Flood plains

A flood plain is the wide, flat area of land on either side of the river in its middle and lower course. A flood plain forms through both erosion and deposition. When material is deposited on the slip off slope of a meander it gradually builds up over time. When a river overflows its banks, water pours on to the floodplain and as it drains away fine material (alluvium) is deposited.

Levees 

Levees are natural embankments of silt along the banks of a river, which are often several metres higher than the flood plain.

Deltas 

A delta is a flat area of sand and silt built into the sea. When a river enters the sea carrying large volumes of fine material, the velocity slows and causes the load to be deposited in layers. Over time, the deposited material forms small islands separated by river channels called distributaries.