1911 Encyclopædia Britannica/Brahmaputra
BRAHMAPUTRA, a great river of India, with a total length of 1800 m. Its main source is in a great glacier-mass of the northernmost chain of the Himalayas, called Kubigangri, about 82° , and receives various tributaries including one formerly regarded as the true source from the pass of Mariam La (15,500 ft.), which separates its basin from the eastern affluents of the Mansarowar lakes, at least 100 m. south-east of those of the Indus. It flows in a south-easterly direction for 170 m., and then adheres closely to a nearly easterly course for 500 m. more, being at the end of that distance in 29° 10′ N. lat. It then bends north-east for 150 m. before finally shaping itself southwards towards the plains of Assam. Roughly speaking, the river may be said so far to run parallel to the main chain of the Himalaya at a distance of 100 m. therefrom. Its early beginnings take their rise amidst a mighty mass of glaciers which cover the northern slopes of the watershed, separating them from the sources of the Gogra on the south; and there is evidence that two of its great southern tributaries, the Shorta Tsanpo (which joins about 150 m. from its source), and the Nyang Chu (the river of Shigatse and Gyantse), are both also of glacial origin. From the north it receives five great tributaries, namely, the Chu Nago, the Chachu Tsanpo and the Charta Tsanpo (all within the first 200 m. of its course), and the Raka Tsanpo and Kyi-chu (or river of Lhasa) below. The Chachu and the Charta are large clear streams, evidently draining from the great central lake district. Both of them measure more than 100 yds. in width at the point of junction, and they are clearly non-glacial. The Raka Tsanpo is a lateral affluent, flowing for 200 m. parallel to the main river course and some 20 to 30 m. north of it, draining the southern slopes of a high snowy range. It is an important feature as affording foothold for the Janglam (the great high road of southern Tibet connecting Ladakh with China), which is denied by the actual valley of the Brahmaputra. The great river itself is known in Tibet by many names, being generally called the Nari Chu, Maghang Tsanpo or Yaro Tsanpo, above Lhasa; the word “tsanpo” (tsang-po) meaning (according to Waddell) the “pure one,” and applying to all great rivers. Fifty miles from its source the river and the Janglam route touch each other, and from that point past Tadum (the first important place on its banks) for another 130 m., the road follows more or less closely the left bank of the river. Then it diverges northwards into the lateral valley of the Raka, until the Raka joins the Brahmaputra below Janglache. The upper reaches are nowhere fordable between Tadum and Lhasa, but there is a ferry at Likche (opposite Tadum on the southern bank), where wooden boats covered with hide effect the necessary connexion between the two banks and ensure the passage of the Nepal trade. From Janglache (13,800 ft.) to Shigatse the river is navigable, the channel being open and wide and the course straight. This is probably the most elevated system of navigation in the world. From Shigatse, which stands near the mouth of the Nyang Chu, to the Kyi-chu, or Lhasa river, there is no direct route, the river being unnavigable below Shigatse. The Janglam takes a circuitous course southwards to Gyantse and the Yamdok Cho before dropping again over the Khambala pass to the ferry at Khamba barje near Chushul. Thence the valley of the Kyi-chu (itself navigable for small boats for about 30 m.) leads to Lhasa northwards. At Chushul there is an iron chain-and-rope suspension bridge over the deepest part of the river, but it does not completely span the river, and it is too insecure for use. The remains of a similar bridge exist at Janglache; but there are no wooden or twig suspension bridges over the Tsanpo. At Tadum the river is about one half as wide again as the Ganges at Hardwar in December, i.e. about 250 to 300 yds. At Shigatse it flows in a wide extended bed with many channels, but contracts again at Chushul, where it is no wider than it is at Janglache, i.e. from 600 to 700 yds. At Chushul (below the Kyi-chu) the discharge of the river is computed to be about 35,000 cub. ft. per second, or seven times that of the Ganges at Hardwar.
For about 250 m. below Kyi-chu to a point about 20 m. below the great southerly bend (in 94° E. long.) the course of the Brahmaputra has been traced by native surveyors. Then it is lost amidst the jungle-covered hills of the wild Mishmi and Abor tribes to the east of Bhutan for another 100 m., until it is again found as the Dihong emerging into the plains of Assam. About the intervening reaches of the river very little is known except that it drops through 7000 ft. of altitude, and that in one place, at least, there exist some very remarkable falls. These are placed in 29° 40′ N. lat., between Kongbu and Pema-Koi. Here the river runs in a narrow precipitous defile along which no path is practicable. The falls can only be approached from below, where a monastery has been erected, the resort of countless pilgrims. Their height is estimated at 70 ft., and by Tibetan report the hills around are enveloped in perpetual mist, and the Sangdong (the “lion's face”), over which the waters rush, is demon-haunted and full of mystic import. Up to comparatively recent years it was matter for controversy whether the Tsanpo formed the upper reaches of the Dihong or of the Irrawaddy. From the north-eastern extremity of Assam where, near Sadya, the Lohit, the Dibong and the Dihong unite to form the wide placid Brahmaputra of the plains—one of the grandest rivers of the world—its south-westerly course to the Bay of Bengal is sufficiently well known. It still retains the proud distinction of being unbridged, and still the River Flotilla Company appoints its steamers at regular intervals to visit all the chief ports on its banks as far as Dibrugarh. Here, however, a new feature has been introduced in the local railway, which extends for some 80 m. to Sadya, with a branch to the Buri Dihing river at the foot of the Patkoi range. The Patkoi border the plains of Upper Assam to the south-east, and across these hills lies the most reasonable probability of railway extension to Burma.
The following are the “lowest level” discharges of the principal affluents of the Brahmaputra in Upper Assam, estimated in cubic feet per second:—
|Lohit river, 9 m. above Sadya ...||38,800|
|Dibong, 1 m. above junction with Dihong .||27,200|
|Dihong ” ” Dibong .||55,400|
The basins of the Dibong and Subansiri are as yet very imperfectly known. That of the Lohit has been fairly well explored. Near Goalpara the discharge of the river in January 1828 was computed to be 140,000 cub. ft., or nearly double that of the Ganges. The length of the river is 700 m. to the Dihong junction, and about 1000 in Tibet and eastern Bhutan, above the Dihong. The Brahmaputra, therefore, exceeds the Ganges in length by about 400 m. The bed of the great river maintains a fairly constant position between its extreme banks, but the channels within that bed are so constantly shifting as to require close supervision on the part of the navigation authorities; so much detritus is carried down as to form a perpetually changing series of obstructions to steamer traffic.
An enormous development of agricultural resources has taken place within the Brahmaputra basin of late years, chiefly in the direction of tea cultivation, as well as in the production of jute and silk. Gold is found in the sands of all its upper tributaries, and coal and petroleum are amongst the chief mineral products which have been brought into economic prominence. During the rains the Brahmaputra floods hundreds of square miles of country, reaching a height of 30 to 40 ft. above its usual level. This supersedes artificial irrigation, and the plains so watered yield abundantly in rice, jute and mustard.