What is the term for the outward growth of a riverbank due to sedimentation?

The term for the outward growth of a riverbank due to sedimentation is accretion. This process occurs when sediment carried by water settles in areas of lower energy, typically along riverbanks and floodplains. Over time, the accumulation of sediment increases the land area along the river, a natural phenomenon that shapes river systems and surrounding ecosystems.

Accretion is important for maintaining and enhancing habitats, as well as for protecting riverbanks from erosion. It contrasts with other processes related to sediment movement and land formation, such as aggradation, which refers to the building up of land in general by the deposition of sediment over time but is not specifically tied to the outward growth of a riverbank. Avulsion refers to a sudden change in a river's course, and alluvion often pertains to newly formed land or soil deposited by a river but is not commonly used to describe the continuous growth of riverbanks. Thus, accretion is the most precise term for the process described in the question.