River
Kosi River
729 km from source to mouth · India and Nepal.
India and NepalFlows into Ganges
In numbers
Length
729km
Average flow
2,300m³/s
Basin
29,400km²
Drop
4,306m
from 4,332 m to 26 m
Countries
2
The journey
From source to mouth
729 km of river and 2 stops on the way: 0 towns and cities on its banks, dams, bridges and the tributaries that feed it.
- 0 kmArun Riverat 4,332 m
- 270 kmSun Kositributary
- 355 kmKoshi Barrage
- 729 kmGangesat 26 m
Water level along the river (RiverATLAS; the height is exaggerated). Towns: GeoNames and Wikidata; bridges, dams and tributaries: Wikidata.
River in China, Nepal and India
At the mouth it carries 2,293 m³/s on average: an Olympic pool every 1.1 seconds. It drops from 4,332 m to 26 m, 5.9 m per kilometre on average. Its basin covers 29,400 km², about the size of AM. 35.7 million people live in it. Highest water: from August to September; lowest: from January to April. No large dam holds it back: it is one of the world's free-flowing rivers.
Where to start
- ColgongLargest city on its banks · 33,700 people
- Biratnagar Airport (BIR)Nearest airport with scheduled flights, 136 km from the cityCar hire at CCU airport (Kolkata)Discover Cars · Affiliate link↗
- From November to MarchThe best months to visit
Kosi River, month by month
Highest water: from August to September
Lowest water: from January to April. Best months to visit: from November to March.
From about 470 m³/s in the lowest month to 6,800 m³/s in the highest. An estimate: the monthly flow is modelled from the lowest and highest months of WaterGAP (RiverATLAS, 1971–2000) and the rain and snow along the river (WorldClim). Dams change the real rhythm. The chip is the average air temperature; below it, the month's rain.
Plan the trip
Plan the trip: boat trips, a bed by the river, a car
Some links above are affiliate links: if you book through them we may earn a commission, at no extra cost to you. It never changes what the data on this page says.
The basin
Kosi River: the basin in numbers
88,185 km² of land send their water to this river. This is what lives on it.
- 35.7millionpeople live in the basin
- 406/km²people per km²
- 2,419maverage altitude of the basin
- 1,038mmof rain a year (basin average)
- 12.3°Caverage air temperature
- 34%protected areas
- 0.1%covered by lakes
- 5%glaciers
- 16%permafrost
- 0.1km³held in reservoirs
What covers the basin
- 19% Forest
- 28% Cropland
- 21% Pasture
- 9% Towns and cities
- 5% Ice
RiverATLAS (HydroATLAS v1.0, CC BY 4.0): land cover, people, protected areas, glaciers and dams over the whole basin upstream of the mouth.
Along the river
Kosi River: what you find on the way
- 2Weirs
- 1River beachesBeachon
From OpenStreetMap, within 2.4 km of the river. Not mapped is not the same as not there.
From space
The source and the mouth, seen from orbit
Sentinel-2 cloudless 2016 by EOX IT Services GmbH (contains modified Copernicus Sentinel data 2016), CC BY 4.0. The glowing line is the river as drawn by RiverATLAS.
Photos
Kosi River in pictures
Tributaries
Where it flows, and what flows into it
It flows into
GangesIndia2,525 km12,000 m³/sTributaries (2)
Also: Bagmati River, Sun Kosi
In the same basin
India2,900 km19,500 m³/sYamunaIndia1,376 km3,500 m³/sPadma River
Bangladesh120 km32,000 m³/sGandaki RiverIndia630 km1,800 m³/sChambal RiverIndia960 km600 m³/sJamuna RiverBangladesh245 km20,100 m³/sGhaghara RiverIndia1,080 km3,300 m³/sTeesta RiverBangladesh470 km1,300 m³/sGomti RiverIndia900 km230 m³/sSon RiverIndia780 km1,200 m³/sNearby
Rivers nearby
India360 km390 m³/s149 km awayArun River
China530 km1,300 m³/s167 km awayGandaki RiverIndia630 km1,800 m³/s210 km awayTeesta RiverBangladesh470 km1,300 m³/s243 km awaySon RiverIndia780 km1,200 m³/s239 km awayDudh KoshiNepal138 km180 m³/s210 km awayGhaghara RiverIndia1,080 km3,300 m³/s263 km awaySankosh RiverIndia320 km5,400 m³/s265 km awayWhere these numbers come from
| Name, length, places | Wikidata (Q695610) · CC0 |
|---|---|
| Course, profile, basin | RiverATLAS v1.0 (HydroATLAS, Linke et al. 2019) · CC BY 4.0 — followed from the source to the mouth given by Wikidata |
| Flow | WaterGAP (RiverATLAS), 1971–2000 · CC BY 4.0 |
| Climate along the river | WorldClim (RiverATLAS), 1970–2000 · CC BY 4.0 |
| Towns, bridges, dams | Wikidata · CC0; GeoNames · CC BY 4.0 |
| Along the river | © OpenStreetMap contributors · ODbL |
| Images | EOX Sentinel-2 cloudless 2016 · CC BY 4.0; Wikimedia Commons |
Every source and licence is on the data sources page.
The family
Do you prefer beaches, lakes, mountains, waterfalls, islands, rivers or canyons?
Same idea, other landscapes: field atlases built on open data, month by month, in seven languages.
beaches
Find your beach: sea temperature, sun and swimming month by month.Visit 
lakes
Every lake on Earth: water temperature, ice, depth and the shore.Coming soonVisit 
mountains
Every summit in 3D: summit weather, the 0 °C line, huts and trails.Visit 
waterfalls
Every waterfall: height, flow month by month and when it roars.Coming soonVisit 
islands
Every island from the sea up: size, sea temperature, ferries and 3D.Coming soonVisit 
rivers
Every river from source to sea: the journey, the flow and the basin in numbers.You are here
canyons
Every canyon cut to scale: depth to the floor, rim and floor temperatures, trails and viewpoints.Coming soonVisit