Ghaggar-Hakra river

The Ghaggar-Hakra River ( IPA: [ɡʰəɡːəɾ ɦəkɾaː]) is an intermittent river in India and Pakistan that flows in force only during the monsoon season. The river is known as Ghaggar before the Ottu barrage, and as Hakra downstream of the barrage in the Thar Desert. In pre-Harappan times the Ghaggar was a tributary of the Sutlej. It is still connected to this paleochannel of the Sutlej, and possibly the Yamuna, which ended in the Nara River, presently a delta channel of the Indus River joining the sea via Sir Creek.

The Sutlej changed its course about 8,000–10,000 years ago, leaving the Ghaggar-Hakra as a system of monsoon-fed rivers terminating in the Thar Desert. The Indus Valley Civilisation prospered when the monsoons that fed the rivers diminished around 5,000 years ago, and a large number of sites from the Mature Indus Valley Civilisation (2600–1900 BCE) are found along the middle course of the (dried-up) Hakra in Pakistan. Around 4,000 years ago, the Indus Valley Civilisation declined when the monsoons further diminished, and the Ghaggar-Hakra dried up, becoming a small seasonal river.