River
Oka
630 km from source to mouth · Russia.
RussiaFlows into Bratsk Reservoir
In numbers
Length
630km
Average flow
270m³/s
Basin
34,000km²
Drop
1,405m
from 1,795 m to 390 m
Country
1
The journey
From source to mouth
630 km of river and 4 stops on the way: 0 towns and cities on its banks, dams, bridges and the tributaries that feed it.
- 0 kmSourceat 1,795 m
- 88 kmTissatributary
- 114 kmBaga-Zjombolok
- 114 kmZhomboloktributary
- 345 kmZimatributary
- 630 kmBratsk Reservoirat 390 m
Water level along the river (RiverATLAS; the height is exaggerated). Towns: GeoNames and Wikidata; bridges, dams and tributaries: Wikidata.
River in Irkutsk Oblast, Russia
At the mouth it carries 274 m³/s on average: an Olympic pool every 9.1 seconds. It drops from 1,795 m to 390 m, 2.2 m per kilometre on average. Its basin covers 34,000 km², about the size of MD. 140,000 people live in it. Highest water: July; lowest: from January to April. No large dam holds it back: it is one of the world's free-flowing rivers.
Where to start
- ZimaLargest city on its banks · 33,323 people
- Irkutsk International Airport (IKT)Nearest airport with scheduled flights, 242 km from the city
- On the water2 ferry piers, marinas, boat rentals and boat ramps along the river (OpenStreetMap)
- Kayak and canoe9 put-ins and rapids mapped (OpenStreetMap)
- From June to AugustThe best months to visit
Oka, month by month
Highest water: July
Lowest water: from January to April. Freezing months (average below −4 °C): from November to March. Best months to visit: from June to August.
From about 30 m³/s in the lowest month to 770 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
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The basin
Oka: the basin in numbers
40,687 km² of land send their water to this river. This is what lives on it.
- 140,000people live in the basin
- 4/km²people per km²
- 1,174maverage altitude of the basin
- 396mmof rain a year (basin average)
- -4.9°Caverage air temperature
- 0.9%covered by lakes
- 43%permafrost
What covers the basin
- 67% Forest
- 8% Cropland
- 2% Pasture
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
Oka: what you find on the way
- 3Waterfalls
- 9Rapids
- 2Ferry piers
From OpenStreetMap, within 2.2 km of the river. Not mapped is not the same as not there.
Cross-checked with our atlases
Oka in our other atlases
What our sister atlases know about the waterfalls on this river, the lakes it flows through, the beaches at its mouth, the mountains where it rises and the islands off its mouth.
1waterfall on the riverCascadyas
Waterfalls (1)
On the river, by Cascadyas
- Baga-Zjombolokkm 148
Cascadyas is coming soonOpen Cascadyas ↗
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.
Tributaries
Where it flows, and what flows into it
Tributaries (5)
Also: Tissa, Zhombolok, Zima, Tagna, Dibi
In the same basin
Russia3,487 km19,800 m³/sAngaraRussia1,779 km4,500 m³/sNizhnyaya TunguskaRussia2,989 km3,700 m³/sSelengaRussia1,024 km940 m³/sPodkamennaya TunguskaRussia1,865 km1,600 m³/sOrkhon River
Mongolia1,124 km120 m³/sAbakanRussia514 km380 m³/sUdaRussia1,203 km300 m³/sIrkutRussia488 km140 m³/sTuul RiverMongolia704 km37 m³/sWhere these numbers come from
| Name, length, places | Wikidata (Q288695) · 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 |
| Our other atlases | Cascadyas — Wikidata · CC0; © OpenStreetMap contributors · ODbL; GeoNames · CC BY 4.0; HydroLAKES · CC BY 4.0; NOAA OISST |
Every source and licence is on the data sources page.
The family
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