1.
Introduction
The Indus River is one of the world?s great trans-Himalayan rivers, flowing some 3,180 km from its
sources on the Tibetan Plateau to the Arabian Sea in Pakistan. Its basin, covering roughly 430,000
sq mi (1,120,000 km²), spans four countries?China, India, Afghanistan, and Pakistan?with the vast
majority in Pakistan and India. For millennia it has sustained agriculture, powered civilizations, and
acted as a natural boundary and cultural artery in South Asia.
2. Source and Upper Course
2.1 Tibetan Origins
- Headwaters arise at ca. 5,150 m elevation, northeast of Mount Kailash in western Tibet, from
springs and glaciers in the Gangdise-Himalaya range.
- For the first ~500 km the river cuts through deep gorges, rushing past peaks exceeding 7,000 m;
its flow here is dominated by glacial melt and snow-runoff.
2.2 Transboundary Stretch
- After leaving Tibet, the Indus enters Ladakh (India) and flows through the Gilgit-Baltistan region of
Pakistan, where it receives major upper tributaries like the Shyok and Shigar rivers.
- This zone is seismically active and subject to catastrophic glacial-lake outburst floods (GLOFs),
which have shaped its valley morphology.
3. Middle Course: The Punjab Plain
3.1 Entry into the Plains
- Exiting the mountains near Nanga Parbat, the river turns sharply southwest and spills onto the
plains of Pakistan?s Punjab region.
- Here it is joined by the five great 'eastern' tributaries?Jhelum, Chenab, Ravi, Beas, and
Sutlej?which together give Punjab (?five waters?) its name.
3.2 The Five Punjab Tributaries
Jhelum, Chenab, Ravi, Beas, Sutlej: see detailed table in full text.
4. Lower Course and Delta
4.1 Panjnad and Desert Crossing
- The combined waters of the five tributaries become the Panjnad River, which flows ~72 km to join
the Indus near Mithankot.
- From here the Indus traverses the Thar Desert, losing much volume to irrigation and evaporation,
yet carving fertile channels.
4.2 Delta and Distributaries
- Near Thatta, the Indus bifurcates into two main distributaries: the Arabian Sea Outlet and the
Hamun-e Mashkel channel.
- Historically it had seven principal branches: Han, Puran, Kalri, Barat, Pat, Khi, and Baghar?most
now silted or diverted by barrages.
- The delta spans ~6,000 sq km, supporting mangrove forests (Avicennia marina) and unique
coastal ecosystems.
5. Hydrology and Seasonal Variability
5.1 Snow-Fed Regime
- The hydrograph shows low winter flows (Dec-Feb), rising discharges in spring (Mar-Jun) from
snow-melt, and peak floods during the monsoon (Jul-Sep).
5.2 Monsoon Influence
- Although primarily glacial, ~25?40% of the Indus?s water derives from summer rains; inter-annual
monsoon variability drives flood risk in Pakistan?s Sindh province.
6. Irrigation and Dams
6.1 Ancient Canal Networks
- Harappan civilization first harnessed Indus waters via earthen canals by ~2500 BCE; remains of
early barrages have been found near Mohenjo-Daro.
6.2 Modern Engineering
- Mangla Dam (1967, on the Jhelum): 1,150 MW capacity, crucial for Pakistan?s water storage.
- Tarbela Dam (1976, on the Indus near Haripur): earth-filled reservoir backing 3,478 MW, among
world?s largest earth dams.
- Sukkur Barrage (1932): one of world?s largest irrigation structures, irrigating 8 million acres in
Sindh.
7. The Indus Waters Treaty
- Signed 1960 between India and Pakistan under World Bank auspices, allocating eastern rivers
(Ravi, Beas, Sutlej) to India, western rivers (Indus, Jhelum, Chenab) to Pakistan.
8. Ecology and Challenges
8.1 Biodiversity
- Riverine habitats support the Indus dolphin (Platanista gangetica minor), marsh crocodiles
(Crocodylus palustris), and migratory waterfowl.
8.2 Pollution & Over-Extraction
- Industrial effluents, agricultural runoff, and untreated sewage threaten water quality, especially
downstream of Sukkur.
- Groundwater over-draft in the Indus basin has led to falling water tables and salinization of soils.
9. Cultural and Historical Significance
9.1 Cradle of Harappan Civilization
- Cities like Harappa and Mohenjo-Daro (c. 2600-1900 BCE) flourished on its floodplains, developing
urban planning, drainage, and trade networks.
9.2 Literary References
- The river is mentioned in the Rigveda as Sindhu, and in Persian and Greek texts (as "Indos" and
"Sinthus"), highlighting its role in ancient commerce and empire.
10. Socio-Economic Importance Today
- The Indus basin irrigates over 16 million hectares, feeding ~140 million people in Pakistan alone.
- It underpins major crops: wheat, rice, cotton, and supports the textile industry in Punjab and Sindh.
11. Memory Aids and Revision Mnemonics
- ?15 Upstream, 5 Punjab, 2 Delta?: 15 major tributaries (incl. Kabul, Shyok), 5 Punjabi (Jhelum,
Chenab?), 2 principal distributaries.
- ?INDUS?: I: Indo-Tibetan source; N: Northern gorges; D: Delta channels; U: Upstream dams; S:
Sindh plains.
