Routledge Revivals: Medieval Science, Technology and Medicine (2006) by Glick Thomas F.; Livesey Steven J.; Wallis Faith

Author:Glick, Thomas F.; Livesey, Steven J.; Wallis, Faith
Language: eng
Format: epub
Publisher: Taylor and Francis

Mediterranean Drainage

The Romans had undertaken some successful drainage schemes, particularly in the Po Valley. Fields were crisscrossed with trenches running transversely to field furrows and which emptied into drainage canals. Roman law required collective maintenance of dikes and trenches forming a common drainage system. Between the eleventh and thirteenth centuries there was considerable diking and drainage canal construction in the Po Valley. Cistercians, in particular, were prominent in monastic drainage projects in Tuscan wetlands particularly in the twelfth century, and towns such as Pistoia, Prato, and Siena reclaimed their marshy plains by drainage in the thirteenth century.

Littoral marshlands of the Mediterranean presented different opportunities. Historically there have been four distinct strategies for the use of littoral wetlands. The first is hunting and gathering as an activity complementary to agriculture. This is the origin of the Valencian paella, all of whose ingredients (rice, rabbit, and shellfish) come from littoral wetlands. Second are local extensions of productive activities at the edges of wetlands, such as creating pasture with local dikes. The third is conversion to rice paddies or huerta (by extending already existing canal systems). The fourth is to open towards the sea and create small harbors or sea channels (Horden and Purcell, 188–189). In medieval Valencia, all four strategies were deployed simultaneously. Trenches were dug into the marshlands (marjals) east of the city to drain them. Then irrigation canals were extended from the already irrigated areas close to the city. Water flowing in surface channels, however, had the effect of raising the water table with the result that the channels would disintegrate unless constantly maintained. The marjals were reclaimed from around 1386 when the bishop reduced tithes on property there to entice settlement. The fields there, he said, had become marshy and barren due to the ruin and canals and drainage ditches owing to the low density of population. The project was successful until the drought of 1412–1415, when settlement retreated again. The net short-term result of such projects was the extension of marsh, because an abandoned marsh with irrigation canals leading into it is marshier than in its natural state.

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