"كتيّب بلاد الرافدين. المجلد I. ١٩١٨" [‎١‎٥‎٨] (٥٦٨/١٦٧)

158
IRRIGATION OF IRAK
the end of the Sassanian age, run approximately on its present
course. At the beginning of the seventh century a.d . abnormal
floods breached the Tigris dykes, the water spilt south and south
west towards the lower Euphrates, and eventually the main stream
of the Tigris took to the course of the present Shatt el-Hai. In the
time of the Caliphs there was a good deal of irrigation from the
Tigris between El-Madayyah (on or near the site of the present
Kut el-Amara) and the city of Wasit, about forty miles to the
south. Below Wasit the Tigris emptied into the Great Swamp. In
the course of the sixteenth century the Tigris returned to its present
bed between Kut el-Amara and Kurna.
(e) In southern Irak, from below Kufeh to the neighbourhood of
Basra, there extended in the Middle Ages a great area of permanent
swamp. The marshes at the north-western end of this area (the
present Bahr-i-Nejef and Bahr-i-Shinafiyeh) had long been in exis
tence, and farther down there had probably always been swamps
which Sumerian, Babylonian, or Greek engineers had not been able
to reclaim. But before the Arab conquest, and since the Sumerians
had begun to build up their civilization here, much of the country
had been brought under cultivation by dyking, drainage, and irriga
tion. The Great Swamp as it existed in the period of the Caliphate
had been formed about the time of the Moslem invasion by the
violent diversion of the Tigris which has been described above.
The Great Swamp contained patches of rich cultivable soil and
maintained valuable fisheries. There was much boat traffic on its
channels.
(/) In the neighbourhood of Basra the waters of the Great Swamp
drained into the Persian Gulf partly by the Shatt el-"Arab, partly
by a channel called the Fayd (estuary) of Basra. The Fayd passed
west of the city and emptied into the Khor "Abdallah. The land
about Basra was irrigated by a number of canals, which took off
from the Shatt el-'Arab and tailed into the Fayd.
Irrigation in Modern Times
After the Mongol invasion in the middle of the thirteenth century
the irrigation-system collapsed. Dykes and dams could not be main
tained at adequate strength, and the waters of the rivers passed
more and more out of human control, spilling where they should
not have spilt, and leaving dry the channels on which cultivation
depended. The great canals silted up and could not be properly
cleared, or were broken by floods or by diversions of the rivers into