WireWall project numerical wave overtopping volume estimates, for profiles in 1996 and 2017. Estimates are calculated at Crosby Hall Road Carpark (north of Liverpool UK) for joint wave and water level conditions that represent the return period curves in Liverpool Bay developed in 2011.

Numerical wave overtopping volume estimates from the BayonetGPE wave overtopping tool associated with the EurOtop (2018) manual and modelled wave and water level conditions at the toe of the structure transformed from nearshore national monitoring networks using the SWAN model. Mean, upper and lower 1st and 2nd standard deviation wave overtopping volumes are estimated by BayonetGPE (generated by HR Wallingford, October 2019) for the Hall Road Car Park, Crosby Beach survey profile (reference: 11A02250). The data are associated with joint wave and water level conditions at the Liverpool Bay Wave Buoy Location that form the 1 in 1 year to 1 in 200 year return period curves in a joint probability analysis for the North West Coastal Group delivered by Halcrow in 2011. These return period curves represent the conditions to design new coastal schemes and analyse event severity. The numerical estimates of overtopping were generated using: beach surveys (available from Channel Coastal Observatory) from 24th February 2017, 4th April 2017, 4th October 2017 and 1 September 1996; a laser scan of the sea wall collected 11th December 2013 (available from Sefton Council); Seazone bathymetry from 05/12/2014, originally collected by the UK Hydrographic Office at 1 arc second. The coastal conditions were transformed to the toe of the existing structure using the 3rd generation spectral wave model SWAN. The bottom friction was set to use bed ripples and a sediment size of 0.23 mm (the Median grain size, d50, for the upper beach at Crosby, KPAL 2010). BayonetGPE was then used to estimate the resulting overtopping discharges.