an old river
That flat plain formed by river deposits during a flood is known as a floodplain. It typically consists of fertile soil and is susceptible to periodic flooding due to its proximity to the river. Floodplains play an important role in natural ecosystems and agriculture.
Meander
A flood plain is a flat or gently sloping area near a river or stream that is prone to flooding. It forms when the river overflows its banks and deposits sediment on the adjacent land. Over time, this repeated flooding creates the flat surface of a flood plain.
You are referring to an oxbow lake. Oxbow lakes form as a river deposits sediment and changes course over time.
The flood plain. Delta
A floodplain.
a canyon, gorge or vale
In its flood plain
No, the area drained by a river is a river basin or drainage basin. The flood plain is in the lower valley reaches, where heavy rain can cause the river to flood, often bursting over flood defences, and for the water to flood over a large area.
It is the flood plain.
A 'flood plain' usually.
The narrow strip of land on both sides of the rivers is called cover flood plains