riverbanks
The sides are known as the river bank or river banks.
the banks
Seine
The town of Bridgwater lies along both sides of the River Parrett.
The Nile River
The nonparallel sides of a trapezoid are called the legs. The parallel sides are called the bases.
The sediments deposited along the sides of a river are called "levees." These natural barriers form from the accumulation of silt and clay during flooding events, as the river overflows its banks and slows down, allowing sediment to settle. Levees can help to contain river flow and protect adjacent land from flooding.
The name of the river that runs through Augusta is called the Savannah River. Close by to the river is a nuclear power plant called Savannah River site.
The river in Leeds is called the River Aire.
The sides are known as the river bank or river banks.
It is called Enneagon for eleven sides.
A Canyon