ObIrtysh

The Ob-Irtysh, also written as Ob–Irtysh, is the combined river system of the Ob River and its major tributary, the Irtysh, located in Western Siberia, Russia, with portions in Kazakhstan. The Irtysh rises in the Altai Mountains and flows generally west-northwest through Kazakhstan and Russia, joining the Ob near Omsk to form the Ob–Irtysh river system. The Ob then continues north and west across Western Siberia to empty into the Gulf of Ob, which opens into the Arctic Ocean.

The Irtysh is one of Asia’s longest rivers, about 4,000–4,300 kilometers in length; the Ob is about 3,700 kilometers long. The combined basin covers roughly 2.9 million square kilometers, draining much of Western Siberia.

The Ob–Irtysh system supports major economic activity, including hydroelectric power generation, navigation, and fisheries. The basin hosts several large cities, including Omsk on the Irtysh and Novosibirsk along the Ob. Water projects, dams, and reservoirs regulate flow and provide irrigation and flood control, but environmental pressures include pollution and habitat alteration.

Historically, the system has been a key transportation route in Siberia and a focus of Russian expansion into Siberia from the 17th century onward. The Ob–Irtysh is noted for its role in the regional economy and as a major Arctic drainage basin.