The Chandra and the Bhaga rivers are the main drainage lines of Lahaul. After their, confluence at Tandi, their combined waters constitute the Chandrabhaga or the Chenab river. In the Spiti sub-division, major river is Spiti river.The rivers are not associated with any myths or historical events; on the other hand gods-one in each case are supposed to reside at the various junctions of the important streams and all such places are named after these gods. Similarly Places where ancient bridges exist are also supposed to be the abodes of gods; these gods are propitiated by occasional, often annual, sacrifices of goats and sheep
The Chandra river originates from a huge snow, bed on the south-eastern side of the Baralacha la and assumes a large size very soon. During the summer, it becomes unfordable within a short distance, about two kilometers of its source, while the rocky bed, the icy temperature of the water and the swiftness of. the current deter the boldest swimmer. Looking down the valley from the pass, a vista of grand peaks and glaciers, on the right hand side, falling abruptly to the water’s edge makes a memorable impression on the visitor. On the left hand, the slopes are bare the feet of which remain perpetually covered under heavy mass of debris falling from above.Lower down, the Chandra Tal, a kilometre long and a half wide, lies in a broad grassy plain, the lake is placed between a low ridge and the main Kunzam Range with an outlet into the river. Following a general south-westerly course for about 48 km the river sweeps round to the west whence a further course of 64 km west and north-west takes it to Tandi where it meets the Bhaga river. Throughout its course the river is fed by a number of glaciers the biggest being the Shigri on its left bank, and the Samundari on the right. The chief tributaries of the Chandra below Shigri lie on the right bank and they originate from the Sonapani glacier opposite Khoksar and the Sissu glacier. The left bank is steep and bare, but there is good grazing ground on the right bank beyond Khoksar. There are several villages on the right bank as far as Sissue, and from Sissue the valley becomes richer and cultivable down to Gondhla. The hamlets grow larger as Gondhla is approached, and the houses are seen to be better built, surrounded by groves of poplar and willow. The northern mountains take gentler slope, but on the south, opposite Gondhla, the whole mountain side, from the peaks over 6,090 metres to the river bed below. 3050 metres, is visible. Glaciers and snowfields overhanging rocky steeps merge into grassy slopes below. At one point the cliffs descend for some 1,210 metres and form the grandest precipices in the world.
From its source to its confluence with the Bhaga at Tandi, the Chandra registers a fall of about 12.5 metres per kilometre.
The Bhaga river rises in the Suraj Tal or Lake of the Sun, a name given to the small but deep tarn situated well on the summit of the Baralacha Pass, a little below an altitude of 16,000 feet. The Bhaga is another significant constituent of the Chenab river system. It takes its origin from the snow-bed on the south-western foot of the Baralacha Pass and flows northwest and later curves round to the south-west. The country is barren down to Darcha village, which is situated near the junction of the Yoche Nullah and the Zangskar Chu with the main stream at about 3,500 metres from the sea. The total length of the river is about 65 km with an average fall ofabout 28 metres per kilometre. The banks of the stream are steep and rocky.
Below the confluence of the Chandra and the Bhaga at Tandi the joint stream is known as Chandrabhaga. From a height of about 2800 metres the fall of the river is six metres per kilometre through 25 km of length in a north-westerly direction to the border of Chamba district. The side ravines are numerous the biggest among them being the Chokhang nullah, which pours in from the north by the village of Thirot.
In its upper course through Lahaul valley, the river Chenab is known as the Chandra-Bhaga. It is formed by the rivers Chandra and Bhaga and hence the name. As it flows through Lahul, this river has laid thick deposits of sediments. It is in spate during the summer season when the snow on the mountains melts. Flash floods occur with regularity in the early afternoon in summer. They have been known to wash away hundreds of cattle each year. The river Chandra-Bhaga may freeze occasionally during the winter season.or Chenab River
The Spiti river has its source far north on the eastern slopes off mountain ranges which ruin between Lahul and Spiti. The river is formed at the base of the Kunzam Range by the confluence of Kunzam La Togpo and the streams Kabzima and Pinglung. On the western side of its sour lies a vast salt-water lake. The river follows a long winding course interloced here and there by spurs that project from the foot of the plateaus on both sides. The Spiti has a broad and flat valley bordered by high vertical cliffs. The valley tops are flat and plateau-like. Above the ’plateaus and land again rises in steep scarps. The length of the river within Spiti on the south-east, is about 130 km. It continues in Kinnaur district upto a place known as Khabo where it joins the Satluj.
The main stream of the Spiti river, which is fed by the glaciers, is a perennial one, while some of the tributary streams disappear in the loose morain at the feet of the plateaus. During its course through the difficult, complex terrain, the Spiti is joined by a number of tributaries from both the sides. Those which join its right bank include: Chiomo, Gyundi, Rahtang, Ulah, Pin, Lungze, Mane, Surahl, Pomograng, Mamdang and Sumra; the left bank tributaries are: Thamar, Hanse, Thumna, Tagting, Thumpa Lumpa, Shila, Kaza, Lingti, Poh, Tabo, Karati, Gimdo and Parechu.
