'Handbook of Mesopotamia. Vol. I. 1918' [‎153] (162/568)

* CHAPTER X
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IREIGATION OF IEAK
Introduction—Irrigation of Irak under the Sassanids and Caliphs—Irrigation
in modern times—Sir William Willcocks' scheme.
Introduction
The rainfall, which is practically restricted to the months
November - May, is too slight for the needs of the country (for
details of rainfall see Chapter II). It is indeed not without some
importance for agriculture. ' During the winter months, as a general
rule, the rainfall is a not inconsiderable factor in the success of the
crops; and over large areas of Mesopotamia barley is sown and
matured in sole dependence on the winter rainfall.' But even in
its present under-populated and under-cultivated condition Irak
depends on irrigation for by far the larger proportion of the crops
raised in it.
Perennial irrigation is needed in Irak, and one of the main problems
of irrigation is how to maintain a sufficient supply of water when
the rivers are low. The flood season, falling in spring, is rather
' too late for the winter, too early for the summer crops(On the
rise and fall of the rivers see pp. 24-5.)
The general lines of any irrigation-system in Irak must be in
part determined by the following relations of its surface levels ;
r ^ a \ The Euphrates from Fellujeh to Diwanlyeh is higher than the
Tigris between Baghdad and Kut el-Amara, and commands the
country between the two rivers. (Ground-levels on the Euphrates :
at Fellujeh, 130 ft. above sea-level; at Divvaniyeh. 85 ft. ; on the
Tigris: at Baghdad, 105 ft.; at Kut, 79 ft.)
(£0 From the left bank of the Euphrates between Fellujeh and
Diwanlyeh, and from the right bank of the Tigris between Baghdad
and Kut, the ground falls away very gradually, the slopes from the
two rivers forming a depression, the lowest line of which, starting
from the southern end of Lake 'Aqarquf, runs at a distance of
4-18 miles from the Tigris to a point about W. of Bogheileh.
Thence its course bears more to the south, and it is continued by