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".

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.

[2][3] The Rapti rises south of a prominent E-W ridgeline midway between the western Dhaulagiri Himalaya and the Mahabharat Range.

Below the upper highlands, an alluvial valley opens where [[Brahman ]] and Chhetri rice farmers irrigate paddy fields.

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.

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.

[4][5][6][7] The Rapti's flow has great seasonal variation because the river lacks sources in high elevation glaciers and snowfields to buffer pre-monsoon drought.

[citation needed] Flood control projects under study include a dam at Jalkundi that would inundate 71,000 acres (29,000 ha) of farmland in Deukhuri Valley.

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.