Tarim

Tarim, the principal river of Chinese or Eastern Turkestan, in the middle of Asia. It rises in two head-streams, (I) the Kashgar-darya, which springs as the Kyzyl-su on the N. versant of the Pamir plateau, not far from another Kyzyl-su or the Vakhsh, which flows down the Alai valley to join eventually the Amu-darya, and (2) the Yarkand-darya, which gushes out under the name of the Raskan-darya, on the N. slope of the Karakorum Mountains, just under the Karakorum pass. The former stream flows almost due E. past the city of Kashgar until it joins the Yarkand or Yarkent-darya. The latter, after skirting, in a deep gorge and in a north-western direction, the S. foot of the Sughet Mountains and then of the Raskem Mountains, both constituent members of the western Kuen-lun, forces its way out into the lowlands of Eastern Turkestan and flows N. past the city of Yarkand, then turns N.E. and traverses in a gigantic arc the N.W., N., and E. margins of the vast desert of Takla-makan. Of these two streams Dr Sven Hedin concedes the honour of being the mother river to the Yarkand-darya, on the ground both of its length and of its volume; indeed for some months in the year the Kashgar-darya, mainly owing to the drain made upon it for irrigation purposes after it debouches upon the lowlands, fails to get through to the Yarkand-darya, whereas the Yarkand-darya, on the other hand, never dries up.

The Kashgar-darya enters the Yarkand-darya by a wide delta of anastomosing arms, beginning in the vicinity of Maral-bashi (39° 49' N. and 78° 33' E.). The conjoint river, bearing the name of the Yarkand-darya, flows for some 230 m. N.E. until it encounters the Ak-su-darya from the N. Along this part of its course the river is full of minor sinuosities, with a deep, narrow channel, a sluggish current, and high steep banks, bordered by forests of poplars and thickets of reeds. The Ak-su-darya, which rises at an altitude of 11,000 ft. as the Ak-sai near the S.W. extremity, but on the W. side, of the Kokshal-tau range of the Tian-shan Mountains, soon breaks through that range and proceeds to flow E.N.E. along its southern foot, but under the name of the Taushkan-darya, until it reaches the town of Ak-su in 80° 41' E. and 40° 28' N. Thence it flows S. and S.E. and effects a junction with the Yarkand-darya (Tarim) in about 81° E. The Ak-su, which is swift and brings down large quantities of sediment, infuses new vigour into the main river, giving it an impulse which carries it all the way down to the Kara-koshun.

About 20 m. farther down, the Yumalak-darya or Tarim, as the river then begins to be called, is joined on the right or S. by the Khotan-darya, a stream which rises in the N. ranges of the Kuen-lun Mountains, and fights its way across the all-engulfing sands of the desert of Takla-makan, but with such poor results that it is only about forty days in the year that it makes any contribution to the volume of the Tarim. Some 180 to 190 m. below the confluence of the Ak-su-darya, the river begins to come into direct conflict with the sand-dunes of the great desert, which it has thus far successfully skirted. At the same time it begins to waste its strength in filling marginal or lateral lakes, formed in the hollows between the big sand-dunes (they reach elevations of as much as 300 ft.).

In about 86° 30' E., near the station of Karaul, the river begins to break up in deltaic fashion, and in a long secular process, using Karaul as a sort of pivot, appears to oscillate backwards and forwards like a pendulum from N. to S., and from S. back again to N. between the lake of Kara-koshun (N. M. Przhevalsky's Lop-nor) at the N. foot of the Astin-tagh (see LOP-NOR), and the basin at the S. foot of the Kuruk-tagh (see Gobi), which Baron von Richthofen and Dr Sven Hedin identify with the ancient Lop-nor of the old Chinese geographers. From Karaul down to Ayrilghan or Arghan, a distance of over zoo m., the Tarim skirts the N.E. front of the high sand-dunes of the great desert, spending itself in numerous marginal lakes all the way down, while on the opposite bank (left) it leaves numerous interlacing branches behind it, like the Kunchekish-tarim, Lashin-darya, Yatim-tarim, Ilek, and Tokuz-tarim. None of its marginal lakes is round in shape, but all are elongated, from N. to S. or from N.W. to S.E. This is the general rule, but there is a second series of lakes beside the river which are drawn out from N.E. to S.W. These owe their existence primarily to the action of the wind. Here too, in its delta, the Tarim overflows into more than one chain of a third category of lakes (e.g. Avullukol, Kara-kol, Tayek-kol, and Arka-kol), strung on one or other of its anastomosing deltaic arms. These generally act as regulators and clarifiers, the river emerging from them with crystal-bright water.

