Sedimenttransporten

Sediment transport, in Swedish sedimenttransporten, refers to the movement of solid material such as sand, silt, and clay by fluid flows or wind. It is a central concept in geomorphology, river engineering, and coastal dynamics, governing erosion, deposition, and channel or shoreline evolution.

The principal transport modes in water are bedload, where particles roll, slide, or saltate along the bed; and suspended load, where finer grains are carried within the water column. A dissolved load, consisting of chemical solutes, is sometimes distinguished but does not represent solid sediment transport.

Transport depends on hydraulic forcing and grain properties. Shear stress and flow velocity must often exceed thresholds for entrainment; grain size, density, porosity, and cohesion influence mobility. The Shields parameter expresses the nondimensional critical shear stress. The Exner equation describes sediment continuity, and transport rates are commonly predicted with empirical formulas such as Meyer-Peter–Müller for bedload and various suspended-load models based on velocity and turbulence, including Rouse-type profiles for concentration distribution.

Applications and implications are broad. In rivers, sediment transport shapes channels, bars, and floodplains; in coastal systems, longshore and offshore transport control beaches, dunes, and shoreline stability. Human activities, including dam construction, dredging, and land-use change, alter sediment supply, potentially causing incision, excessive deposition, or coastal retreat.

Measurement and modelling approaches combine field observations and numerical simulations. Field methods include sediment traps, turbidity sensors, and acoustic profilers to quantify transport and concentration, while models couple flow dynamics with sediment transport to simulate morphodynamic evolution over time.