Natural variability and anthropogenic effects on the morphodynamics of a beachdune system at Montrose Bay, Scotland

Beachdune systems are valuable geomorphic assets providing a buffer between the coastal hinterland and the sea. Sustained coastal erosion can diminish the protective capability of the beachdune system with potentially negative implications for coastal amenities, infrastructure, ecology, and archaeology. To develop suitable management solutions in response to erosion, it is necessary to ascertain spatiotemporal variations in the processes that affect site-specific coastal morphology. This study examines a beachdune system at Montrose Bay in eastern Scotland that is undergoing severe erosion, threatening the current layout of the Montrose Medal Golf Course. Sediment eroded from the golf course frontage is deposited at the northern end of the bay where contemporaneous accretion has occurred. Analysis of sediment transport rates, time-series aerial photography, and historical maps indicate that the current spatial distribution of erosion and accretion at Montrose Bay is likely due to a strengthening of northerly drift, driven by waveclimate change during the 1980s. This natural variability was examined further through assessment of earlier changes in coastal morphology apparent in historical mapping and from archaeological evidence of shoreline change reflecting the temporal dynamism of soft sedimentary coasts. The removal of sediment dredged from the South Esk estuary in the closed coastal system is shown to be a major anthropogenic influence on the beachdune system in recent decades based on a simple quantitative analysis of dune erosion due to removal of beach sediments during dredging operations. © 2012, the Coastal Education & Research Foundation (CERF)