Integrating local shoreface changes and regional hydrographic data to establish a regional sediment budget

Programme website: http://inspire-dtp.ac.uk

Project Rationale:
Mixed, shingle barrier beaches have high natural capital value due to their importance for flood defence amongst other roles. Despite this, little is known about the detailed processes of sediment transfer between shore faces and the nearshore zone in marine embayments, with existing research limited to very small areas or coarse scale sediment budget studies. This is because such research is usually underpinned by high resolution repeat bathymetry which is notoriously difficult to collect in the nearshore zone. This CASE studentship will address this research gap using state-of-the-art shallow bathymetric data collection technology at Pevensey Bay, East Sussex. Pevensey is an ideal location as it represents a crucial asset in flood defence and coastal risk management along the East Sussex coastline, protecting the low-lying Pevensey Levels, with designated wetlands as well as thousands of vulnerable properties (many built at the crest) and coastal infrastructure. A better understanding of the dynamics of mixed shingle barriers generally, and Pevensey barrier specifically, is crucial to inform future management, especially as the current protection scheme approaches its end. Therefore, the aim of this project is to describe shoreface behaviour in the cross-shore and alongshore dimensions at high spatial and temporal resolution, to inform a local sediment budget. This will allow new insight into how local bedforms drive beach sediment dynamics through interactions with the wave regime.

Methodology:
Novel, rapid shallow water (up to 5 m depth) survey techniques will be coupled with existing CCO multi-beam bathymetry datasets; and historic, monthly records of beach profiles, to describe alongshore and cross-shore beach morphology and shore-face dynamics. The new survey work will aim to capture the bed changes in conjunction with wave data from the bay, providing a local description of sediment exchanges which will be used to implement a suitable shoreface model. Some regional investigation of sediment sources and background suspended sediment concentration will also be needed. This data will be used with the existing detailed swathe/multi-beam bathymetry and beach survey data to establish a geomorphological interpretation at a regional scale. A novel approach to estimating the regional sediment budget will then be tested, for the bay area, by integrating the results from the local and regional investigations.
Specific objectives are to:
a) Develop and apply novel, high-speed survey techniques to map the very-shallow nearshore (see Leyland et al., 2017).
b) Asses changes in shore-face morphology to infer sediment transport pathways
c) Define cross-shore and long-shore sediment fluxes to construct a local sediment budget for Pevensey bay that links beach roughness with driving wave regimes.

Training:
The INSPIRE DTP programme provides comprehensive personal and professional development training alongside extensive opportunities for students to expand their multi-disciplinary outlook through interactions with a wide network of academic, research and industrial/policy partners. The student will be registered at the University of Southampton and hosted at Ocean and Earth Science.

Specific training will include: The student will receive training in the deployment of state-of-the-art survey and monitoring equipment and laboratory sediment analysis techniques within Geography and from the Environmental Sensing @ Southampton (ES@S) facility, including unmanned aerial vehicles, Mobile Laser Scanning and MultiBeam Echo Sounding equipment. Further training will provide expertise in the processing of these large, complex data sets. Local context and application advice, a rich set of historical data and further background to coastal sediment systems will be provided by PCDL.