Yamuna

The Yamuna is the second-largest tributary river of the Ganges by discharge and the longest tributary in India. Originating from the Yamunotri Glacier at a height of about on the southwestern slopes of Bandarpunch peaks of the Lower Himalaya in Uttarakhand. It then travels from the mountainous, cultural and geographical Mahasu region, and then enters the Indo-Gangetic plains of Uttar Pradesh and Haryana. It travels and has a drainage system of, 40.2% of the entire Ganges Basin. It merges with the Ganges at Triveni Sangam, Prayagraj, which is a site of the Kumbh Mela, a Hindu festival held every 12 years.
Like the Ganges, the Yamuna is highly venerated in Hinduism and worshipped as the goddess Yamuna. In Hinduism, she is believed to be the daughter of the sun god, Surya, and the sister of Yama, the god of death, and so she is also known as Yami. According to popular Hindu legends, bathing in Yamuna's sacred waters frees one from the torments of death.
The river crosses several states such as Haryana, Himachal Pradesh, Uttar Pradesh, Uttarakhand and Delhi. It also meets several tributaries along the way, including Tons, Chambal, its longest tributary which has its own large basin, followed by Sindh, the Betwa, and Ken. From Uttarakhand, the river flows into the state of Himachal Pradesh. After passing Paonta Sahib, Yamuna flows along the boundary of Haryana and Uttar Pradesh and after exiting Haryana it continues to flow till it merges with the river Ganges at Sangam or Prayag in Prayagraj. It helps create the highly fertile alluvial Ganges-Yamuna Doab region between itself and the Ganges in the Indo-Gangetic Plain.
Nearly 57 million people depend on the Yamuna's waters, and the river accounts for more than 70 percent of Delhi's water supply. It has an annual flow of 97 billion cubic metres, and nearly 4 billion cubic metres are consumed every year. At the Hathni Kund Barrage, its waters are diverted into two large canals: the Western Yamuna Canal flowing towards Haryana, and the Eastern Yamuna Canal flowing towards Uttar Pradesh. Beyond that point the Yamuna is joined by the Somb, a seasonal rivulet from Haryana, and by the highly polluted Hindon River near Noida, by Najafgarh drain near Wazirabad and by various other drains, so that it continues only as a trickling sewage-bearing drain before joining the Chambal at Pachnada in the Etawah District of Uttar Pradesh.
The water quality in Upper Yamuna, as the long stretch of Yamuna is called from its origin at Yamunotri to Okhla barrage, is of "reasonably good quality" until the Wazirabad barrage in Delhi. Below this, the discharge of wastewater in Delhi through 15 drains between Wazirabad barrage and Okhla barrage renders the river severely polluted. Wazirabad barrage to Okhla Barrage, stretch of Yamuna in Delhi, is less than 2% of Yamuna's total length but accounts for nearly 80% of the total pollution in the river. Untreated wastewater and poor quality of water discharged from the wastewater treatment plants are the major reasons of Yamuna's pollution in Delhi. To address river pollution, measures have been taken by the Ministry of Environment and Forests under the Yamuna Action Plan which has been implemented since 1993 by the MoEF's National River Conservation Directorate.

Basin

Palaeochannels: Sarasvati's tributary

The present Sarsuti river which originates in the Shivalik hills in Himachal and Haryana border and merges with Ghaggar River near Pehowa is the palaeochannel of Yamuna. Yamuna changed its course to the east due to a shift in the slope of the Earth's crust caused by plate tectonics.

Current channel

The river flows southwards for about, through the Lower Himalayas and the Shivalik Hills Range. Morainic deposits are found along the steep Upper Yamuna, highlighted with geomorphic features such as interlocking spurs, steep rock benches, gorges and stream terraces. Large terraces formed over a long period of time can be seen in the lower course of the river, such as those near Naugoan. An important part of its early catchment area, totalling, lies in Himachal Pradesh. The Tons, Yamuna's largest tributary, drains a large portion of the upper catchment area and holds more water than the main stream. It rises from the Hari-ki-dun valley and merges after Kalsi near Dehradun. The drainage system of the river stretches between Giri-Sutlej catchment in Himachal Pradesh and Yamuna-Bhilangna catchment in Uttarakhand, also draining the ridge of Shimla. Kalanag is the highest point of the Yamuna basin. Other tributaries in the region are the Giri, Rishi Ganga Kunta, Hanuman Ganga and Bata, which drain the upper catchment area of the Yamuna basin.
From the upper catchment area, the river descends onto the plains of Doon Valley, at Dak Pathar near Dehradun. Flowing through the Dakpathar Barrage, the water is diverted into a canal for power generation. Further downstream, the Assan River joins the Yamuna at the Asan Barrage, which hosts a bird sanctuary. After passing the Sikh pilgrimage town of Paonta Sahib, the Yamuna reaches Tajewala in Yamuna Nagar district of Haryana. A dam built here in 1873 is the origin of two important canals, the Western and Eastern Yamuna Canals, which irrigate the states of Haryana and Uttar Pradesh. The Western Yamuna Canal crosses Yamuna Nagar, Karnal, Panipat and Sonipat before reaching the Haiderpur treatment plant, which contributes to Delhi's municipal water supply. The Yamuna receives wastewater from Yamuna Nagar and Panipat cities; beyond this it is replenished by seasonal streams and groundwater accrual. During the dry season, the Yamuna remains dry in many stretches between the Tajewala dam and Delhi, where it enters near the Palla barrage after traversing.
The Yamuna defines the state borders between Himachal Pradesh and Uttarakhand, and between Haryana, Delhi and Uttar Pradesh. When the Yamuna reaches the Indo-Gangetic plain, it runs almost parallel to the Ganges, the two rivers creating the Ganges-Yamuna Doab region. Spread across, one-third of the alluvial plain, the region is known for its agricultural output, particularly for the cultivation of basmati rice. The plain's agriculture supports one-third of India's population.

