RIVERS

RIVERS, water currents, flowing on their developed beds and feeding on the surface and underground runoff from their catchment basins. They flow in the lowered forms of relief — valleys. There is a source (place of origin) and a mouth (the place where the river flows into the sea or merges with another river). Depending on the peculiarities of R. feeding, there is snow melt flood, freshet, low water; according to the developed conditions there are plain, mountain, lake, marsh, karst rivers; according to length — small (up to 100 km), medium (100—500) and large (more than 500 km). R. in the Bashkir Pre‑Urals are mostly of the plain type (rivers Ai, Bystryi Tanyp, Dyoma, Karmasan, Usen, Ufa, Chermasan, etc). There are karst R.: Atysh‑sumgan, Aguyzgan (basin of the Lemeza river), Sarva, etc. The largest density of the river network is on the western slopes of the Bashkir (Southern) Urals (rivers Zigan, Zilim, Lemeza, Nugush, Sim, etc). In the folding zone R. are referred to the mountain type, associated with the bottoms of intermountain depressions, and cutting ridges (upper reaches of rivers Belaya, Inzer, Yuruzan, etc). In the Bashkir Trans‑Urals the river network has low density and regulation of flow (rivers Bolshoy Kizil, Maliy Kizil, Sakmara, Ural, Khudolaz). Belaya and Ufa rivers are navigable in the middle and lower reaches. Sarva and Yamanelga are natural monuments.