The Himalayan drainage mainly consists of three river systems: (1) the Indus System, (2) the Ganga System, and (3) the Brahmaputra System.
1. The Indus System
The Indus (Sindhu) is the westernmost of the Himalayan Rivers which originates from a glacier near Bokhar Chu (31° 15′ N and 81° 40′ E) in the Tibetan region (altitude 4164 m) east of Mt. Kailas (6714 m). At first it flows north-west in the trans- Himalayan region (called Singi Khamban or lion’s mouth in Tibet and cuts across the Ladakh Range forming a spectacular gorge (depth 5000 m) near Gilgit in Jammu and Kashmir.
It is one of the largest river systems of the world with total channel length of 2,880 km (in India 709 km) and a catchment area of 1,165,000 sq. km (in India 321,290 sq. km). India can utilise only 4,195 million cubic metres (only 20%) out of its total discharge under the Indus Water Treaty. The Indus isjoined by its Himalayan tributaries like Gartang, Zaskar, Dras, Shyok, Shigar, Nubra, Gilgit and Hunza in Jammu and Kashmir. Near Attock it receives the Kabul River and its tributaries. Some of the important tributaries south of Attock include the Kurram, Toch and the Zhob-Gomal.
The collective flow of its well known Punjab tributaries-Satluj, Beas, Ravi, Chenab and Jhelum-go to make the Panjnad which falls into the mainstream a little above Mithankot. The river flows south- westward across Pakistan to merge into the Arabian Sea east of Karachi.
The Jhelum rises from Seshnag and flowing through the Wular Lake it makes a deep gorge at Basmangal (2130 m) near Pakistan border and finally joins the Chenab atTrimmu. Of its total catchment area 28,490 sq. km. lie in India (average annual discharge at Mangla is 2,789 crore m-1). The Chenab (Asikni or Chandrabhaga) rises near Baralacha Pass in Lahaul and after flowing in north-westerly direction takes a knee-bend at Kishtwar.
It flows for 1,180 km in India draining over 26,755 sq. km of area in India before entering Pakistan. Its annual flow at is about 2,900 crore m3. The Ravi (Parushni or Iravati) emerges from the mountains of the Bangahal basin in Himachal Pradesh.
It flows for 725 km and drains 5,957 sq. km of area in India before entering Pakistan and joining the Chenab near Sarai Sidhu. At Madhopur its annual discharge is about 8,000 m3. The Beas (Vipasa or Argikiya) rises on the southern face of the Rohtang Pass in Kullu (4,000 m). It forms gorges at Koti and Larji. Its total course of 470 km and drainage area of 25,900 km2 lie in India. The river carries about 15,800 m of water annually at Mandi.
The Satluj (Satadru or Satudri) rises near the Manasarovar Lake at a height of4, 630 m. It is called Langchen Khambab in Tibet and is an antecedent river. It flows parallel to the Indus for 400 km before entering India and carves out a deep gorge at Rupar. In India the length of its course is 1,050 km draining an area of 24,087 km2. Its annual flow at Rupar is about 1,660 crore m. The river supports the Bhakra- Nangal multipurpose project and the Harike and Sirhind systems.
Under the Indus Water Treaty signed by India and Pakistan in 1960 India has got the exclusive right of utilising the waters of three eastern most rivers (Satluj, Beas and Ravi) of the Indus system and Pakistan for the remaining three western rivers (after meeting the needs of the Jammu and Kashmir state). Accordingly old canals are being linked with these rivers and new irrigation and power projects are being installed.