'Seistan. Irrigation report of the Perso-Afghan Arbitration Commission, 1902-1905. Volume I. Report and appendices. Simla: Government of India Foreign Department, 1906' [‎98v] (201/500)

84
[Chap. XIII,
But this scheme could only be undertaken if it were certain that the Gaud-i.
Zireh could safely hold all the water of a great flood. A correct knowledge 0 {
the rate of evaporation on the Gaud-i-Zireh is most important, if this rate were
10 feet a year, there would be no danger in passing all the surplus water to the
Gaud-i-Zireh ; but if the rate is only five feet a year, there is danger of the Gaud-
i-Zireh overflowing in large volume into the northern basin and wrecking the
reclamation embankments and destroying the cultivation •
All the information about the rate of evaporation has been fully discussed
in Chapter VI and the problem of draining the inundated area will be fully
described in the fifteenth Chapter; it is only necessary here to emphasise the very
great importance of obtaining an accurate knowledge of the rate of evaporation
off the inundated area; this information is as essential as that of the volume of
water poured in by all the rivers.
The first point to be decided under this scheme will be the abolition or
retention of the Naizar discussed towards
Abolition or retention of the Naizar. t he end of Chapter XV. It will be po S .
sible to control the flood waters so as to keep an area^in the Naizar under reeds: it
will also be possible to drain and reclaim the Naizar. It is probable that either
system will be equally feasible under this scheme and that there will not be much
difference of cost. If the Naizar is maintained, a large part of the flood volume of
the Helmand must be conveyed to the Northern Hamun ; the Naizar cannot be
maintained from the flood waters of the Kh£sh, Far&h and Harud, as they are too
uncertain in their volume, and are not likely to be brought under control at the
same time as works are undertaken for that purpose on the Helmand.
We may now consider the works required under the first scheme. It has
r . ,, „ , been said in the footnote of the first paee
Works required for firs, scheme. of ^ ^ ^ J ^
weir on the present river would be across the river opposite Deh Ghulam Haidar;
the ford of Bandar*i-Kamal Khan and the ruins of Kala-i-Kamal Khan are
situated above the entrance of the Rud-i-Taraku trough, while the Gumbad-i*
Nadiri on the left bank of the river opposite Deh Ghulam Haidar marks the
down-stream entrance of the trough. The river-bed from Kala-i-Mir, one mile
above Guzar-i-Bandar-i-Kamdl Khan to Guzar-i-Gumbad, 4 miles below the ford
and nearly 2 miles below Deh Ghulam Haidar, has a very low gradient, the fall
being only 4-J feet in the 5 miles. The material of the bed is uniform through*
out this reach and is shingle with small boulders.
The works required to gain control of the river and to send the surplus
waters partly to the Northern Hamun and partly to the Gaud-i-Zireh would be
as follows
(i) At Deh Ghulam Haidar a regulating weir with gates across the
present river ; perhaps a regulator across the head of the Tarakd
Channel to keep control of that also.
(ii) At Kala-i-Afzal a weir over which to control the escapage to the
Gaud-i-Zireh, and a regulator at the head of the canal to the
delta formerly watered by the Rud-i-Taraku. Scouring sluices
will be required on the weir in front of the canal head.
(iii) Weirs and regulators would also be required at the point in the
northern delta where the branch of the river coming from Deh
Ghulam Haidar ended, and the water was distributed by escapes to
the basins and by canals to the land. As has already been pointed
out on page 77 tb e test Chapter, this point would be somewhere
between Dam-i-Kalan and Kala-i-Gawak. All the above weirs
and regulators would be like those on rivers and canals of similar
size in Northern India.
(iv) From the weir at Deh Ghulam Haidar to the weir and regulators
near Dam-i-Kalan for distributing the waters over the northern
e ta the channel of the present main stream would suffice with*
out any works as Jar as can now be foreseen. But some excava
tion will be required on the channel from Deh Ghulam Haidar to
areas Jould bYdifferentlate? ^omsafe^'n^hlbiutiois and Th S be flo ° ded at Such timeS ’ aS ^Mhe
floods. naoitations and other valuable properties placed out of the reach of