‘WAR DIARY. ARMY HEADQUARTERS, INDIA. […] I.E.F. “D”. Volume 14. PART II. (From 16th to 30th September 1915.)’ [‎66r] (136/276)

The figures from January to June are directly supplied by the gauge
records, those for the remaining months have been inferred from the mean river
discharges given by Sir W. Willcocks during each month. The present has
been a year of exceptionally high river flood so that the figures given in the
above table from March to June, at any rate, are in excess of those which would
obtain in a normal year. In a year such as the present one, it can be seen from
the above table that with a supply level of 2'5m. at the barrage, land lying at
21 metres above mean sea level could be commanded at high water of spring
tides from December to June, and at high water neap tides only in May and
perhaps part of April and June. In ordinary } ears the period during which
command could be gained would be less and then only for a short time at high
tide. Winter crops require irrigation from November to May, ordinary summer
crops and inferior rice from April to mid-July and better class rice from April
to September. Water would be required in September and October for gardens
and cotton. It is evident, then, that early waterings for winter crops and late
waterings for summer crops would have to be effected by left irrigation, even in
a year of very high river supplies.
5. Sir W. Willcock’s estimates the cost of the preliminary scheme to irrigate
87,500 acres at L. T. 526,820 or Ds.
Estimated cost and financial aspect. 71,00,000 about, but doubles the figures
to allow for interest charges and subsequent development. The anticipated net
annual returns calculated at L. T. 11 per hectare or about Ds. 6 per com
manded acre of perennially irrigated land amount to 3‘7 per cent, of the
doubled estimated cost. The completed scheme, irrigating 225,000 acres, is
estimated to cost L- T. 998,480 or Rs. 1,35,00,000. Doubling the cost again, the
estimated net annual returns amount to 5 per cent, of the capital outlay (vide
page 52 of Sir W. Willcocks’ report). With the exception of the Nahrwan
project this is the least favourable, of all the Mesopotamian schemes proposed
by Sir W. Willcocks, the estimated returns from which vary 8 8 per cent, to
ITQ per cent, of the doubled figures of estimated cost. All the schemes and
their financial results have been estimated on the same basis but it has been
seen in paragraph 3 supra that the cost of certain embankments and a flood
escape regulator necessary to the scheme were not included in the estimates.
The schemes higher up the delta would provide perennial flow irrigation, while
in the Basrah tract lift must be largely resorted to, and the canal revenue
assessment on the Basrah tract could not in fairness be so high as on tracts
provided with all the year round flow irrigation. Furthermore a fairly large
proportion of the area included in the project is already cultivated in some
measure, so that full water rates could not be assessed on the whole area*.
All these facts tend to render the compari-
pLu-ffS £ son of the Basrah project with the other
eliminated from the top soil by solution and schemes still more unfavourable tO the
deposition on the surface the quality and density former
of the crops will be very poor.
6. The command of the canal system proposed by Sir W. Willcocks could
Suggested improvement of Sir w. Willcocks’ be improved by providing the river creeks
scheme. with sluices. The object of the sluices
would to he retain water in the main channels and irrigants at a high
level, and to render possible scouring velocity at low river levels w 7 hen neces
sary to remove silt deposits. It would not be necessary to provide all the
creeks with these sluices, the smaller ones could be permanently closed by earth
dams and connected to those possessing sluices. To avoid waterlogging, a
drainage system would he necessary, the main drain falling into the north head
of the Kb or Abdulla. The necessity for boat locks to maintain existing
navigation facilities in the creeks could be avoided by building the sluices near
the upper end of the creeks, connecting the existing irrigants to the canal
system and closing off the present intakes from the creeks. By this means
navigation in the existing creeks would not be interfered with at all, but this
plan is not recommended, as by its adoption it would not be possible to improve
the existing irrigation facilities until the barrage system was in operation. It
does not appear to he advisable to embark on the scheme proposed by Sir
W. Willcocks, with or without the modification suggested above, until a real
necessity for it is felt, in view of the better returns that the schemes for the
irrigation of higher parts of the delta promise. It would be more sound to
make a small beginning and work up to a complete and much improved irriga
tion system gradually.
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