Aggradation

Aggradation is the buildup of a land surface as deposited sediment raises its elevation. It occurs in river channels, floodplains, deltas, and other depositional settings.

Sediment transport: The movement of sediment by water, wind, ice, or gravity. Aggradation begins when transport delivers more sediment than a flow can carry onward.
Floodplain: A low-lying area beside a river that is periodically inundated by floods. Repeated overbank deposition aggrades floodplains and changes their elevation.
Degradation (geomorphology): The lowering of a land surface through erosion or removal of sediment. Degradation lowers channel beds, the opposite vertical trend from aggradation.
Sea-level change: A change in the elevation of the ocean surface relative to land. Rising sea level can create space for coastal and deltaic sediment to accumulate.
Yellow River: A major river of northern China known for its sediment-rich waters and shifting course. Its high sediment load has repeatedly raised channel beds and contributed to avulsions.
Sediment budget: An accounting of sediment entering, leaving, and accumulating within a defined area. A positive sediment balance raises the bed or depositional surface.
Delta: A sedimentary landform built where a river enters a standing body of water. Deltas grow as river-borne sediment accumulates and aggrades their surface.
Lateral accretion: The sideways addition of sediment to a landform, commonly along a migrating river channel. Lateral accretion builds outward rather than primarily raising a surface.
Tectonic subsidence: The gradual sinking of Earth's crust due to tectonic processes. Subsidence creates accommodation space that can be filled by aggrading deposits.
Mississippi River Delta: The network of sedimentary lobes built by the Mississippi River along the Gulf of Mexico. Its shifting depositional lobes record aggradation alongside subsidence and sea-level change.

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River terraceCompared with: Aggradation raises valley floors; later incision can preserve those levels as terraces.