TY - JOUR

T1 - Wave runup on composite beaches and dynamic cobble berm revetments

AU - Blenkinsopp, C. E.

AU - Bayle, P. M.

AU - Martins, K.

AU - Foss, O. W.

AU - Almeida, L. P.

AU - Kaminsky, G. M.

AU - Schimmels, S.

AU - Matsumoto, H.

N1 - Funding Information: The authors would like to acknowledge the support of everyone who assisted with the field and laboratory experiments reported here, in particular Jack Puleo, Brittany Bruder and Hannah Power (SALT), David Cottrell and Heather Weiner (NC), Gerd Masselink, Tim Poate and Kris Inch (WWH), Matthias Kudella, Isabel Kelly, Emily Gulson and Tom Beuzen (DR1 and 2). The SALT experiment was funded by the Engineering and Physical Sciences Research Council (EPSRC) grant EP/N019237/1, Waves in Shallow Water, awarded to Chris Blenkinsopp. WWH was funded by Engineering and Physical Sciences Research Council (EPSRC; EP/H040056/1). DynaRev1 received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 654110, HYDRALAB+. DynaRev2 was funded through a Research England Global Challenges Research Fund. Chris Blenkinsopp was supported by a Royal Academy of Engineering Leverhulme Trust Research Fellowship. Ollie Foss and Paul Bayle were supported by a PhD scholarship through the EPSRC CDT in Water Informatics: Science and Engineering (WISE). Kévin Martins acknowledges financial support from the University of Bordeaux, through an International Postdoctoral Grant (Idex, nb. 1024R-5030). Hironori Matsumoto was supported by U.S. Army Corp of Engineers (W912HZ192) and the California Department of Parks and Recreation, Natural Resources Division Oceanography Program (C19E0026).

PY - 2022/9

Y1 - 2022/9

N2 - The effects of climate change and sea level rise, combined with overpopulation are leading to ever-increasing stress on coastal regions throughout the world. As a result, there is increased interest in sustainable and adaptable methods of coastal protection. Dynamic cobble berm revetments consist of a gravel berm installed close to the high tide shoreline on a sand beach and are designed to mimic naturally occurring composite beaches (dissipative sandy beaches with a gravel berm around the high tide shoreline). Existing approaches to predict wave runup on sand or pure gravel beaches have very poor skill for composite beaches and this restricts the ability of coastal engineers to assess flood risks at existing sites or design new protection structures. This paper presents high-resolution measurements of wave runup from five field and large-scale laboratory experiments investigating composite beaches and dynamic cobble berm revetments. These data demonstrated that as the swash zone transitions from the fronting sand beach to the gravel berm, the short-wave component of significant swash height rapidly increases and can dominate over the infragravity component. When the berm toe is submerged at high tide, it was found that wave runup is strongly controlled by the water depth at the toe of the gravel berm. This is due to the decoupling of the significant wave height at the berm toe from the offshore wave conditions due to the dissipative nature of the fronting sand beach. This insight, combined with new methods to predict wave setup and infragravity wave dissipation on composite beaches is used to develop the first composite beach/dynamic revetment-specific methodologies for predicting wave runup.

AB - The effects of climate change and sea level rise, combined with overpopulation are leading to ever-increasing stress on coastal regions throughout the world. As a result, there is increased interest in sustainable and adaptable methods of coastal protection. Dynamic cobble berm revetments consist of a gravel berm installed close to the high tide shoreline on a sand beach and are designed to mimic naturally occurring composite beaches (dissipative sandy beaches with a gravel berm around the high tide shoreline). Existing approaches to predict wave runup on sand or pure gravel beaches have very poor skill for composite beaches and this restricts the ability of coastal engineers to assess flood risks at existing sites or design new protection structures. This paper presents high-resolution measurements of wave runup from five field and large-scale laboratory experiments investigating composite beaches and dynamic cobble berm revetments. These data demonstrated that as the swash zone transitions from the fronting sand beach to the gravel berm, the short-wave component of significant swash height rapidly increases and can dominate over the infragravity component. When the berm toe is submerged at high tide, it was found that wave runup is strongly controlled by the water depth at the toe of the gravel berm. This is due to the decoupling of the significant wave height at the berm toe from the offshore wave conditions due to the dissipative nature of the fronting sand beach. This insight, combined with new methods to predict wave setup and infragravity wave dissipation on composite beaches is used to develop the first composite beach/dynamic revetment-specific methodologies for predicting wave runup.

KW - Composite beach

KW - Dynamic cobble berm revetment

KW - Dynamic revetment

KW - Swash

KW - Wave reflection

KW - Wave runup

UR - http://www.scopus.com/inward/record.url?scp=85131681213&partnerID=8YFLogxK

U2 - 10.1016/j.coastaleng.2022.104148

DO - 10.1016/j.coastaleng.2022.104148

M3 - Article

AN - SCOPUS:85131681213

VL - 176

JO - Coastal engineering

JF - Coastal engineering

SN - 0378-3839

M1 - 104148

ER -