Near the head of its delta the Tarim is joined from the N. by the Koncheh-darya, a stream which issues from the lake of Bagrash-kul, its ultimate source being the Khaidu-gol or Khaidyk-gol, which drains the Yulduz valleys of the eastern Tian-shan Mountains. This river, which measures 290 m. from the Bagrash-kul to the Kara-koshun, serves, with the help of the poplar forest which grows along its left bank, as a dam to check the westward movement of the desert sands. Finally the Tarim enters, by a number of arms, the series of shallow, dwindling lakes of Kara-buran, which serve as a sort of lacustrine ante-room to the real terminal basin of the river, the Kara-koshun, which lies a little farther to the E., in 40° N., 89° 30' E., at an altitude of 2675 feet above sea-level. In 1900 -01 Dr Sven Hedin discovered several fresh desert lakes forming to the N. of Kara-koshun, and branches of the deltaic arms of the Tarim, or overflows of such branches, straining out in the same direction, facts which he interpreted as a tendency of the river to revert to its former more northerly terminal basin of the old (Chinese) Lop-nor.

The river not only dwindles vastly between the confluence of the Ak-su (e.g. 16,780 cub. ft. in the second in June) and its embouchure in the Kara-koshun (5650 cub. ft. in the second), but keeps on lifting its bed and its current, like the Po and the Hwang-ho, above the level of the adjacent country. The total fall from the confluence of the Ak-su-darya (3380 ft.) to the Kara-koshun (2675 ft.), a distance of some 665 m., is only 705 ft., giving an average of very little more than a foot per mile. The total length of the river is probably somewhere near moo m. On the whole the Tarim is step by step and year by year steadily but slowly working its way towards the S.W., for all along its lower course it is accompanied by a belt, some 50 m. wide, which lies at a lower level or altitude than itself. In its actual delta this tendency is counterbalanced by its incipient oscillation backwards towards the N., towards the desiccated lake basin of the old Lop-nor. Although the river drains the vast area of 354,000 sq. m., it is only from 172,000 sq. m. of this (48.8 per cent.) that it derives any augmentation of volume. The remaining 182,000 sq. m. (51.2 per cent.) of the potential catchment area fails to contribute one drop of water, being nothing but arid, rainless desert. Throughout the catchmentbasin of the Tarim the precipitation is governed by the general law, that it increases from N. to S. and from E. to W. Hence, in conformity with this, the largest affluents are in the west. In general shape the basin of the Tarim is elliptical, but the lowest part lies near the extreme E. end of the ellipse. "If the deepest part of the basin lay beyond the long axis of the ellipse the symmetry would be ideal; but, situated as it is at the southern foot of the Tian-shan, it has occasioned a dislocation towards the N. of the main stream of the system.. .. If we compare the northern peripheral zone from the catchment area of the Kashgar-darya to the catchment area of the Kuruk-tagh, both inclusive, with the southern peripheral zone from the catchment area of the Yarkand-darya to the catchment area of the Astin-tagh, both again inclusive, we find that the former has an area of 82,990 sq. m., and the latter an area of 89,550 sq. m., or, in other words, that they are approximately of the same size. In the case of both the breadth decreases on the whole towards the E., until they each terminate in a narrow strip, the domain of the Kuruk-tagh on the one hand and that of the Astin-tagh on the other. But before they contract in this way the zones swell out into the Khaidu-gol and the Cherchen-darya and Kara-muran respectively.. A corresponding symmetry can also be seen in the rivers which gather off the encircling mountains into the depression," 1 the Kashgar-darya balancing the Yarkand-darya, the Ak-su-darya balancing the Khotan-darya, the Koncheh-darya balancing the Cherchen-darya, and so on.

The Tarim begins to freeze about the end of November and the freezing advances upwards against the current. When the ice of the river thaws in the beginning of March it sets up a spring flood, which in magnitude and volume falls little short of the flood caused by the melting of the snows on the mountains about the headstreams and feeders of the river, and the course of which can be traced all down the Tarim during the summer and autumn. The river abounds in fish, especially in the lower part of its course. Fish forms the staple food of a large part of the riverine population.

See Sven Hedin, Scientific Results of a Journey in Central Asia,1899-1902(vols. i. and ii., Stockholm, 1905-06), and Central Asia and Tibet (2 vols., London, 1903). (J. T. BE.) 1 Sven Hedin, Scientific Results, ii. 524-25.