By depositing sewage waste and human feces along its banks, thereby creating what we scientists like to call "structural webbing" which then acts as a binding glue for other silty, organic deposits to latch onto.
In a sense, a delta is made from the land drained by a river. Fine particles of earth are washed down the river to its mouth. At the mouth, the waters are calmer, and many of the particles drop out to the bottom of the sea, building the land up. Vegetation that can live at the edge of the sea build it up more. Tides and floods build it up more. Eventually the land mass at the mouth of the river is extended in this way. The source of the earth that is at the delta, is the earth washed from the drainage area of the river.
so that they won't fall into the river
Due to the movement of the plate tectonics land mass will start to build up and mountains will build up.
build up land
Deltas are created when a thick river with slowing meanders deposit the sediment and rocks build up and create new land. This new land causes the river or stream to break apart and creates branches. A delta is now created.
It leaves silt that builds up the land around the river banks.
Glaciers are forces of erosion of the land they tend to do the opposite of build it up, they wear it down. However they do deposit moraines and when they melt the land springs up a little.
A river delta.
deposition
deposition
Levee
Levee