‘Persia – especially Seistan’ [‎128v] (255/949)

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be obtained from gauging tbe river is complete, a rough calculation indicates
that the 548 square miles coloured blue in the Gaud-i-Zirreh on the i inch
map would be submerged to a depth of 4 feet by the surplus waters that could
not be used for irrigation in a year like this. Such years of flood come about
every 10 or 12 years. It is probable that the Gaud-i-Zirreh area is very low
and that a deeper and smaller lake would be found at its eastern end, of
capacity sufficient to store such floods. The lands submerged at the north
of the Helmand Hamun, when dry, are, to a large extent, sweet and free from
alkali, indicating, I think, that the water soaks freely through the soil, carry-
ino* the salts with it. But the Gaud-i-Zirreh is described as a brine lake with
much salt incrustations on its margin, due probably to the water drying
up by evaporation, leaving its salts behind. If this is so, the area will not
make so efficient an escape ground for surplus water, as if absorption as well as
evaporation acted to dissipate the water.
9. The broad features of the deltaic valley over which the waters of the
Helmand have at one time or another emptied themselves, are well shown on
the i inch map of the Survey Department, Appendix A. They will be still
more clearly delineated on the i inch surveys now being made by Mr. Tate,
but these are not yet finished. The areas obtained from the inch map as
abstracted in statement A ”, show that the total area of this deltaic valley
is 7,029 square miles, of which 1,318 square miles, or 19 per cent, is watered by
the 5 river as it is at present; 1,534 square miles or 21 per cent is liable to be
submerged; and 3,0 ±1 square miles, or 44 per cent, is land that once was com
manded by the river, but which is now sterile and waterless owing to the
control of the river having been lost; whilst 1,136 square miles, or 16 per cent,
are high plains not likely to be ever irrigable.
At Band-i-Kamal Khan where the river Helmand makes the sudden bend
to the north, the bluffs forming the southern boundary of the river valley end
abruptly, and a clear, well*defined river bed (see Plans Nos. I and II) leaves
the present river valley, and with a bed some 25 feet higher than the present
river hed, goes due west past Tarakun till it eventually breaks up into many
small channels which spread out over a broad deltaic plain terminating at the
southern end of the Hamun just above the off-take of the Shela river. This
old channel is known as the Tarakun Biver, or sometimes the Tarakun canal. Its
bed at Band-i-Kamal Khan is some 25 feet above that of the present river
(Plan No. II). At Kala Afzal, about four miles down the Tarakun channel, a
nulla* goes off to the south-east to the
* Since named John’s nulla. Gaud-i-Zirreh. It keeps close under the
bluffs. Mr. Johns’ section No. I (Plan No. VII) was taken down this old
spill channel of the Helmand, which, as Mr. Johns clearly explains in his note,
gives an admirable line for an escape channel to the Gaud-i-Zirreh. It is the
most eastern boundary of the deltaic plain, which stretches to the w< st and to
the north, and which is bounded on the south by the southern shores of the
Gaud-i-Zirreh and the Shela Kiver ; on the west by the Shela River and the
terrain of the Palan Koh. The area is coloured yellow on tht tracing
(Appendix A). The easternmost end of this plain has been seen by Mr.
Johns, Mr. Tate, and myself, and the western end is crossed by the trade route.
It is all being mapped on the J-inch scale.
It is known to be a rich alluvial plaint
w r ith occasional high plains on it, covered
with ruins of buildings and canals, which
show that it was a highly cultivated,
prosperous tract, which is now waterless and uninhabited, and which could
be restored to prosperity by the construction of a system of canals with a
head at or above Chahar Burjak. Between this alluvial plain, coloured
yellow, and the Helmand River are areasj coloured red, which represent
high plains, some 20 to 40 feet above the
alluvial plain, and which could not be
commanded by flow irrigation, though
some parts of them may be conveniently
irrigated by lift. These plains are composed of clays and loams covered with
a thin coating of gravel, and probably are remnants of the deltaic valley which
t In Afghanistan
In Persia
Square miles.
... 1,426
... 775
2,201
t In Afghanistan
n- ^ #
In Peisia
Square miles.
676
3*7
1,063