State	Catchment area	% of catchment area
Uttar Pradesh and Uttarakhand	74,208	21.5
Himachal Pradesh	5,799	1.6
Haryana	21,265	6.5
Rajasthan	102,883	29.8
Madhya Pradesh	140,230	40.6
Delhi	1,485	0.4

Subsequently, the Yamuna flows through the states of Delhi, Haryana and Uttar Pradesh before merging with the Ganges at a sacred spot known as Triveni Sangam in Prayagraj. Pilgrims travel by boats to platforms erected in midstream to offer prayers. During the Kumbh Mela, held every 12 years, large congregations of people immerse themselves in the sacred waters of the confluence. The cities of Baghpat, Delhi, Noida, Mathura, Agra, Firozabad, Etawah, Kalpi, Hamirpur, and Prayagraj lie on its banks. At Etawah, it meets it another important tributary, Chambal, followed by a host of tributaries further down, including, Sindh, the Betwa, and Ken.

Important tributaries

Yamuna's tributaries make up 70.9% of the catchment area and the river has six important tributaries:

Tons River is Yamuna's largest tributary and rises in the Bandarpoonch mountain. It meets Yamuna below Kalsi, near Dehradun, Uttarakhand.
Hindon River originates from Upper Shivalik, in the Lower Himalayan Range. It is a rain fed river and has a catchment area of and traverses.
Chambal River, also known as Charmanvati in ancient texts, flows through Rajasthan and Madhya Pradesh and traverses a total distance of from its source in the Vindhya Range, near Mhow. It has a drainage basin of and it supports hydro-power generation at Gandhi Sagar dam, Rana Pratap Sagar dam and Jawahar Sagar dam. The Chambal river merges with the Yamuna at Sahon village.
Kali River, rises in the Doon Valley and merges with the Hindon River.
Ken River, flows through Madhya Pradesh and Uttar Pradesh. It originates near Ahirgawan village in Jabalpur district and travels a distance of before merging with the Yamuna at Chilla village, near Fatehpur in Uttar Pradesh. It has an overall drainage basin of.
Betwa River originates in Bhopal district, in Madhya Pradesh. Its confluence with the Yamuna is in Hamirpur district, Uttar Pradesh. It has a catchment area of.
Background

Etymology

The name Yamuna seems to be derived from the Sanskrit word "yama", meaning 'twin', and it may have been applied to the river because it runs parallel to the Ganges.

History

The earliest mention of Yamuna is found at many places in the Rig Veda, which was composed during the Vedic period BCE, and also in the later Atharvaveda, and the Brahmanas including Aitareya Brahmana and Shatapatha Brahmana. In the Rigveda, the story of the Yamuna describes her "excessive love" for her twin, Yama, who in turn asks her to find a suitable match for herself, which she does in Krishna.
Yamuna is mentioned as Iomanes in the surveys of Seleucus I Nicator, an officer of Alexander the Great and one of the Diadochi, who visited India in 305 BCE. Greek traveller and geographer Megasthenes visited India sometime before 288 BCE and mentioned the river in his Indica, where he described the region around it as the land of Surasena. In Mahabharata, the Pandava capital of Indraprastha was situated on the banks of Yamuna, considered to be the site of modern Delhi.
Geological evidence indicates that in the distant past the Yamuna was a tributary of the Ghaggar River. It later changed its course eastward, becoming a tributary of the Ganges. While some have argued that this was due to a tectonic event, and may have led to the Sarasvati River drying up, the end of many Harappan civilisation settlements, and creation of the Thar Desert, recent geological research suggests that the diversion of the Yamuna to the Ganges may have occurred during the Pleistocene, and thus could not be connected to the decline of the Harappan civilisation in the region.
Most of the great empires which ruled over a majority of India were based in the highly fertile Ganges–Yamuna basin, including the Magadha, Maurya Empire, Shunga Empire, Kushan Empire, and Gupta Empire, and many had their capitals here, in cities like Pataliputra or Mathura. These rivers were revered throughout these kingdoms that flourished on their banks; since the period of Chandragupta II, statues both the Ganges and Yamuna became common throughout the Gupta Empire. Further to the South, images of the Ganges and Yamuna are found amidst shrines of the Chalukyas, Rashtrakutas, and on their royal seals; prior to them, the Chola Empire also added the river into their architectural motifs. The Three River Goddess shrine, next to the Kailash rock-cut Temple at Ellora, shows the Ganges flanked by the Yamuna and Saraswati.