a river in Briansk Oblast, RSFSR, and in Chernigov Oblast, Ukrainian SSR; a right tributary of the Desna River (Dnieper basin). The Sudost’ River is 208 km long and drains an area of approximately 6,000 sq km. Its source is on the southern edge of the Smolensk Plateau. The Sudost’ is fed mainly by snow, and its high-water period is in March and April. The mean flow rate 25 km from the mouth is 18.9 cu m per sec. The river freezes in November or December and opens up in late March or early April. Located on the Sudost’ is the city of Pochep.