Climate forcing and shifts in water management on the Northwest Arabian Peninsula (mid-Holocene Rasif wetlands, Saudi Arabia)

Abstract

The mid-Holocene climate of Northwest Arabia is characterised by a significant increase in aridity which gave rise to changes in water management strategies including sophisticated techniques at later stages. The Rasif site, situated in Northwest Saudi Arabia, reveals a Late Neolithic society with multi-roomed domestic structures (1st phase, 6th millennium BCE, before the current era). At Rasif site the sediments of an endorheic basin (qa) show a minimum in salinity during this 1st phase. The 2nd phase is characterised by a pastoral ‘Chalcolithic’ watering and ‘Chalcolithic’ burial location of the 5th millennium BCE with wells, complex trough systems, and initial, probably coexistent grave structures. During this 2nd phase the qa deposits show already a slight increase in salinity. We have evidence for a sub-surface water-rich sand layer within the qa that was exploited by shallow wells. During the subsequent 3rd phase the number of pastoral ‘Chalcolithic’ D-shaped grave structures within the qa increased, probably co-existing with deepened wells and complex trough systems. At that time the qa is covered by an almost impermeable saline clay layer. The 4th phase is characterised by a culturally yet to identify pastoral post-‘Chalcolithic’ watering location with single small troughs. The final 5th phase represents a culturally unidentified pastoral post-’Chalcolithic’ to sub-recent water harvesting location with complex dam systems, which were probably modified numerous times. The dam systems allowed to flooding the qas for several months, providing (sub-) surface water in the nowadays Northwest Arabian desert.