Ancient through mid-twentieth century runoff harvesting agriculture in the hyper-arid Arava Valley of Israel

Many archaeological remains of runoff harvesting agricultural systems have been discovered throughout the hyper-arid central Arava Valley in southern Israel. The remains include stone terraces and conduits in 12 wadis (ephemeral stream channels). Other agriculture-related stone-made infrastructures included a rounded threshing floor and many livestock enclosures. Additionally, many farming-related hand tools and pottery fragments were also found. The pottery and tools were dated to a chronological sequence, ranging between the Late Neolithic (6450–4550 BCE) and recent Bedouin (until the mid-20th century) ages. Some of the archaeological findings suggest that barley and wheat were the dominant crops. This highlights the importance of runoff farming for the subsistence economy of ancient populations, playing a central role in the smallholder, mixed crop-livestock system's adaptation strategy. Agro-hydrological assessment of runoff harvesting potential under the current climatic conditions was conducted for selected six terraced fields. For conducting this, data on precipitation for a 16-year period (1999/00 to 2015/16) was obtained from two meteorological stations. Then, modeling of both alluvial- and fluvial- runoff processes was performed for each of the six terraced fields. Combining the alluvial and fluvial processes revealed that either 6-mm rainstorms, which occur on an average of once every year, or 10-mm rainstorms, which take place on an average of once every 1.8–3.2 years, would allow cereal production in only one of the terraced fields. Rainstorms of 20 mm, which took place only once during the 16-year period, would allow successful cropping in five of the terraced fields. Insights of this study concur with other studies, which revealed the considerably drier regional conditions at present compared to those in ancient times, and even compared to those in the mid-20th century.