Erosion, transportation and deposition all occur in a river. Moving from the upper course to the lower course, the rates of erosion, transportation and deposition change.
When the river loses energy, it drops any of the material it has been carrying. This is known as deposition.
Factors leading to deposition:
shallow water
slower velocity at the end of the river's journey, at the river's mouthThe place where a river meets the sea. and on the inside bends of meanderA bend in a river.