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McCue, J., Pye, K. and Wareing, A. (2010) Beach nourishment operations in Wales and likely future requirements for beach nourishment in an era of sea level rise and climate change - a pilot study. Report to Countryside Council for Wales by Atkins Ltd. and Kenneth Pye Associates Ltd., CCW Science Report No. 928, Countryside Council for Wales, Bangor. Executive Summary Beaches are a key natural, social and economic resource for Wales. They not only provide a vital coastal defence function for local communities, and material for the maintenance of key natural habitats of national and international importance, but they also represent one of Wales’s premier landscape and recreational assets which underpins coastal tourism. The Welsh coast, for example, is vitally important to the tourism industry in Wales. Within the Welsh regions, seaside tourism is particularly important for the North and South West, where it accounts for 52% of tourism spend. The spending associated with an overnight visit to the coast, in 2009, amounted to around £601million or 43% of total tourism spending in Wales. Importantly, visits to the coast account for 37% of all overnight trips in Wales (Welsh Assembly Government, 2010). By contrast the Welsh Assembly Government’s budget for 2009/10 for supporting the work of Welsh local authorities for both inland and coastal defence works was £6 million with the majority being targeted on defending assets to the rear of the defences. A minimal proportion of this budget was used to enhance beaches.
With these important economic statistics in mind, there are some major future challenges to maintaining and enhancing beaches. Sea level rise and climate change represent a potentially serious threat to Welsh beaches, particularly those fronting hard defences. Beaches are often under pressure as a consequence of existing defences because they have removed sediment sources from the system. However, to cope with sea level rise and maintain beaches at the same relative position to the tides they need substantially more sediment which is often not now naturally available.
Linked to the above, one of the key issues Wales is likely to face relates to how much more sediment is likely to be required to restore and maintain healthy beaches, where will it come from and how will it be paid for. To try and address the first of these issues Atkins Ltd together with Kenneth Pye Associates Ltd (KPAL) were commissioned by the Steering Group to carry out a desk based research project to consider the likely requirements for beach nourishment operations over the coming century. To do this a representative sample of ten Welsh beaches was chosen which encompassed the range of the Welsh beach resource.
For each of the ten selected case study areas, estimates have been made of the sediment nourishment volumes that would be required to carry out an initial 'beach improvement' followed by re-nourishment at 5 yearly intervals in the following 20 years, assuming that 50% of the emplaced sediment is lost between re-nourishment events, and allowing for projected sea level rise over the same time period. The best estimate sediment volumes for the UKCP09 medium emissions sea level rise scenario range from 142,000 m3 at Tenby North Beach to 2,017,000 m3 at Aberavon Sands.
The results of the potential sediment nourishment requirements under each of the sea level rise scenarios considered, show that initial beach 'improvement' nourishment volumes at all of the identified sites are relatively modest, the largest being 641 x 10 requirements for the smaller enclosed embayment sites such as Tenby North Beach, Traeth Crugan and Port Eynon Bay are relatively small (< 150 x 103 m3).
The volumes required to maintain the existing beach profiles at the ten sites vary considerably, depending both on the length of shoreline, the tidal range (and therefore beach width), and the rate of sea level rise considered. Considering the 'best estimate' (50th percentile) value for the medium emissions scenario, the smallest volumes of sediment required by 2100 would be at Tenby North Beach and Traeth Crugan (24 and 30 x 103 m3 volumes would be required in Swansea Bay North and at Aberavon Sands (614 and 541 x 103 m3, respectively). None of the values are particularly large when compared with nourishment volumes for large schemes already carried out in England, such as those at Bournemouth, Mablethorpe - Skegness and Heacham. It should, however, be borne in mind that these 'volume increase’ calculations do not take into account sediment losses which would inevitably occur following initial nourishment and each re-nourishment.
The pilot study calculated values for the amount of sand needed are, however, a product of the methodology used and are likely to change if a different methodology was used. Nevertheless, they can be considered indicative of the likely scale required and it is hoped to refine some of these estimates in later work. The results therefore are intended to inform the next phase of work which will be carried out with further funding from the Aggregates Levy Fund for Wales. Consideration of future nourishment at the pilot sites (or other locations where significant volumes are required) needs to consider all resource options and would form an important element of the proposed future study.
In conclusion, the pilot study has highlighted the important benefits that beach nourishment could provide and fully justifies the more detailed consideration of its use. The study also clearly demonstrates that, in an era when the rate of sea level rise is expected to increase, if we want to maintain Welsh beaches in their current condition then a major beach feeding project will be required. Such a campaign could deliver habitat, landscape, recreational and coastal defence benefits but only if additional finance and effective management systems were in place to enable this to occur. The pilot study recommends that further investigations be undertaken into possible sediment sources together with a more detailed economic appraisal, taking account not only of material extraction and transport costs but also the associated costs of regulatory compliance (environmental impact assessment and monitoring pre and post-works).
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