Composite Beaches - Can we protect our coastlines by mimicking nature?
Lead Research Organisation:
University of Bath
Department Name: Architecture and Civil Engineering
Abstract
Project Background
Composite beaches consist of a lower foreshore of sand and a naturally occurring permanent or semi- permanent backshore ridge of cobbles, and are ubiquitous beach environments in the UK, USA and NZ. These beaches are known to be highly stable because they combine a dissipative sand slope and a reflective cobble berm, which represent the two most stable end members in the classification of beach morphodynamics. Furthermore, when a permanent cobble ridge exists it can play a significant natural coastal protection role, stabilising the upper beach and providing overtopping protection to the hinterland. As a result, constructed cobble berms (or dynamic revetments) designed to mimic composite beach cobble ridges are being trialled to provide coastal defence at vulnerable beaches on the US West Coast with some success. Despite the common occurrence of composite beaches and their value as a natural form of coastal defence they have received very little attention in academic literature with almost no composite beach- specific studies being undertaken to date. As a result, understanding of composite beach processes such as cross- and longshore cobble transport, wave runup and overtopping of cobble ridges and response to sea level rise is minimal.
Project Aims and Methods
This project aims to fill this identified research gap and undertake one of the first detailed studies into composite beach behaviour. This work will enhance understanding of this valuable beach type and gain insight which will enable the design nature-based coastal defence structures which mimic composite beach behaviour to provide sustainable and low-cost coastal protection. This will be achieved through the following activities:
1. Analysis of existing historical topographic data to elucidate the medium to long-term variability of composite beaches and their resilience to extreme storms and storm sequences. This will include a global assessment of composite beach stability using satellite imagery via the new "CoastSat" satellite coastal monitoring tool.
2. Analysis of data from the recently installed (June 2021) permanent Lidar station at Borth beach which provides beach profiles and wave runup data continuously at 1 Hz. This analysis will focus on storm erosion and post-storm response.
3. Field experiments using a newly-developed, wave-by-wave cobble tracking methodology at 2 or more composite beaches in Wales and/or USA to better understand the short term variability of composite beach ridges and the mobilisation of individual cobbles.
4. Test and potentially develop the existing state of the art XBeach-G coastal model to predict morphology changes on composite beaches. If successful, this will improve our ability to assess the vulnerability of composite beaches to increasing storminess and provide a tool for the design of dynamic revetment coastal protection structures.
Composite beaches consist of a lower foreshore of sand and a naturally occurring permanent or semi- permanent backshore ridge of cobbles, and are ubiquitous beach environments in the UK, USA and NZ. These beaches are known to be highly stable because they combine a dissipative sand slope and a reflective cobble berm, which represent the two most stable end members in the classification of beach morphodynamics. Furthermore, when a permanent cobble ridge exists it can play a significant natural coastal protection role, stabilising the upper beach and providing overtopping protection to the hinterland. As a result, constructed cobble berms (or dynamic revetments) designed to mimic composite beach cobble ridges are being trialled to provide coastal defence at vulnerable beaches on the US West Coast with some success. Despite the common occurrence of composite beaches and their value as a natural form of coastal defence they have received very little attention in academic literature with almost no composite beach- specific studies being undertaken to date. As a result, understanding of composite beach processes such as cross- and longshore cobble transport, wave runup and overtopping of cobble ridges and response to sea level rise is minimal.
Project Aims and Methods
This project aims to fill this identified research gap and undertake one of the first detailed studies into composite beach behaviour. This work will enhance understanding of this valuable beach type and gain insight which will enable the design nature-based coastal defence structures which mimic composite beach behaviour to provide sustainable and low-cost coastal protection. This will be achieved through the following activities:
1. Analysis of existing historical topographic data to elucidate the medium to long-term variability of composite beaches and their resilience to extreme storms and storm sequences. This will include a global assessment of composite beach stability using satellite imagery via the new "CoastSat" satellite coastal monitoring tool.
2. Analysis of data from the recently installed (June 2021) permanent Lidar station at Borth beach which provides beach profiles and wave runup data continuously at 1 Hz. This analysis will focus on storm erosion and post-storm response.
3. Field experiments using a newly-developed, wave-by-wave cobble tracking methodology at 2 or more composite beaches in Wales and/or USA to better understand the short term variability of composite beach ridges and the mobilisation of individual cobbles.
4. Test and potentially develop the existing state of the art XBeach-G coastal model to predict morphology changes on composite beaches. If successful, this will improve our ability to assess the vulnerability of composite beaches to increasing storminess and provide a tool for the design of dynamic revetment coastal protection structures.
Organisations
People |
ORCID iD |
| Christopher Blenkinsopp (Primary Supervisor) | |
| Alex MINNIGIN (Student) |
Studentship Projects
| Project Reference | Relationship | Related To | Start | End | Student Name |
|---|---|---|---|---|---|
| NE/S007504/1 | 01/10/2019 | 30/11/2027 | |||
| 2750093 | Studentship | NE/S007504/1 | 01/10/2022 | 31/03/2026 | Alex MINNIGIN |