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Designing the second nourishment and investigating its future management
Group Members
Giulia Billi, Siân Crotty, Georgina Davies, Matthew MacRorie, Emily Rodda, Anthony Scoones
Professor Robert Nicholls, Dr Joel Smethurst, Dr Alexandra Toimil Silva
Lauren Burt (New Forest District Council)
Hurst Spit, a shingle beach in the New Forest, protects the coastline between Milford-on-Sea and Lymington, sheltering several assets in its lee from large waves originating in the Atlantic Ocean. For centuries, Hurst Spit has been naturally retreating inland, but its recent loss of material has been significant, likely due to hard defences preventing sediment movement along the coast. The damage sustained to Hurst Spit during an extreme storm in February 2014 highlighted the need for its nourishment to enhance storm-resilience by artificially adding beach-grade sediment.

The management of Hurst Spit must be planned for 100 years, in accordance with government policy. Therefore, a nourishment scheme with a lifespan of 20 years has been designed in detail and subsequent management needs investigated in more general terms.

The nourishment proposal is based on the analysis of topographic and hydrographic surveys, and wave and tide data. Nourishment profiles are designed, using novel numerical modelling, to sustain limited damage in an event based on the extreme 2014 storm, so that the nourished spit remains resilient against following storms. Other major design considerations were the variable wave climate along the spit, consolidation of the marsh behind, and the impact of long-term sediment losses. The proposed nourishment scheme requires up to 500,000m3 of sediment over the 20-year design, costing approximately £20.4 million.

Finally, state-of-the-art scenarios were used to explore plausible sea level rise and its impact on Hurst Spit, forming the first step towards developing an adaptive pathway. Overall, it was found there would be no technical barrier to future nourishments up to 2120.