Landforms created by the erosion, transport, and deposition of running water along the course of a river, from its mountain source to its mouth at the sea.
- Upper (youthful) course, dominated by erosion: V-shaped valleys, gorges and canyons, waterfalls, rapids, and potholes.
- Middle (mature) course, transport and some deposition: meanders (looping bends) and ox-bow lakes (cut-off meanders), plus river terraces.
- Lower (old) course, dominated by deposition: wide floodplains, natural levees, braided channels, and deltas at the mouth.
- A delta is a deposit at the mouth where a river meets a sea or lake; the Ganga-Brahmaputra forms the world's largest delta (the Sundarbans). An estuary, by contrast, is a funnel mouth with no delta, as with the Narmada and Tapi.
- The whole drainage area feeding a river is its basin, separated from neighbours by a watershed (divide).
The course-wise landforms, the ox-bow lake from a meander, and the delta versus estuary distinction (Ganga delta versus Narmada estuary) are very common matching and one-mark questions.
Delta (depositional, multiple distributaries, Ganga) versus estuary (single funnel mouth, no delta, Narmada and Tapi); meander (bend) versus ox-bow lake (abandoned bend); V-shaped river valley versus U-shaped glacial valley.
Rivers carve V-valleys and gorges upstream, meanders midstream, and floodplains and deltas downstream; Narmada and Tapi end in estuaries.