How does rainfall contribute sediment to coastal environments?

Rainfall is a critical factor in the development of coastal landforms because it facilitates the production and transport of sediment to the coast. It contributes to this process primarily by generating runoff that forms streams, which act as conduits for moving material from inland areas toward the shoreline.1

The volume and type of sediment delivered to the coast are heavily influenced by the local climate, creating distinct differences between environments such as tropical regions and deserts. Once this sediment reaches the river mouth, its further distribution is governed by the river's discharge and velocity. Under normal conditions, sediment is transported within the channel, but during periods of high rainfall and flooding, suspended sediment and organic matter are dispersed into interfluve areas, contributing to the growth and aggradation of deltaic plains. Ultimately, the balance between this river-derived sediment supply and marine processes determines the morphology of coastal features like deltas and estuaries.123