Maps usually show geopolitical boundaries: countries and provinces. A more meaningful view of the mountains is as per its natural boundaries defined by the flow of water. Snow covered high ranges are drained by major river valleys into the plains. The catchment area of a river is defined by the boundaries of its basin. A mountain range is composed of multiple basins formed by seasonal drainage of rainfall, winter snow and glacial melt. Ridgelines (water divides) which are the natural boundaries of the basins sometimes also coincide with geo-political boundaries although in many cases not. Understanding a mountain range through its basins gives you the best understanding of its geography. The Western Himalayas is made up of 12 major basins, each drained by a network of major streams (Northwest to Southeast):
- Shyok
- Indus
- Spiti
- Jhelum
- Chenab
- Ravi
- Beas
- Sutlej
- Yamuna
- Bhagirathi
- Alaknanda
- Sharda
Basins below are generated through QGIS. Check this post on how to create your own,
Shyok basin
The Shyok river drains the Karakoram in the North and Ladakh range in the South. Major tributaries are the Tangse (Pangong Tso) and Chang Chenmo rivers both originating in China and the Nuba. The Shyok flows South turning West into Pakistan where it eventually merges with the Indus. The Shyok basin is bound by Indus (South), China (East) and Pakistan (West).
Indus basin
The Indus flows for a good distance in Tibet, China before in enters East Ladakh flowing Northwest into Pakistan where it merges with the Shyok. Major tributary is the Zanskar river which drains most of Zanskar through its own tributaries: Tsarap Chu, Markha, Khurna, Zara Chu, Khargyak, Stod Dada. The Dras and Suri rivers join the Indus before it flows into Pakistan. Major towns in the Indus basin are Leh, Padum, Kargil and Sarchu. The Indus basin is bound by Shyok (North), Chenab (South) and Spiti (East).
Spiti basin
The Spiti basin is bound by Lahaul (West), Ladakh (Northwest), China (Northeast) and Pin Valley National Park (West). It consists of two major rivers: the Spiti originating in the West and the Pare Chu (Tso Moriri) in the North which enters nd exits China. The Spiti and Pare Chu merge between Tabo and Nako and eventually flow into the Sutlej river which originates from Tibet. Pin and Lingti rivers are major tributaries of the Spiti. Major towns are Kaza, Tabo, Nako, Mud, Karzok. The Spiti basin is bound by the Indus (North), Chenab (West) and Sutlej (South).
Jhelum basin
The Jhelum basin is drained by the Neelum in Pakistan and Jhelum in Kashmir. Jhelum river drains the Great Himalayan Range (East) and Pir Panjal (West) into the Kashmir valley merging with the Neelum in Pakistan. Major tributaries are the Sind, Lidder, Pohru. The Jhelum basin is bound by the Chenab basin East and South.
Chenab basin
The Chenab river drains the Great Himalayan Range (Northeast) and Pir Panjal (South) into Jammu. The Chenab basin is bound by Ladakh (East), Chamba (South) and Kashmir (North). It originates from the Chandra and Bhaga rivers joining in Tandi to become the Chandrabhaga or Chenab river. Major tributaries are the Miyar, Bhut Nal, Warwam, Ans and Tawi. The Chenab river originates in Lahaul flowing through Pangi valley into Jammu. Chenab basin is bound by Jhelum (North), Ravi (South), Indus (East).
Ravi basin
The Ravi river drains the Pir Panjal (North) and Dhauladar (South) through the Chamba valley flowing West and joining the Beas river in the Punjab plains. The Ravi basin defines the Chamba valley bound by Chenab (North), Beas (East, South). The Ravi river originates from the Ravi near Bara Bhanghal and the Bhudil Nal near Kunti. Major tributaries are Tandan, Baira, Sewa. The Ravi basin is bound by Lahaul
Beas basin
The Beas river drains the Pir Panjal (North), Dhauladhar (West), InderKilla, Keerganga and GHN0 (East) through the Kullu valley. Major tributaries are Parvathi, Saini, Tirthan and Uhl rivers. The Beas basin is bound by Chenab (North), Sutlej (East), Ravi (West). Beas basin is located in Kullu district bound by Lahaul (North), Kinnaur (East), Kangra (West). Major towns: Kullu, Manali, Kasol, Banjar, Barot, Mandi.
Sutlej basin
The Sutlej river originates from Tibet flowing West through Kinnaur joining Beas in the Punjab plains. Sutlej basin is bound by Spiti (Northeast), Yamuna (South, East), Beas (North). Major tributaries: Spiti, Basra, Ropa, Taiti Garang. The Sutlej basin is bound by Spiti and Kullu (North), Uttarkashi and Shimla (South). Major towns; Reckong Peo, Sangla, Rampur.
Yamuna basin
The Yamuna basin drains the Bandarpunch in the Northeast and is bound by Kinnaur and Shimla (North) and Uttarkashi (East). Major tributaries are Tons, Pabar, Giri and Aglad. Major towns are Yamunotri, Chirgaon, Barkot, Sankri, Shimla, Sainj, Rajgarh, Mussoorie and Dehradun.The Yamuna basin is bound by Sutlej (North) and Bhagirathi (Southeast).
Bhagirathi basin
Bhagirathi river drains the Bandarpunch (North) and Gangotri (East) bound by the Yamuna (West) and Alaknanda (East). Major tributaries are the Jadh Ganga and Billangana originating from the Katling glacier. Major towns: Gangotri, Uttarkashi, Budhakedar and New Tehri.
Alaknanda basin
The Alaknanda drains Gangotri (Northwest), Kamte group (North) and Nanda Devi (Northeast). Major tributaries are Saraswati (Badrinath), Dhauli Ganga (Joshimath) Girthi Ganga, Mandakini (Kedarnath), Nandakini (Sutton), Pindar (Khati). The Alaknanda basin is bound by the Bhagirathi (West) and Sharda (East) basins.
Sharda basin
The final basin of the Western Himalayas is formed by Sharda and Goriganga rivers draining the Nanda Devi (Northwest) and Pangchuli (East) ranges. The Sharda river forms a natural boundary between India and Nepal. Major tributaries: Goriganga (Milan valley), Dharma Yankti (Dharma valley), Ramganga (Munsyari), Sarja (Baleshwar) and Chamaliya (Nepal). The Sharda basin is bound by the Alaknanda basin (West).
