Which process involves the sedimentation of materials in still water at the mouth of a river?

The process that involves the sedimentation of materials in still water at the mouth of a river is coastal deposition. This occurs when the river carries sediments, which can include sand, silt, and clay, and as the river reaches the still waters of a larger body of water, such as an ocean or lake, the energy of the water decreases. This reduction in energy allows the sediment to settle and accumulate, forming features like deltas or sandbanks at the mouth of the river.

In contrast, coastal erosion pertains to the wearing away of land and the removal of beach or coastal materials due to wave action, which does not involve the accumulation of sediments. River meandering describes the winding curves and bends of a river over its course, rather than sediment deposition. Beach nourishment refers to the process of adding sand or sediment to a beach to combat erosion and enhance its width, which is not specific to river mouths but rather to coastal management practices. Thus, the correct answer, coastal deposition, focuses specifically on the settling of sediments at the river’s mouth, characterizing a natural sedimentary process in that environment.