AbstractTerms such as 'nature-based', 'living shoreline', 'green infrastructure' and 'ecological engineering' are increasingly being used to reflect biomimicry-based engineering measures in coastal defences. Innovative interventions for nature-based sea defences have included the retrofitting of man-made water filled depressions or 'vertipools' to existing seawalls (Hall et al., 2019; Naylor et al., 2017) and the addition of artificial drill-cored rock pools to intertidal breakwaters (Evans et al., 2016). Through their capacity to retain water, such measures serve to enhance biodiversity in the built environment (Browne and Chapman, 2014). Evans et al. (2016) for example, experimentally demonstrated that the introduction of artificial rock pools to an intertidal granite breakwater enhanced the levels of species richness compared to those observed on plain surfaces of the breakwater. Notwithstanding these biological benefits, the impetus for incorporation of ecologically friendly measures to existing defences remains low (Salauddin et al., 2020a). This situation could potentially change should it be shown that the addition of 'green' measures to sea defences could enhance wave attenuation and reduce wave overtopping as well as wave pressures on the coastal defence structures. This paper describes small-scale physical modelling investigations of seawalls and explores reductions in wave overtopping that could be realised by retrofitting sea defences with 'green' features (such as 'vertipools'). Surface protrusions of varying scale and density are used in the physical modelling to mimic 'green' features and the results from measurements of overtopping are benchmarked to reference conditions determined from tests on a plain seawall.
Abolfathi, Dong, Borzooei, Yeganeh-Bakhtiari, Pearson (2018): Application of Smoothed Particle Hydrodynamics in Evaluating the Performance of Coastal Retrofits Structures. In: Proceedings .of Coastal Engineering, 1(36). doi: https://doi.org/10.9753/icce.v36.papers.109.
Allsop, Bruce, Pearson, Besley (2005): Wave overtopping at vertical and steep seawalls. In: Proceedings of the International Conference on Maritime Engineering, Institution of Civil Engineers, 158(MA3), pp. 103–114.
Browne and Chapman (2014): Mitigating against the loss of species by adding artificial intertidal pools to existing seawalls. Marine Ecology Progress Series, 497, pp. 119-129).
Dong, Salauddin, Abolfathi, Tan, Pearson (2018). The Influence of Geometrical Shape Changes on Wave Overtopping: a Laboratory and SPH Numerical Study. Coasts, Marine Structures and Breakwaters 2017, pp. 1217-1226. https://doi.org/10.1680/cmsb.63174.1217
Dong, Abolfathi, Salauddin, Tan, Pearson (2020). Enhancing Climate Resilience of Vertical Seawall with Retrofitting - A Physical Modelling Study. Applied Ocean Research. Applied Ocean Research, 103, 102331. https://doi.org/10.1016/j.apor.2020.102331
EurOtop (2018): Manual on wave overtopping of sea defences and related structures. Second Edition. www.overtopping-manual.com.
Evans, Firth, Hawkins, Morris, Goudge, Moore (2016): Drill-cored rock pools: an effective method of ecological enhancement on artificial structures. Marine and Freshwater Research, 67(1), pp. 123-130.
Franco, De Gerloni, Van Der Meer (1994): Wave overtopping on vertical and composite breakwaters. In: Proceedings of the 24th ICCE, ASCE, Kobe, Japan, pp. 1030-1045.
Hall, Herbert, Britton, Boyd, George (2019): Shelving the Coast With Vertipools: Retrofitting Artificial Rock Pools on Coastal Structures as Mitigation for Coastal Squeeze.
Frontiers in Marine Science, 6, no. 456.Mansard, Funke (1980): The measurement of incident and reflected spectra using a least squares method. Coastal Engineering, 154–172.
Naylor, Kippen, Coombes, Horton, Macarthur, Jackson (2017): Greening the Grey: a framework for integrated green grey infrastructure (IGGI), University of Glasgow report.
Salauddin, Broere, Van der Meer, Verhagen, Bijl (2017): First Tests on the Symmetrical Breakwater Armor Unit Crablock. Coastal Engineering Journal, 59 (4), 1-33. https://doi.org/10.1142/S0578563417500206
Salauddin, Pearson (2018): A laboratory study on wave overtopping at vertical seawalls with a shingle foreshore. Coastal Engineering Proceedings, 1(36), waves.56. https://doi.org/10.9753/icce.v36.waves.56
Salauddin, Pearson (2019a): Wave overtopping and toe scouring at a plain vertical seawall with shingle foreshore: A Physical model study. Ocean Engineering 171,286-299. https://doi.org/10.1016/j.oceaneng.2018.11.011
Salauddin and Pearson (2019b). Experimental Study on Toe Scouring at Sloping Walls with Gravel Foreshores. Journal of Marine Science and Engineering, 7, 198. https://doi.org/10.3390/jmse7070198
Salauddin and Pearson (2020): Laboratory investigation of overtopping at a sloping structure with permeable shingle foreshore. Ocean Engineering, 197 (1), 1-13. https://doi.org/10.1016/j.oceaneng.2019.106866
Salauddin, O’Sullivan, Abolfathi, Pearson (2020): Extreme wave overtopping at ecologically modified sea defences. 22nd EGU General Assembly 2020, EGU2020-6162. https://doi.org/10.5194/egusphere-egu2020-6162
Van der Meer and Bruce (2014): New physical insights and design formulas on wave overtopping at sloping and vertical structures. Journal of Waterway, Port, Coastal, and Ocean Engineering 140(6): 04014025. https://doi.org/10.1061/(ASCE)WW.1943-5460.0000221
Yeganeh-Bakhtiary, Houshangi, and Abolfathi (2020): Lagrangian two-phase flow modeling of scour in front of vertical breakwater. Coastal Engineering Journal, 62:2, 252-266, https://doi.org/10.1080/21664250.2020.1747140