the south coast of South Africa is the 17 km long Oyster Bay-St Francis Bay dunefield. The eastern, downwind section of the dunefield is drained by the Sand River. Prior to 1960 the eastern end of this dunefield was largely undeveloped. Since 1960 poorly planned developments have disrupted the natural functioning of both the dunefield and the Sand River. The channel of the Sand River has been artificially diverted and during peak rainfall periods certain developed areas are now under threat of flooding. Construction of a road across the dunefield and Sand River restricts the natural water and sediment flow. The Sand River has also been identified as a major potential contributor to the sanding up of the Kromme River, a popular recreational area. Future developments in the coastal zone should take place with due cognisance of the role of local sediment transport systems. With increasing demand for recreational usage of the coastal zone, coastal managers need to prevent the costly recurrence of poorly planned development. Coastal sediment transport systems need to be managed as a whole.