A triangular-shaped feature of deposits at the mouths of many rivers is called a delta. It usually is in the shape of what is called an alluvial fan.
At the mouths of rivers.
because they needed water for everything
Erosion
Most rivers flow into the sea, so the mouths of them are located near the sea.
Deltas are areas of rich soil located at the mouths of many rivers. As rivers move downstream, they pick up soil from the river banks, later depositing it at the delta.
Sediment can accumulate at the mouths of rivers, usually in the form of deltas.
Parana river and urguay river
science
Freshwater and saltwater meet at the mouths of rivers that flow into the sea.
The ocean, obviously, just below the surface at the mouths of rivers and streams.
Falmouth is a town based at the mouth of the river fal.