It leaves silt that builds up the land around the river banks.
it is what's left after water leaves..=]
lake
A floodplain is the land that is covered by water when a river overflows it's banks. When this happens, silt and clay are deposited over time and the land on either side of the river flattens out. Any depressions in the land will hold water when the river level returns to normal after flooding and therefore more clay and silt will be deposited there filling it up.
A delta.
delta
The answer is delta
Land formed at the mouth of a river by deposited silt is known as a delta. It typically forms when the river's velocity decreases as it meets the ocean, causing sediment carried by the river to be deposited, building up land over time.
Delta
Fine particles of fertile land that is deposited on the banks of a river after a flood
This land is called a delta and it is formed by the deposition of sediment carried by the river. The sediment, which includes silt and sand, is deposited when the river water slows down as it enters a larger body of water, causing the sediment to settle out and build up over time. Deltas are typically fertile areas due to the rich soil deposited by the river.
It help the farming of Egypt by brining silt to the land (silt is bits of rocks0
alluvial fan?