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Top curves

By Water

Around the world, moving water picks up and transports millions of tonnes of sediment every day, along rivers, coasts, and even in the deep oceans.
Erosion by water diagram Sediment, whether picked up by flowing water or by waves, is moved along in one of four ways:
  1. Traction is the rolling or dragging of large grains along a river bed or shore, aided by the push of the smaller grains (below).
  2. Saltation is the bouncing of sand grains as they are picked up, carried along, and dropped repeatedly by flowing water. 
  3. Fine particles (silt and clay) are carried in Suspension in the water – they will only settle out if the water is still. 
  4. Soluble salts are carried in Solution in the water – the sea is obviously salty, but rivers contain dissolved salts, too.
The bed load of a river (pebbles and sand grains) helps to erode the river bed and banks by abrasion, especially when the river is in flood. In a similar way, waves cause cliffs to erode especially during storms. As the pebbles and sand grind away the river bed or sea shore, they also become smaller and more rounded, a process called attrition.

Erosion & Transport by Rivers

Sediment transport by water animation


Erosion & Transport in the Sea

Bottom curves