a river in Stavropol’ Krai, RSFSR; a left tributary of the Kuban’. It rises from two sources, the Psysh and the Kizgych, which converge after flowing down from the northern slopes of the Glavnyi, or Vodorazdel’nyi, Ridge of the Greater Caucasus. The Bol’shoi Zelenchuk is 158 km long and drains a basin of 2,730 sq km. It is a typical mountain river. It is fed by a combination of rain, snow, melting glaciers, and underground sources. At the stanitsa (large cossack village) of Ispravnaia, 80 km from its mouth, the Bol’shoi Zelenchuk discharges water at an average rate of 40 cubic meters per second. It has a left tributary, the Kiafar. It is used for floating timber.