Innermost Asia : vol.2 / 292 ページ（カラー画像）

0292	Innermost Asia : vol.2
極奥アジア : vol.2

Factors of
geography
affecting
Kuchā.

In view of the extensive archaeological work undertaken by the numerous scholars who had
preceded me in the area of Kuchā, there was but limited scope for further antiquarian investiga-
tion during my own short stay. But I was particularly glad of the opportunity thus afforded of
carrying out surveys likely to throw light on certain geographical factors which must have exercised
a lasting influence all through historical times upon the economic and political fortunes of Kuchā.
The geographical conditions I refer to are of additional interest when they are compared with those
affecting the oasis of Khotan. It will be convenient to review these briefly, so far as they result
directly from the position of Kuchā in relation to the chief physical features of the Tārīm basin,
before I record such detailed observations as I was able to make in the course of my surveys.

Rivers of
Kuchā.

Kuchā owes its comparatively large area of cultivable land, and the ample economic resources
derived from it, to its situation at the point where two considerable rivers, the Muz-art and the
Kuchā-daryā, debouch close together from the T'ien-shan foot-hills into the trough of the Tārīm.
The Muz-art-daryā, by far the greater of the two, is fed mainly from the large glaciers which
descend from the eastern slopes of the ice-clad Khān-tengri massif, the highest in the whole T'ien-
shan system. Before it breaks through the outermost hill range west of Kuchā town in the gorge
below Kizil (Map No. 17. B. 1), it passes through the subsidiary basin of Bai (Map No. 12. C, D. 1),
containing large stretches of fertile soil occupied by flourishing oases. Owing, probably, to the
great amount of sediment which the Muz-art and its several large tributaries deposit here, the
wide fan formed by the river where it issues from the basin is covered by a layer of fertile alluvium
stretching right up to the point of its outflow above Kum-tura.

Abundant
irrigation
facilities.

Just as in the case of the two rivers of Khotan, this favourable circumstance greatly facilitates
the full use of the abundant water-supply for purposes of irrigation ; for where no wide barren
glacis of gravel intervenes between the outflow of the river and the belt of fertile soil, many of the
difficulties of irrigation, such as loss through evaporation, shifting of channels at canal heads, and
similar troubles, are avoided. There is reason to believe that at the present time the irrigation
facilities thus assured to Kuchā are far from being completely utilized. But even so it is worthy
of note that the area of practically continuous cultivation irrigated from the Muz-art-daryā attains
a maximum extent, from west to east, of close on fifty miles, as seen in Map No. 17, while from north
to south, if the Shahyār tract is included, it measures over thirty miles.⁴

Irrigation
from
Kuchā-
daryā.

In the case of the Kuchā river, conditions are somewhat less favourable. It, too, is fed by
glaciers on the main range towards Yulduz, but the volume of water is far smaller. On May 5th,
according to measurements taken by Surveyor Afrāz-gul where the river debouches at Su-bāshi,
it amounted to about 320 cubic feet of water per second. The stretches of bare gravel 'Sai' over
which the canals taking off at Su-bāshi have to be carried reduce the supply actually available
for the cultivated belt of ground east of Kuchā town. The consequent limitation of irrigation
facilities is particularly felt in spring. Fortunately, however, recourse is then possible in this area
to kara-su from springs fed by subterranean drainage, just as it is in the case of Keriya and the
smaller oases east of Khotan. Thus the water of the Kuchā river adds to the arable land of the oasis
a stretch of ground about twenty miles long and six miles wide, which, owing to its position, could
not be reached by irrigation from the Muz-art-daryā.

Positions
of Kuchā
and Khotan
compared.

The importance derived by the oasis of Kuchā from an ample supply of water for irrigation
is much increased by the advantages it draws from its position in relation to two dominant features
in the geography of the Tārīm basin—the mountain rampart of the T'ien-shan rising above it
to the north, and the great desert of drifting sands to the south. We shall readily perceive the

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