Iron Age water management in the northern Negev

MITZPE RAMON, ISRAEL–This region has a very deep human history, and some of it is evident in subtle changes to the landscape itself. Throughout the northern Negev are simple stone structures that are sometimes called “Davidic forts” after King David of Israel. They are, though, a lot more mysterious and difficult to date. They are usually associated with cisterns and water systems, and so they may have indeed been guardposts of some kind. Who exactly made these buildings and the water infrastructure is unclear. All we can say is that they are Iron Age and show an early agricultural people who had skills in collecting and managing the scarce water resources of this area. We saw evidence of them today in the field north of Mitzpe Ramon. Above you see Yoav and Melissa walking by one of these open cisterns cut into Upper Cretaceous limestone (the Vroman Bank of the Ora Formation) and then dug below in shale and claystone.

The hillsides to the sides and above these cisterns have long ditches lined with slabs of limestone on their downward sides. These were designed to catch runoff water from the slopes above and direct it to the open cistern below. Some of these ditch-and-rock channels stretch for kilometers.

Here a ditch heads to a large cistern, recognizable immediately by the sediment tailings dug out of the hole. This system takes advantage of the heavy and infrequent rains in the northern Negev. Sheetflow and water in small natural channels is captured and sent along the gentle gradient to the cistern below. By keeping the water from flowing too fast these early engineers minimized erosion of their channels.

This is the second cistern we saw today. It is many meters deep and could have held a great deal of water year-round. Bedouin herders today still use some of these cisterns for their flocks.

The later Nabateans elaborated upon these innovations and made roofed cisterns to reduce evaporation (which is 2.5 meters of water per year in Mitzpe Ramon). Sometimes they dug their cisterns into solid limestone rather than shale so they could have a small top opening and large covered container below.

As I write this the wind howls and rare rain is falling on the Negev. These rock systems are still channeling water after 3000 years!