The Ghaggar-Hakra River is an intermittent river in India and Pakistan that flows only during the monsoon season. The river is known as Ghaggar before the Ottu barrage at , 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.
Nineteenth and early 20th century scholars, but also some more recent authors, have suggested that the Ghaggar-Hakra might be the defunct remains of the Sarasvati River mentioned in the Rig Veda, fed by Himalayan-fed rivers, despite the fact that the Ghaggar-Hakra had dried up by that time.
River course
The basin consists of two parts, Khadir and Bangar. Bangar are the higher banks that are not flooded in rainy season, while khadar refers to the lower flood-prone area.
Ghaggar River
The Ghaggar is an intermittent river in India, flowing during the monsoon rains. It originates in the village of Dagshai in the Shivalik Hills of Himachal Pradesh at an elevation of above mean sea level and flows through Punjab and Haryana states into Rajasthan; just southwest of Sirsa, Haryana and by the side of Talwara Lake in Rajasthan.
Dammed at Ottu barrage near Sirsa, Ghaggar feeds two irrigation canals that extend into Rajasthan.
Tributaries of the Ghaggar
The main tributaries of the Ghaggar are the Kaushalya river, Markanda, Sarsuti, Tangri and Chautang.
The Kaushalya river is a tributary of Ghaggar river on the left side of Ghaggar-Hakra, it flows in the Panchkula district of Haryana state of India and converges with Ghaggar river near Pinjore just downstream of Kaushalya Dam.
Hakra River
The Hakra is the dried-out channel of a river near Fort Abbas City in Pakistan that is the continuation of the Ghaggar River in India. The Hakra-channel is connected to paleochannels of the Sutlej and the Yamuna, which ended in the Nara River, 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.
This Sutlej/Yamuna paleochannel streamed through Sindh, and its sign can be found in Sindh areas such as Khairpur, Nawabshah, Sanghar and Tharparkar.
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. IVC-sites have not been found further south than the middle of Bahawalpur district, and it has been assumed that the Hakra ended there in a series of terminal lakes.
Paleography
While there is general agreement that the river courses in the Indus Basin have frequently changed course, the exact sequence of these changes and their dating have been problematic.
Older publications have suggested that the Sutlej and the Yamuna drained into the Hakra well into Mature Harappan times, providing ample volume to the supply provided by the monsoon-fed Ghaggar. The Sutlej and Yamuna then changed course between 2500 BCE and 1900 BCE, due to either tectonic events or "slightly altered gradients on the extremely flat plains," resulting in the drying-up of the Hakra in the Thar Desert. More recent publications have shown that the Sutlej and the Yamuna shifted course well before Harappan times, leaving the monsoon-fed Ghaggar-Hakra which dried-up during late Harappan times.
Pre-Holocene
The paleo-channel of the Sutlej was active until the end of the Ice Age, some 10,000-8,000 years ago, emptying into the Rann of Kutch via the Nara river.