'Handbook of Mesopotamia. Vol. I. 1918' [‎156] (165/568)

156
IRKIGATION OF IRAK
a long time to come the Arabs of Irak will not be able to take
advantage of more than a gradual extension of the irrigated area by-
means of local works.
On the other hand it would appear dangerous to execute schemes
for local irrigation which were not based on a careful and compre
hensive study of the rivers and of the needs, present and future, of
the country as a whole. Local works not planned on the basis of
such a study might compromise the interests of other parts of Irak,
and even in the end do more harm than good to the district which
they were meant to benefit.
Irrigation of Irak under the Sassanids and Caliphs
The irrigation of Irak seems to have reached its highest point
of development under the Sassanids (third, fourth, fifth, and sixth
centuries a.d .). 1 Most of the great canal-beds which still exist in
various stages of disrepair seem to have been either wholly or in
great part the work of the Sassanian Government. Under the Arab
Caliphate systematic irrigation was at first fairly well maintained,
but with the weakening of the central Government it fell gradually
into decay, and it was finally wrecked in the havoc caused by the
Mongol invasions of the thirteenth century.
(a) On the left bank of the Tigris the country from Samarra down
to Kut was irrigated by the Nahrawan canal and its branches. The
1 It may be noticed that the Sassanids also carried out great irrigation works
in Arabistan. The Sassanian Government seems to have been mainly responsible
for the dams on the Kama at Shushtar and Ahwaz.
The works at Shushtar have undergone considerable modifications and
repairs at different times. There are three great dams here :
(i) On the Shatait branch of the Karun a combined bridge and dam known
as the Band-i-Mizan or Pul-i-Kaisar. This work, now broken, held up water
for the Miyanab canal which waters the Miyanab island between the Gargar
and the Shatait branches of the river.
(ii) At the head of the Gargar branch a dyke, with a crest about low-water
level and six sluices, called the Band-i-Kaisar or Band-i-Shahzadeh.
(iii) Half a mile below the Band-i-Kaisar a dam called the Pul-i-Bulaiti
rising to above high-water level.
The Ab-i-Gargar was apparently cut or enlarged in the Sassanian period.
Tradition connects these works with the Koman Emperor Valerian, who was
taken prisoner by the Sassanid King Shapur about a. d . 260. It is possible that
Roman engineers were employed in their construction.
At Ahwaz may be seen the remains of a massive Sassanian weir along the
line of one of the shelves of rocks which form the rapids. This weir held up
water for canals which are still traceable, and it has been lately proposed to
rebuild it.