USING EXPERIMENTAL “SMART GRAVELS” FOR DETERMINING COARSE GRAVEL DISTRIBUTION ALONG THE DEAD SEA SHORE DURING BASE-LEVEL FALL

Continental shelves and slopes can emerge under global eustatic lowstands or during exceptional sea-level declines. Emergence of the high gradients of the continental slope can trigger across-shelf sediment transport and intensify coarse sediment flux from highstand to lowstand deltas. The redistribution of the coarse sediments in the receiving basin is affected by the action of waves and currents and the base-level lowering. Shelf/slope emergence to above Dead Sea levels, which have declined rapidly in the past decades, has been associated with such redistribution of coarse sediments at the lakeshore. This allows measuring directly the volumes of coarse sediments reaching the lakeshore annually, and the distribution of the gravels from the deltas and along shore. Annual deltas and beach berms are easily distinguished from each other as the lake-level declines ~1 m y^-1, leaving the abandoned delta above shore. We documented the annual and even single storm distribution of the gravels from their appearance in the stream mouth and their subsequent alongshore dispersal by waves and currents. We utilized a high-resolution, data-rich setup of instrumentation for determining (1) winds magnitude and direction, (2) waves and currents, (3) underwater movement of sediments by Remoted Operated Vehicle (ROV), and (4) real-time position and movements of the gravels using a novel system of accelerometers installed into the clasts, recording their movements during individual storm. Results provide initial glimpses into the relations between hydroclimatic parameters and the gravel deposition and the causes of the observed preferred dispersion of the gravel northward of the channel mouth. Modelling of the coarse particles movement, aided by the new information from these “Smart Gravels”, will enable examining the controlling parameters and their thresholds, involved in shaping the coastal environment of a basin experiencing forced regression.