The Pin river constitutes the most important right bank tributary of Spiti river. Its main branch, Kyoti, originates from the Lasuma mountain in the Srikand Range of the Middle Himalayas. It is joined by another branch from the Bhaba Pass near Mudd village. Later it is fed by a number of streamlets, chief among which are Palder Chin, polder Chum and Shang on the right bank, and Karve, Lavrang, Mudd Taking, Madang, Saguaro, Barakuit, Gooling, Seeling and Kit ’togpos’ on the left bank. The Pin is about 50 km long. The Gyundi and the Rahtang, like the Pin, rise from the Mid-Himalayas and are fed by glaciers.
Of the left bank tributaries of the Spiti, the most important are: Lingti, Gimdo and the Parechu, all of which rise in the main Himalayas. Lingti is about 40 km in length and there are a number of villages in its watershed. Parechu, which starts from near the Tagling La and Parang La ranges, runs north-east and joins the Spiti at Sumdo.
The Spiti rivers are all violent torrents whose depths vary enormously, depending upon the season. In winter, when the water freezes, the Spiti is barely about half a metre deep and at its widest only a stone’s throw across, and has a discharge of a couple of hundred cusecs. Its water, heavily charged with silt, is generally turbid and yellow. Fording, especially in the latter part of the day, is thus rendered perilous and almost impossible. The maximum discharge in the river, at the point where it enters Kinnaur, may go as high as twenty to thirty thousand cusecs. The discharges in its tributaries also are subject to seasonal, daily, and even hourly fluctuations. None of the rivers is navigable. The larger tributaries of the Spiti flow through valleys which sometimes resemble its own. But shortly before joining it, these are forced into narrow chasms in the rocky heights which rise on either side of the main river. The depth of these cuttings is enormous; the walls of the canyon in the Shila Togpo can hardly be less than 600 metres. The Pin gorge is several kilometres in length; similar rocky chasms can be seen in the gorges formed by the Sampa, Lingti, Rahtang and Gyundi togpo.
In the north, the Tsarab runs north-westwards for about fifty kilo-metres before joining the Lingti river and entering Zangskar in Ladakh. The Tsarab is, because of its peculiar location, not used for any purpose by the Spitians. Its watershed does not contain any human habitation; it ultimately joins the Indus in Ladakh.
Bara Shigri Glacier<
The largest glacier in the district is situated in Lahaul sub-division known as Bara Shigri, Bara meaning big andShigri meaning glacier, in Lahaul dialect. Many mountaineers have trekked it for the sake of hobby orgeographical exploration. This glacier rises from a number of large glaciers, meeting in great valley above, filling that up, and then pushing themselves over its rim in one great ice-stream down to the river.
Hugh Whistler, writing in 1924, says, “Shigri is applied par-excellence to one particular glacier that emerges from the mountains on the left bank of the Chandra. It is said to be several miles long, and the snout reaches right down to the river, lying athwart the customary road from Kullu to Spiti.” Estimates differ as to the breadth of the glacier where it is crossed, as owing to its movement and roughness no two caravans cross it in exactly the same way, but it is not less than a mile wide. In 1836 this glacier burst its bounds and dammed the Chandra, causing the formation of a large lake, which finally broke loose and carried devastation down the valley. The story runs that the people of Spiti posted guards in the Kunzam Pass to watch whether the water would rise high enough to flow across into Spiti.”
The Bara Shigri glacier attracted much attention for many years because of the valuable antimony deposits found there. The glacier was first surveyed in 1906 by H. Walker and E.H. Pascoe of the Geologiaal Survey of India. Daring 1955 the Geological Survey of India sponsored an expedition to this glacier as part of the Indian programme for the International Geophysical Year 1956-57, when a number of Himalayan glaciers were examined and their snout position fixed.
The Bara Shigri glacier, whose name signifies ’boulder-covered-ice’, flows northwards and debouches into the Chandra river where its southerly course is deflected westwards, close to the Spiti border. The glacier is above 3,950 m altitude and extends beyond 4,570 m, a 11 km length of which has been recently surveyed and mapped. The glacier is so heavily covered with surface moraine that ice is not visible for long stretches except along the crevices and in the ablation areas.
Across the Bara Shigri is another glacier known as Chhota Shigri. It is a comparatively smaller glacier and does not reach down to the bed of the river, but it is most steep and slippery, difficult to cross.
The Gangstang glacier situated at the western border of the Lahaul region at an altitude of about 5,480 m streaming into Shahsha nullah which joins the Chandrabhaga river at about 13 km to the south.
The desiccated glacier lake and the old terminal moraine are visible from the Rohtang Pass. The desiccated lake, about 2.5 km in length, is a narrow meandering plain following the contours of bounding slopes and consists of such fluvio-glacial deposits as mud, fine sand, pebbles and angular gravels, through which the glacier stream runs. The glacier is about 11 km long. An ice-cliff forms the snout which is mostly covered by stone, and the stream issues from an ice cave situated towards the western limb of the curved ice-cliff. To the south of the snout, and near to it, is a small terminal moraine. A large terminal moraine used to hold up the waters of the old lake. Three more old terminal moraines are cut through by the Sonapani stream after its escape from the lake-bed.
It is a small one and is easily accessible being within one kilometre of Putiruni. There is a well marked ice-cave and the glacier stream runs between two large lateral moraines.