'IRAQ AND THE PERSIAN GULF' [‎34v] (73/862)

GEOLOGY AND DESCRIPTION OF THE LAND
Left-bank canals
Right-bank canals
Saqlawiya
27
Yusufiya
27
Latifiya
0-4
Iskandariya .
i-o
Husainiya
3 -o
Hilla .
i 7 ’S
Bani Hasan
3'5
Georgiya (Jarjiya) .
07
25*0
6-5
The canals therefore in 1937 altogether drew approximately 31-5 per
cent, from the Euphrates above the Hindiya barrage in the low-water
season. Lift irrigation to minor canals and direct to fields and gardens
accounted for another 2 per cent, and evaporation was calculated at
about 3-5 per cent. The amount that passed on down the Hindiya
channel was therefore about 63 per cent, of the volume available at
Hit. None of the water drawn off above the barrage in the low-water
season finds its way back to the Euphrates lower down.
The Hindiya Barrage to Samawa (direct distance 115 miles; by Kufa
channel 150 miles)
In Abbasid times almost the whole triangle of country between
Kufa on the Euphrates, Wasit on the Tigris (Shatt al Gharraf), and
Nasiriya was under the waters of the ‘Great Swamp’. Though it is
now impossible to reconstruct the detailed development of the two
rivers, the chief changes in recent times are known from the accounts
of travellers. 1 By the first half of the nineteenth century the eastern
or Hilla branch of the Euphrates was a clear-cut well-graded navigable
channel between Musaiyib (c. 100 ft.) and Samawa (c. 26 ft.), except
through the Lamlun marshes—a remnant of the Great Swamp—
where the channel was narrow, tortuous, and dangerous (fig. 8,
inset A small map or other image enclosed within the margin of a larger map, map sheet, or larger image; or papers placed inside a book or archival volume. A). When the main volume of the Euphrates broke into the
Najaf canal it followed a single course as far as Kill; there the waters
divided into two channels which spilled southwards and formed a
new marsh, the Bahr Najaf, restricted on the west by the desert
escarpment (fig. 8, inset A small map or other image enclosed within the margin of a larger map, map sheet, or larger image; or papers placed inside a book or archival volume. B). This marsh could therefore be drained
back only to the lower level of the old river-bed at Samawa.
Drainage was gradually forced into two or three channels more pro-
mment than the rest, each with a small 15-foot waterfall (naqara) at
its head. These falls rapidly eroded the soft alluvium upstream,
engt ^ in g the drainage channels and gradually restricting the area
of the Bahr Najaf. 6
At the present day the river still divides at Kill into two channels
1 A suggested reconstruction of the development is given in fig. 14 (v, vi).