Flussarm

Flussarm is a term used in geomorphology and hydrology to describe a secondary channel of a river that diverges from the main stem and may later rejoin it, or terminate in a backwater or floodplain. In German-speaking contexts, the word literally means “river arm” and is commonly applied to distributary channels in deltas as well as to persistent side channels within inland floodplains.

Formation and characteristics

Flussarms arise through processes of sediment deposition, natural levee development, and shifting flow during floods. Sediment may cause the main channel to split, creating parallel or braided branches. Over time, avulsion or channel closure can leave an arm as a relict channel, a restored wetland, or a permanently flowing side arm. The flow regime of a Flussarm is typically influenced by seasonal discharge, flood events, and human alterations to the landscape.

Types and settings

In deltaic settings, distributary arms transport water and sediment away from the main river and contribute to delta growth and complexity. In inland floodplains, non-tidal arms often connect to backwaters and wetlands, providing habitat diversity. Tidal rivers may host estuarine arms where freshwater mixes with seawater, creating brackish conditions.

Ecology and use

Flussarms support specialized plant communities and serve as important habitats for fish, amphibians, and invertebrates. They also influence nutrient cycling and sediment deposition across the floodplain. Human uses include drainage, irrigation, water supply, and, in some cases, navigation. Restoration projects may aim to reconnect arms with the main channel to enhance ecology and floodplain functions.

See also

River delta, meander, oxbow lake, backwater, distributary, estuary, floodplain.