What Is a Delta? Land Formed Where a River Meets a Lake or Sea

What Is a Delta? Land Formed Where a River Meets a Lake or Sea

A delta is a landform created at the mouth of a river where it enters a standing body of water—a lake, sea, or ocean. As the river's velocity drops, it deposits its sediment load (silt, sand, clay), building a fan- or triangle-shaped plain.

Key Characteristics

• Shape: Often triangular (Greek letter Δ), apex upstream.
• Distributaries: River splits into multiple channels across the delta.
• Fertility: Rich alluvial soil supports intensive agriculture (e.g., Nile, Mekong, Ganges-Brahmaputra, Mississippi deltas).
• Dynamics: Constantly changing; subsidence, sea-level rise, and human dams threaten deltas.

Size depends on sediment supply, basin subsidence, and wave/tidal energy.