"تقرير عن التنمية في بلاد الرافدين مع إشارة خاصة إلى تجديد أنظمة الأنهار" [‎٥] (٥٠/١١)

0
sMfted as the various irrigation systems were used up owing to lack of proper drain
age and scientific grading of the canals. We know that in Egypt there was no
scientific irrigation until after the British occupation, and there is no reason to
suppose that the Babylonians were further advanced than the Egyptians.
(10) There has, however, been a further and progressive deterioration in com
paratively modern times, which can be seen in operation to-day.
The final destruction of the irrigation system by Hulagu took place in 1257 A.D.
and the country came under the rule of the Turks in 1638 A.D. On the disap
pearance of the ancient canals, it became necessary for the remaining inhabitants,
along with such of the invaders who had settled in the country, to construct new
works or die of starvation ; and as the irrigation engineering of the ancients had
become a lost science, there was a reversion to primitive methods. Numerous
channels and ditches were cut opening direct on to the main stream in order to
irrigate a fringe of cultivable land,, and although the volume of water taken by
each channel was in the first instance small, the effect in the aggregate was sufficient
to prevent the river from scouring out the accumulation of silt deposited during
flood time, with the result that there was a corresponding rise in the bed of the
river. Further, the reduction in the volume of water which reached the lower
regions of the river facilitated encroachments on the river bed by cultivators, thus
strangling the river and narrowing its bed. This again had a reactive effect in flood
time, since the river being no longer able to discharge excessive floods was com
pelled to overflow, and thus increased and extended by silt deposits the elevated
area along the banks of the river, which, in turn, acted as an effective bar to the
natural drainage of the country ; and the drainage water unable to work its way
to the river automatically created marshes.
At a later stage, the river being raised above the surrounding country, the
irrigation channels leading from the river to the land beyond the elevated crest
began to scour since they had a steeper gradient than the river itself, and in some
cases—notably, the Chahala, Majar Kabir, and Michiriyah, on the Tigris, and
the Uam Nekhla, Mezlik, and Hakika, on the Euphrates—absorbed the greater
part of the river's flow. Such an escape had the effect of increasing and perpetuat
ing the marshes originally caused by the obstructed drainage, and the accu
mulated water was compelled to find its way back to the river at a lower point in
its bed or to make a fresh channel to the sea.
The result of the whole of the operations has been a further disintegration of
"the rivers and the creation of marshes.
(d) DESCRIPTION OF THE TIGRIS AND EUPHRATES AS THEY APPEAR
T0=DAY.
General Remarks.
(11) The following information is partly from personal knowledge acquired
during my eighteen months' experience of the country, and partly collected from
the available literature on the subject. The total amount of reliable data is
lamentably scant, and emphasizes my remarks in paragraph (1) of this report on
;the necessity for caution until the completion of surveys and studies.
Both rivers have the characteristics of silt-carrying rivers, that is to say—■
the surface of the country through which they flow has been gradually raised by
;Silt deposited when they overflowed their banks ; and as the greatest deposition
has taken place nearest the bank, the rivers flow on ridges with the banks sloping
Cl0i(w)AD " ' ' - ■