'Report on the Development of Mesopotamia with Special Reference to the Regeneration of the River Systems' [‎7] (13/50)

Discharge of Effluents.
Name of Effluent.
Flood cusecs.
Low-water cusecs.
Chahala Canal
14,424
4,503
Majar Kabir Canal
7,818
Abu Tabar
862
Michiriyah Canal ..
4,296
1,500
TV illcocks's book and the remainder from my own observations. In high-flood the
figures are all probably greatly exceeded for short periods.
(14) Sir William Willcocks estimates the high-flood discharge of the Chahala
at 35,000 cusecs and the Majar Kabir at 21,000 cnsecs. Assuming his figures to be
reasonably correct, conditions must have greatly altered since 1908, as I believe my
discharges to be as nearly accurate as possible and 15,000 to 16,000 cusecs to be the
maximum flow down the Chahala and 8,000 cusecs for the Majar Kabir.
Accompanying this note are a sheet of cross-sections of the river from Baghdad
to Basra, some photographs of the river between these points, and a survey sheet
from Amara to Kurnah ; a study of these drawings and photographs, with the
discharge tables, is very illuminating and clearly indicates the disintegration of the
river through human abuse and neglect described in paragraphs 9 and 10 supra.
(15) A river under ordinary conditions increases in width as it reaches its
mouth, but the Tigris at Baghdad is a fine stretch of water, and at Qualat Saleh
a ditch.
Between Amara and Aziziah no less than 81 canals, exclusive of the Hai,
take off from the right bank ; but the bulk of them are dry at low-water, which
accounts for the low-water discharge at Baghdad and Amara being practically
the same, whereas the flood discharge lit Amara is only one-third of the discharge
at Baghdad.
(16) The real menace to the existence of the Tigris as a river takes place, how
ever, between Amara and Ezra's Tomb where large canals carry away the greater
part of the low-water discharge. The principal offenders are the Chahala, Majar
Kabir, and Michiriyah canals.
The Chahala, sometimes known as the Hud, was opened out as a small irrigation
ditch about 100 years ago. It now takes nearly half the low-water discharge of the
Tigris above Amara, and, after irrigating in an extravagant manner the country
through which it and its many branches pass, loses itself in the swamps.
The Majar Kabir and the Michiriyah are equally wasteful of water, and the
gravity of the situation has been greatly increased by the Arabs having been allowed
to reclaim large areas of land on both banks of the Tigris between Qualat Saleh
and Ezra's Tomb, thus still further reducing the sectional area of the river which
now, in time of floods, spreads over the Whole of the surrounding country like a sea.
In the neighbourhood of Ezra's Tomb the water from the swamps begins to
return into the river from both sides, and at Kurnah the low-water discharge is
practically the same as at Amara and Baghdad.
Slope of river.
(17) The following table gives the slope of the water in flood and at
low-water between Kassar Hassan Bey, 177 miles above Baghdad, and the sea.