Late Quaternary palaeohydrology, aeolian dynamics and erosion rates recorded in a small, dune-dammed, arid dunefield margin playa

Small endorheic basins at the arid, northwestern Negev desert dunefield margin were hypothesized to preserve finely resolved and quasi-continuous archives of climate‑driven sediment dynamics. Two 7.5‑m deep cores from the Givat Hayil dune‑dammed playa (0.047km²) captures sedimentation processes and erosion rates of a small, ~2 km² basin, characterized by ~1 short-lived flood per annum. A multi‑proxy approach combined laser‑diffraction grain‑size analysis and imaging, X‑ray fluorescence geochemistry, and portable-OSL (port‑OSL) profiling to diagnose the sediments, identify accumulation trends, delineate stratigraphic boundaries and target samples for OSL dating.

The cored sequence documents transitions between fluvial to aeolian dominated environments, from the onset of MIS-3 until today, and mainly since the Younger Dryas (YD). Basal, well‑bedded silt loams dating to the early MIS-3 suggest floodplain deposition of up-basin-sourced, primary, MIS-6-MIS-2 (calcic) loess deposits, indicative of initial and enhanced basinal loess erosion evolving into hyper-concentrated flows. A long MIS-3 - YD hiatus suggests significant decrease in loess erosion rates. YD - early Holocene aeolian sand influx led to the playa-forming  dune dam. During the Holocene, the playa efficiently trapped sediments undergoing varying upbasin fluvial erosion rates and ongoing dustfall, punctuated by anthropogenically-induced Roman-Byzantine sand mobilization. Thin units with diluted aeolian sand content probably indicating rapid pulses of eroded up-basin loess delivery driven by high-intensity rain events are interpreted to document major and altogether, evenly distributed, ~1:1,000 yr recurring floods.

Changing sediment accumulation rates appears to capture a complete and fluctuating erosion trajectory of up-basin loess—from a MIS-3 loess‑loaded landscape to a present loess-starved basin. Inversed magnitude-lower loess erosion rates along the Late Pleistocene–Holocene transition in relation to the Holocene, despite higher up-basin loess availability, probably reflects a moister Late Pleistocene that enhanced vegetation and crust development, that in turn, increased loess preservability. Three-fold larger late Holocene accumulation rates in relation to the early Holocene, despite depleting up-basin loess availability, may be a result of higher erosion rates due to more high-intensity rainfall events, in line with gradually increasing aridity.

Altogether, this underrecognized, high‑resolution archive demonstrates how sediment archives of small, dunefield fringe endorheic basins can serve to resolve the timing, magnitude, and mechanisms of both aeolian and fluvial processes, in particular extreme floods and erosion rates, in arid and hyper-arid environments.