The Kosmaj is source of several rivers. Turija river (and several of its tributaries, including Sibnička reka), which springs right below the mountain and flows to the west into the Kolubara River. Other originate below the Parcanski vis: Lug (or Veliki Lug) which flows to the east into the Kubršnica, Ralja also flows to the east into the Jezava, outflow of the Velika Morava, and Topčiderka which flows to the north, into the urban center of Belgrade.