siltning

Siltning, or siltation, is the process by which fine sediment, especially silt, accumulates in a water body, reducing depth and altering flow. It is common in rivers, lakes, reservoirs, harbors and coastal zones where suspended sediments settle as flow velocity drops.

Sediment supply comes from natural erosion in the watershed and from human activities such as agriculture, deforestation, mining and construction. Dams and reservoirs trap sediment, increasing siltation downstream, while channel modifications and dredging can modify the pattern of accumulation.

The deposited material forms beds of fine particles and can create shoals or deltas. Siltning decreases navigable depth, raises flood risk upstream, increases maintenance costs for dredging and harbor operations, and alters aquatic habitats by increasing turbidity and changing substrate conditions for plants and animals.

Impacts on water quality and ecosystem function can include reduced oxygen levels and shifts in species composition. In enclosed waters, sediment-associated nutrients can contribute to eutrophication and periodic algal blooms.

Management focuses on reducing sediment supply and removing accumulated material. Strategies include soil conservation and reforestation in the watershed, erosion controls, sediment bypassing or realimentation in rivers, dredging and proper disposal of dredged material, and ecological restoration such as wetlands creation to trap sediments. Monitoring methods commonly involve bathymetric surveys, sediment yield measurements, and remote sensing to estimate deposition rates and inform dredging schedules.