Aggradation

Aggradation is when sand, rocks, or other small materials pile up in a river or stream. Think of it like building a sandcastle: you keep adding more and more sand until it makes a big pile. The same thing happens in rivers and streams, but it takes a lot longer.

The river or stream carries these small materials downstream and as the water loses its energy, it drops the sand or rocks it was carrying. Over time, these materials build up and make the bottom of the river or stream higher. This can change the way the water flows and where the water goes, like when your sandcastle gets so big that it blocks the path of the water.

Aggradation can happen naturally or it can be caused by humans, like when we build dams or other structures that slow down or change the flow of the water. It's an important process for shaping the landscape around us and can create habitats for different animals and plants.