'Handbook of Mesopotamia. Vol. I. 1918' [‎281] (290/568)

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COMMUNICATIONS AND TRANSPORT 281
Ezra's Tomb and Qal'at Salih, where in places it is only 66-75 yds.
Current about m.p.h. in low water; in flood-times it may be
6 m.p.h. or more, and averages about 4 m.p.h.
The greatest difficulties are to be found : (1) in the reaches above
mentioned from Ezra's Tomb up to Qalat Salih, where, owing to
the great volume of water spilt from the river-bed down large canals
above Qal'at Salih, the channel narrows and shallows; moreover
the bends here are very frequent and sharp; (2) at places between
Kut el-Amara and Baghdad, where there are banks of silt which
give much trouble in low water.
Besides the seasonal variations in the state of the river, changes
are constantly taking place which more or less alter the details of
navigation from year to year. When the river is falling in the
summer the channels take some time to form and are often very
erratic.
The improvement of the waterway of the Tigris has been under
consideration, and certain measures have already been taken:
(i) Kurna—Amara.
Some work has already been done to improve conditions in the
narrows between Ezra's Tomb and Qalat Salih.
The measures that have been recommended include the following :
(1) Restriction of the amount of water taken off by the larger
canals, so far as may be consistent with the needs of agriculture;
closure of unimportant and useless channels.
In 1916 a weir was built at the head of the Michriyeh canal,
where the loss of water from the main channel was then most
serious. Later it was found that there was serious danger from the
increasing spill of water down the Jehaleh (Chahala) canal at Amara.
A bar which had previously acted as a weir at the head of this
canal had disappeared, and more and more water was here escaping
from the river-bed. In the spring of 1917 measures to check this
process were under consideration.
(2) Dredging of narrowest parts of the navigation channel.
(3) Conservancy regulations, to prevent the Arabs of the neigh
bourhood from cutting canals at the river-bends, and from reclaiming
land on the river-bank by means of brushwood groynes.
(4) Construction of retired bunds or levees in order to provide for
the ultimate flow of the bulk of the river's flood-waters down the
regenerated channel.
The digging of new cuts across the bends would not be safe
unless a careful survey had made it possible to foretell what would
be the effect on the river downstream.