Prelims ask
Altai, Irtysh longer, north, Kara Sea, Gulf of Ob.
Asia
Ob
The system is a textbook top-ten river. The Irtysh alone is longer than the Ob above the confluence.
- Source
- Russian Altai, at the confluence of the Biya and the Katun. The Irtysh rises in the Altai of Mongolia and China.
- Countries
- Russia for the Ob. The Irtysh crosses China, Kazakhstan and Russia.
- Direction
- North.
- Mouth
- Gulf of Ob, Kara Sea, Arctic Ocean.
- Length
- About 5,410 km for the Ob–Irtysh system.
- Major tributaries
- Irtysh, Tobol, Chulym.
- Delta or estuary
- A long estuary, the Gulf of Ob. Not a bird-foot delta.
- Basin
- West Siberian Plain. Long ice cover. Oil and gas on the lower basin.
- One exam fact
- Arctic drainage. The long tributary is international; the named trunk in Russia is not the farthest source.
Mains use
Siberian north-flowing river. Pair with Yenisei and Lena, and contrast all three with the Amur.