Now showing 1 - 2 of 2
  • Publication
    Spatial Distribution of Wave-by-Wave Overtopping at Vertical Seawalls
    (Coastal Engineering Research Council, 2020-12-28) ; ; ;
    Over the years, many physical and numerical modelling research has been carried out to investigate the wave-structure interactions and the resulting mean overtopping characteristics at sea defences. The most reliable empirical predication formulae for prediction of mean overtopping rates have been reported in the overtopping manual, EurOtop (2018). In addition to average overtopping rates, in recent years, the spatial distribution of overtopped water has become an important topic of research to understand the safe zone behind coastal defences. The existing empirical formulae for spatial distribution of overtopping provide conservative predictions, as it has been derived from the mean overtopping volumes. The extreme wave overtopping hazards in generally originate from individual overtopping events rather than the mean overtopping volumes. This study presents comprehensive laboratory investigations on the spatial distribution of wave-by-wave overtopping at vertical seawalls.
      161
  • Publication
    Effectiveness of Eco-retrofits in Reducing Wave Overtopping on Seawalls
    (Coastal Engineering Research Council, 2020-12-28) ; ; ;
    Terms 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.
      136