High-resolution, large-scale laboratory measurements of a sandy beach and dynamic cobble berm revetment

Abstract

High quality laboratory measurements of nearshore waves and morphology change at, or near prototype-scale are essential to support new understanding of coastal processes and enable the development and validation of predictive models. The DynaRev experiment was completed at the GWK large wave flume over 8 weeks during 2017 to investigate the response of a sandy beach to water level rise and varying wave conditions with and without a dynamic cobble berm revetment, as well as the resilience of the revetment itself. A large array of instrumentation was used throughout the experiment to capture: (1) wave transformation from intermediate water depths to the runup limit at high spatio-temporal resolution, (2) beach profile change including wave-by-wave changes in the swash zone, (3) detailed hydro and morphodynamic measurements around a developing and a translating sandbar.

Remote Sensing of Wave Overtopping on Dynamic Coastal Structures

“…DynaRev1 (1DR) is described in detail in [10,23] and was completed during August and September 2017. In summary, a dynamic cobble berm revetment with an initial slope of 1:6 (tanβ = 0.167) was constructed using well-sorted, rounded cobbles (D 50 = 63 mm, D 85 /D 15 = 1.32, porosity, ∅ = 0.41) on a sand beach profile (D 50 = 0.33 mm) which had developed after 20 h of constant wave forcing (H s = 0.8 m, T p = 6.0 s) (see Figure 1a).…”

A new approach for scaling beach profile evolution and sediment transport rates in distorted laboratory models

“… GWK experiment: the primary aim was to test the coastal protection performance of a dynamic cobble berm revetment installed on a sandy beach under erosive waves and water level changes. The performance of the revetment was assessed by comparing beach profiles, shoreline retreat and runup with and without the structure under the same hydrodynamic forcing [8,23]. The current paper primarily focusses on test cases with a sand-only beach (SB0 in [8]) except for section 6.2.…”

“…The performance of the revetment was assessed by comparing beach profiles, shoreline retreat and runup with and without the structure under the same hydrodynamic forcing [8,23]. The current paper primarily focusses on test cases with a sand-only beach (SB0 in [8]) except for section 6.2.…”

“…𝑧 * = 𝑧 𝑐𝑜𝑠𝛽 𝑅 (8) with β the angle of the initial beach slope, x and z the local coordinates and x* and z* the new dimensionless coordinates. Note that in Peregrine and Williams (2001) [21], R=2A, so there is a factor two difference in the method presented here compared to the scale presented in Peregrine and Williams (2001) [21].…”

“…While these two studies provided new insights into beach profile evolution under rising water levels, the scaled nature of the experiments means that the direct application of these flume-based observations to prototype scale behaviour is unclear. This paper aims to develop a new scaling methodology for comparing beach profiles of distorted experiments, using three different datasets: a novel prototype-scale laboratory dataset (obtained as a component of the DynaRev experiment [8]), and two existing medium-scale model datasets (obtained from the experiments described in Atkinson et al (2018) [6] and Beuzen et al (2018) [7]). While each dataset measures beach profile response to erosive waves and increasing water levels, they differ in terms of scale and hydrodynamics.…”