The Himalayas is one of the most geologically  active mountains ranges in the world. It have a complex drainage system that and been shaped by various geological process like river piracy. River piracy also known as stream piracy is a geomorphological phenomenon occurring when a stream or river drainage system or watershed is diverted from its own bed and flows down the bed of a neighboring stream.

Role of River Piracy

1.  Capture of Rivers : River piracy has resulted in capture of one river from another which leads to change in the drainage system. Eg: The Satluj river was once a tributary of Indus but was later captured by the Ganges
2. New River Formation : The formation of river Bhagirathi is an example of new river formation due to river piracy as the Alakananda river captured river bed of Bhagirathi River.
3. River Course : The shift in the Arun Kosi river, a tributary of Kosi river, when captured by the Phung Cho river is an example of change in river course by river piracy.
4. Creation of Gorges & Canyons: The River Piracy has led to the formation of various gorges and Canyons. Eg: Kali Gandaki gorge was formed when Kali Gandaki River was captured by Mustang River.

The current Himalayan drainage system is a result of the complex geological activities like river piracy, which has led to the formation of new rivers,  change in river courses and creation of Gorges and Canyons. The unique drainage pattern, high sediment loads and dynamic landscapes of himalayas are results of various geological process including river piracy.