a river in the Chuvash and Tatar ASSR’s; a left-bank tributary of the Sviaga River (in the Volga basin). Length, 176 km; basin area, 2,480 sq km.
The Kubnia flows along the northern edge of the Volga Up-land, forming a number of oxbow lakes. The river is fed primarily by rain. Its average rate of flow 29 km from its mouth is 4.2 cu m per sec. It freezes over in late November or early December and thaws out in April. The river’s principal tributary is the Sugut, a left-bank tributary. The Kubnia is used for floating logs.