How does Coastal Gravel get Sorted under Stormy Longshore Transport? *

Wave storms transport and sort coarse gravel along coasts. This fundamental process is important under changing sea-levels and increased storm frequency and intensity. However, limited information on intra-storm clast motion restricts theory development for coastal gravel sorting and coastal management under stormy longshore transport. Here, we use 'smart boulders' equipped with loggers recording underwater, real-time, intra-storm clast motion, and measured longshore displacement of varied-mass marked boulders during storms. We utilize the unique Dead Sea setting where rapidly falling water levels allow isolating boulder transport and sorting during individual storms. Guided by these observations, we developed a new model quantifying the critical wave height for a certain clast mass entrainment. Then, we obtained an expression for the longshore clast displacement under the fluid-induced pressure impulse of a given wave. Finally, we formulate the sorting enforced by wave-height storm distributions, demonstrating how sorting is a direct manifestation of regional, turned-into-local hydroclimatology.