HOLOCENE WATER AND SOIL MANAGEMENT IN ARID LANDS AND THE ORIGIN OF PRESENT-DAY OASIS

The formation of oases in the arid lands of the Old World is one of the major geomorphological processes occurring since the middle Holocene. These landscape units formed due to the progressive reduction of water availability in response to the withdrawal of the summer monsoon over the deserts of North Africa, the Levant, and Arabia, ultimately driven by decreased insolation. The tempo and mode of this process vary slightly in each region, but the result is the creation of a specific ecological niche able to sustain life thanks to residual water reservoirs. Besides the natural geomorphological processes, human activity has greatly contributed to the expansion and preservation of oases, shaping their present-day appearance. In some cases, however, overexploitation of natural resources has led to the disappearance of oases. Since the mid-late Holocene, human communities have concentrated around oases and experimented with many different strategies to exploit fertile soils and implement water-harvesting techniques. In this context, the introduction of diverse land management techniques has greatly contributed to shaping the present-day appearance of oases and, in some cases, was crucial in creating them. For these reasons, oases can be considered anthropogenic ecosystems. This contribution will report on several pieces of geo-archaeological evidence for the anthropogenic creation of oases ecosystems in different physiographic units of arid lands. Moreover, it will explore how human communities supported the maintenance of oases through methods of water and soil management, as detected at several sites in the Sahara and the Arabian Peninsula.