River Raptee

The West Rapti, also known as the Kuwano, is a river which drains Rapti Zone in Mid-Western Region, Nepal, then Awadh and Bhojpur-Purvanchal regions of Uttar Pradesh state, India before joining the Ghaghara. It is a major left bank tributary of the Ganges, and is also known as the Karnali in Nepal.

The West Rapti is notable for ''janajati'' ethnic groups – Kham Magar among its highland sources and then Tharu in Inner Terai Deukhuri Valley, for its irrigation and hydroelectric potential, and for recurrent floods that led to its nickname "Gorakhpur's Sorrow".

Max depth 8.50

Min depth 10.7

History

As ancient Airavati river

Aciravati, Achirvati or Airavati is the ancient name for a river has been identified with the modern Rapti, flowing through what is now Nepal and the northern portion of Uttar Pradesh. The Chinese pilgrim Xuanzang knew it as A-chi-lo. Jain texts mention it as Eravai.

The ancient city of Sravasti, once capital of Kosala Kingdom, stood on the western bank of the Achirvati. The river was a tributary of the Sarayu. It was one of the five great rivers that constituted the Ganges group of rivers and one of the sacred rivers of the Buddhist midland.

Geography

The Rapti rises south of a prominent E-W ridgeline midway between the western Dhaulagiri Himalaya and the Mahabharat Range. A summit on this ridgeline marks a triple divide. North of the triple divide the Karnali and Gandaki basins are adjacent; south of it the Rapti and similar but smaller '' Babai River'' (; ) separate the two larger basins. After crossing into India, the Babai and Rapti separately join the Karnali's continuation called ''Ghaghara''. The Ghaghara ultimately joins the Ganges.

Hydrology

The Rapti's headwaters descend south from rugged highlands populated by Kham Magar. The western tributary ''Mādī Kholā'' () rises in northwestern Rolpa and is joined by ''Lungrī Kholā'' () draining northeastern Rolpa. The Mardi then crosses into Pyuthan. It is joined by east-flowing Arun Kholā () at Devithān () where it enters a gorge through the Mahabharat Range.

''Jhimruk Kholā'' () -- east of the Mardi—mainly drains Pyuthan. Below the upper highlands, an alluvial valley opens where Brahman
and Chhetri rice farmers irrigate paddy fields. At ''Cherneta'', Pyuthan the Jhimruk approaches within 1.5 km of the Mardi and a 12 megawatt hydroelectric plant exploits the Jhimruk being 200 meters higher.

Below Cherneta the Jhimruk loops east, becoming the border between Pyuthan and Arghakhanchi District. Its valley narrows and steepens as it enters the Mahabharat Range. Partway through it joins the Mardi and the combined flow is then named the Rapti. The main river emerges from its gorge into the lower Siwalik Hills and Dang District. At Bhalubang Bazaar Nepal's east-west Mahendra Highway bridges the river.

Below Bhalubang, Inner Terai ''Deukhuri Valley'' opens between the ''Dang'' and '' Dudhwa Ranges'', both sub ranges of the Siwaliks. Valley, following the WNW trend of the Siwalik hills for 100 km. Although the land is fertile, before DDT came into use in the 1950s Deukhuri was so malarial that only the Tharu people who had genetic resistance could be confident of surviving the warmer months.

The river crosses from Dang into Banke District. Approaching Nepalganj—largest town in Nepal's western Terai—the Dudhwa Hills fall away and the river turns SE, crossing into Uttar Pradesh, India and flowing through districts Shravasti, Siddharth Nagar, Basti, Sant Kabir Nagar, Maharajganj District and Gorakhpur, passing Gorakhpur city at about 135 air miles (215 km) from Nepal.

Just west of the city it is joined by the smaller Rohini rising further east in Nepal's Nawalparasi and Rupandehi Districts, draining 794 km² in Nepal then 1892 km² following through Maharajganj District in India. 60 km beyond Gorakhpur the Rapti joins the Ghaghara (Karnali) at Rajpur. About 120 km further on at Chhapra, the Ghaghara reaches the Ganges.

Resource utilisation

The Rapti's flow has great seasonal variation because the river lacks sources in high elevation glaciers and snowfields to buffer pre-monsoon drought. Average monthly flows at '' Jalkundi'' (27°58'N, 82°14'E) in Deukhuri Valley vary from 17.6 m³/s in pre-monsoon April to 451 m³/s at the peak of the monsoon in August. Maximum recorded flood was 7,390 m³/s on 10 September 1981. 100-year flood flows are predicted at 10,100 m³/s. Every year, floods threaten over 700,000 acres (280,000 ha) in Uttar Pradesh.

Flood control projects under study include a dam at Jalkundi that would inundate of farmland in Deukhuri Valley. An alternative dam site is upstream at ''Naumure'' on the Pyuthan-Dang district border (27°53'N, 82°48'E). This would be an earthen dam 169 m high with 351 million cubic meters live storage capacity, storing excess monsoon flows for irrigation use during the following dry season and generating up to 207 megawatts. Impoundment would mainly be in gorges through the Mahabharat Range, inundating less farmland than the Jalkundi alternative. Plans are also underway for three irrigation sub-projects – Kapilvastu District involving interbasin water transfer to the southeast, Deukhuri Valley , and Banke District .

References

External links

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{{Hydrography of Uttar Pradesh

Rivers of Lumbini Province
Hydroelectric power stations in Nepal
Rivers of Uttar Pradesh
International rivers of Asia
Ancient Indian rivers
Sacred rivers
Rivers in Buddhism
Ghaghara