Aqueducts


 Jerusalem Aqueduct Graphic


"The other “vein” (feeding Solomon’s Pools) is the Arrub Aqueduct. It gatheredthe waters of a group of springs lying between Bethlehem and Hebron and then,
following the contours of the ridges and wadis, wound through the Judean hills for an a stounding 40 km (a straight-line distance of 10 km), at an equally amazing
gradient of only 0.09% (1:1100+)! For much of its length it was a simple channel hewn into the bedrock slopes plastered and capped with stone slabs.
Obstacles were overcome via two methods: (1) tunneling through some ridges and (2) elevating the channel on a stone wall/dam in order to cross wadis. The dating of the Arrub Aqueduct is not certain, but it is a good candidate for the aqueduct mentioned by Josephus for which Pontius Pilate appropriated Temple funds, thereby sparking riots in Jerusalem (Antiquities 18). It seemingly was re-built in the Mamluk period and finally went out of service in Ottoman times. (Its great length made it especially susceptible to damage or clogging, unauthorized tapping of the water, and the pilfering of cap-stones.

Another "artery" (coming from Solomon's pools) is the Upper Aqueduct of Jerusalem. It began at Solomon’s Pools, ran northward, close to the watershed line (at a higher elevation than its “Lower” counterpart); it skirted Bethlehem on the west side, closely paralleled today’s Hebron Road, and apparently had as its destination “Hezekiah’s Pool” in the Upper City. Its length was 14 km, with an average gradient of 0.28% (1:357). Its best-known remains are a still-visible section of stone pipe (a siphon) across a shallow valley near Rachel’s Tomb. Based on inscriptions of the 10th Roman Legion on the pipe segments, the Upper Aqueduct was long dated to the Late Roman period, however it is now clear there was an earlier, parallel, high-level aqueduct section (i.e., elevated on arches), an earlier solution to the same topographical problem, i.e. transmission of the water across the valley. Several surviving piers of this high-level section were discovered and documented in the 1980s and ‘90s but were later removed in a building project. Thus, the Upper Aqueduct is now thought to have been Herodian in its earliest phase, then re-built in the Late Roman period, and it may have gone out of use after the Byzantine era."

Information found at
http://israelpalestineguide.files.wordpress.com/2010/07/lower-aqueduct-wpics.pdf