Hydraulic landscapes and irrigation systemsancient Uruk (Figure 2.3). In other words, not only did processes such as avulsion
create branching systems of channels, additional seemingly artificial cuts extended the
number of channels for both transport and irrigation.
In the twentieth century AD, before the massive damming of the rivers, the flow of
the Tigris and Euphrates was progressively reduced downstream by both evaporation
and the withdrawal of water for irrigation. Thus at Hit, on the Euphrates at the head
of the Mesopotamian plains, the discharge averaged 5,400 cubic metres per second,
whereas downstream at Nasriyah it was reduced to 1,740 (Potts 1997: 10). Despite this
diminution, which was probably less extreme during the third millennium BC, the
problem in the southern plains would have been to a) protect crops from excess water,
b) get rid of it by drainage, c) redistribute water via irrigation or take advantage of it
via flood-recession agriculture, and d) to utilize the abundant resources of the marshes.
Figure 2.3 Archaeological sites of the Ur III, Larsa and Old Babylonian periods and associated
channels in the area of Umma. This ganglion-like pattern illustrates the complexity of ancient
watercourses evident on air photographs and satellite images; the Shatt al-Gharraf currently flows
on a broad low levee from the Tigris to the north (re-drawn from Adams 2008, fig. 1).Modern
Shatt al-
GharrafBad TibiraNUruk
0 25km