External River

Synonym: Exterior river ; Exorheic river

A river that flows directly or indirectly into the ocean is called an exorheic river. The basin of an exorheic river is called the outflow area, which usually comprises an extensive fluvial system with a large flow volume and perennial streams. Therefore, in an exorheic basin, alpine valleys, river terraces, sand bars and lateral bars usually form to make up an exorheic river landscape. In China, exorheic river basins cover 64% of the total area of the country. Under specific conditions, an exorheic river can transform into an endorheic river. For example, the Qinghai Lake fluvial system was previously connected to Huanghe (Yellow River), but it became endorheic due to changes in the geologic structures and the lowering of the lake surface. Eight rivers flow out of China: the Yarlungzagbo River (flows out from Tibet) via the Brahmaputra River (India), the Lancang River (flows out from Yunnan) via the Mekong River (Laos), the Nu River (flows out...