West Kazakhstan lies mostly within the Pre-Caspian Lowlands which extend southward into neighboring Atyrau(1) Province. These drop below sea level in southern West Kazakhstan. The Ural flows south from the province's north center and into Atyrau, marking the official continental boundary.
To the east lies a high dry plateau, the southern continuance of the Ural Mountains. The Emba River flows southwest from the plateau into Atyrau. South of it--still in Aqtobe are lowlands which connect the Pre-Caspian to the Turanian Lowlands. The southeast corner of Aqtobe includes a piece of the Aral Sea(2). To the northeast of this plateau is another one, the Turgay.
The Turgay Plateau is traditionally considered to have two parts, divided west from east by the Turanian Gate. This narrow belt, below 90 meters, connects the West Siberian and Turanian Lowlands. The western half of the plateau is drained by the Tobol(3) which flows northeast into the southernmost West Siberian Lowlands in Qostanay Province. Further south in that province, in the center of Qostanay, is the Turgay River which disappears into the desert.
(1) Also Spelled Atriau. Formerly Gorjev or Gor'yev.
(2) Asia's second largest lake, and probably the world's fourth largest.
(3) The Tobol flows into the Irtysh in Russia.