Speaking of Roman hydrology, most people point to the aqueducts which were truly marvels of precision engineering.
However, there is something even more interesting in Spain. The Romans found a mountain that contained deep gold seams. In order to get it out, they constructed a 10 miles long aqueduct from a mountain lake to the top of the mountain, then drilled into the top and used the water from the aqueduct as a water drill to hollow out the mountain’s gold seams.
I saw this on Discover or the History channel once and found a webstie about it on Google but I can’t remember the name of the site. Unfortunately, it is in Spanish.
[snip] The remains at Las Medulas and in surrounding areas show badland scenery on a gigantic scale owing to hydraulicking of the rich alluvial gold deposits. Las Medulas is now a UNESCO World Heritage site. The site shows the remains of at least seven large aqueducts of up to 30 miles in length feeding large supplies of water into the site. The gold-mining operations were described in vivid terms by Pliny the Elder in his Naturalis Historia published in the first century AD. Pliny was a procurator in Hispania Terraconensis in the 70’s and must have witnessed for himself the operations. The use of hushing has been confirmed by field survey and archaeology at Dolaucothi in South Wales, the only known Roman gold mine in Britain. [end]
http://en.wikipedia.org/wiki/Hydraulic_mining#Ancient_development
pic:
http://www.superstock.com/stock-photos-images/1566-0102674