2.1 Test sites
To quantify and assess the capability of this novel technique to estimate beach-face slopes, eight diverse locations across three continents are considered. The selected sites exhibit a large range of beach-face slope, grain size and tidal range. Among the eight sites, two are macrotidal beaches (Slapton Sands, UK and Cable Beach, Australia), three are mesotidal beaches (Tairua, New Zealand, Torrey Pines, USA and Ensenada, Mexico), and three are microtidal beaches (Narrabeen and Moruya-Pedro, Australia and Duck, USA). The sites were selected based on availability of repeat in situ topographic surveys to calculate the temporal-average beach-face slope, defined for each cross-shore transect from mean sea level (MSL) to mean high water springs (MHWS). TableĀ 1 summarises the key characteristics at each site (average beach slope, mean spring tidal range, mean deep-water significant wave height and sediment grain size) and the geographical locations are presented in Figure S1 (Supporting Information). The broad range of temporal-average beach-face slopes range from 0.025 at Cable Beach to 0.14 at Slapton Sands.