'IRAQ AND THE PERSIAN GULF' [‎285r] (572/862)

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IRRIGATION, AGRICULTURE, AND MINOR INDUSTRY 439
Estimated capacity of the lake is 255-3 milliard gallons, enough for
the annual cultivation of over 900,000 acres.
The Kut Barrage across the Tigris at Kut al Imara was commenced
in 1934 and completed, with the complementary regulators, in 1943
(photos. 165, 166). The length of the barrage, of which exact details
are not yet available, is about 2,000 feet, with 56 openings each
about 20 feet wide, controlled by sluice gates, and its height is about
50 feet from base to the top surface, which is crossed by a road.
The Diyala Weir was built in 1927-1928 to replace a temporary
dam of earth and brushwood which used to be built afresh each year
and collapsed under the winter floods when it was most needed. It
is of the ‘standing wave’ type and enables the six Diyala canals to be
fed throughout the year. It was originally intended (in 1923) to
supplement the weir by a barrage higher upstream at the point where
the Diyala enters the Jabal Hamrin, 9,200 feet long and 100 feet high,
thus creating a reservoir lake with a storage capacity of 3,940 milliards
of gallons. This great work would have enabled the cultivation of
1,500,000 acres in the region from the Adhaim southward to Kut.
Uncontrolled Canal Irrigation and Inundation
There are four main zones of uncontrolled canal irrigation depend
ing largely on the use of small channels drawing water directly from
the main rivers. These are:
(1) The Shamiya district between Kifl and Shinafiya through
which run the two branches of the Hindiya channel of the Euphrates
(fig. 8, p. 34). The principal difficulty of irrigation in this rice
growing area is that the land is generally built up by the silt above
flood-levels, and also that the flowing water in the cuts eats away the
alluvial soil upstream, thus creating steps or falls in the channels
(p. 36) which likewise lower the water-levels and prevent inundation.
(2) The lower Euphrates around Samawa and from Nasiriya east
wards to the Hammar lake (figs. 9, 10). Direct use is also made, in
this area, of the spring floods for rice cultivation. This region suf
fered greatly by the dredging of the Haffar channel during the War of
1914-1918, which scoured the Euphrates channel upstream and thus
lowered the water-level below that of the canals (p. 39). In 1927 this
was remedied by closing the Haffar channel with an earthen dam,
thereby forcing the whole of the water into the old off-takes. The
combined acreage of areas (1) and (2) is about 200,000 acres.
(3) The lower Tigris below Kut al Imara, apart from the Amara