"كتيّب بلاد الرافدين. المجلد I. ١٩١٨" [‎١‎٧‎٥] (٥٦٨/١٨٤)

AGrRICULTUEE AND LAND TENURE 175
means of irrigation in Irak are water-lifts oil-pumps,
canals, and dams (on these see further p. 160). Along the river-
channels the ground slopes downwards away from the banks.
Distributing canals descend these slopes and in many instances tail
into marshes. The higher part of the slope, nearest the main
channel, being the driest is most likely to be suited for the cultiva
tion of barley and wheat. The lower slopes, being more easily
watered, may be used for rice-fields. Millet may be raised on
intermediate levels between the winter crops and the rice. Changes
in the location or the character of cultivation may be caused from
time to time by changes in the distribution of the water-supply.
Land that at one time produced rice may now, owing to a drop in
the water-levels, yield only wheat and barley, or vice versa; or
cultivation may have to be given up altogether, the water that
formerly supplied the land being diverted elsewhere. The dispro
portion between the area of cultivable soil and the area actually
cultivated makes it easy to break new ground. It is said that the
policy of the Dairat es-Sanlyeh was to. acquire the most easily
worked canals and to push each as far as it would go, never irrigating
the same land a second time until the canal had been carried to its
greatest possible length. The Arab cultivator is wasteful in the use
of water, and his crude methods of obtaining it are partly responsible
for the present disiutegration of the rivers. (See p. 154.)
In upper Mesopotamia irrigation is employed chiefly in the
cultivation of rice, cotton, maize, millet, and fruits. In parts of
the middle Tigris and middle Euphrates valleys water is lifted by
cherrads (see p. 160). Where the water has to be raised to a consider
able height naurs are used. These are large water-wheels, built out
into a stream on dams and lifting the water by means of buckets. 1
It is said that in the Mosul neighbourhood water-wheels are some
times placed in wells. The damming of streams for irrigation is
a common practice ; the water held up by the dam is either allowed
to flood the neighbouring fields or diverted, into runnels [karezes).
In some parts of the country, and notably in the Erbil—Kirkuk
region, such runnels may be carried underground {qanats, sometimes
also called harezes).
Canal irrigation is used in Arabistan. In the Eellahlyeh district
there is an elaborate canal system supplied by the waters of the
Jerrahi. In the northern province underground channels are found.
On the Karim irrigation was formerly maintained by means of great
dams at Shushtar and Ahwaz (see p. 156, foot-note).
1 Similar wheels are used to drive flour-mills.