Prof Robert Nicholls reports:
Dr. David Harlow (Coast Protection Manager, Bournemouth Borough Council) presented the nearly 50 year history of the Bournemouth Beach Nourishment Project on Tuesday 20 February 2018. His talk, entitled “Bournemouth Beach Replenishment, 1970 to 2016” looked at the history of Bournemouth as a tourist resort in the early 19th Century to today, and how erosion has probably been a feature of that coast for millennia. Armouring of the coast over the last 100 years removed the source of beach sand and ultimately triggered the need for management using beach nourishment as we see today. A total of over five million cubic metres of sand has been added to Bournemouth beaches in that period. He explained how nourishment has become more efficient with time and how it has moved from being reactive to erosion to being more planned and anticipatory of future erosion.
Groynes are key to minimising the loss of the beach material and the talk included the lessons learnt on groyne construction. In Bournemouth, timber groynes are still the norm and experience with factors such as spacing, height and shape were all considered. The limited tidal range is a severe constraint on groyne construction and cost. Emerging problems of wind-blown sand were also mentioned due to the widened beach, something that requires continuous cleaning of the promenade which is a national cycle route. Managing the beach requires collection of regular beach profiles across the dry beach and down to depth of closure, as well as grain size samples. In fact, the beach profile data at Bournemouth is the longest continuous dataset in England. The grain size data showed the surprising result that the beach was getting finer, a trend which they are planning to reverse by placing coarser sand in the future.
It was clear that a long-term strategic and science-based plan for Bournemouth’s beaches has been developed and will be implemented over the coming decades. This includes consideration of sea-level rise. David also explained he would retiring shortly and handing over the reigns for these future interesting developments. The audience showed their great appreciation for this excellent overview of decades of experience and wished a David a happy retirement. The talk is available via this link.