Geodiversity as a key for human survival in the harshest deserts on earth
Dr. Yoav Avni
Geological Survey of Israel
The present aridity of the desert zone of the Middle East was established during the last 2 million years, coeval with the presence of human societies in this region.
According to its long archeological record, this desert zone is holding evidence of hunters, gathers, pastoralists and farmers that subsisted in arid to hyper-arid climate, demonstrating its ability to support human societies over long time. In this regard, the Negev and Sinai deserts are among the harshest deserts on earth receiving only 25-130 mm/y. Despite these climatic conditions, the existence of human societies is documentation in the archeological record from the Early Paleolithic to the present time.
The capability of human societies to survive in harsh environments is very much depended on the utilization of the natural conditions, such as the interaction between the geodiversity, landscape evolution processes and climate. In the hyper-arid Sinai desert, water availability is depended very much on good transformation of the occasional precipitations to runoff, stored for long periods below surface in alluvial beds deposited along the streams. The coexistence of water resources with the abundant eatable acacia trees made this harsh environment suitable for herds of Gazelle, Ibex and Ostrich, tracked by small groups of hunters. These natural conditions were utilized by pastoral societies since ancient times, including by the present Bedouins. The utilization of these water resources for agriculture was limited in the past to profitable crops, replaced at present by the cultivation of plants used for drugs, such as opium.
In the Negev and Southern Jordan deserts, numerous cisterns were dug in preferred geological formation such as the Disi sandstone and the Menuha chalk, enabling long-term water storage. Part of these cisterns were dug in vicinity to the caravan road connecting Arabia and the Mediterranean coast. These cisterns, together with several shallow wells located along the main streams, are constructing a net of permanent and reliable water resources supporting pastoral and agricultural desert societies.
On a wider scope, other harsh deserts, such as the Atacama and the Taklimakan, are gaining from permanent water resources originated in high mountain ranges such as the Andes and the Tian Shan, which contain everlasting glaciers. The desert societies that lived in these regions were sustained for long periods, gaining from their spatial flexibility and their access to these permanent resources.
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