Cross sectional profile of river

• The upper course of a river is characterised by:

  Steep Banks

  High Water velocity

  Narrow
• The middle course of a river is characterised by:

  Moderate width

  Moderate gradient of the river bed

  Moderate velocity
• The Lower course of the river is characterised by:

  A wide width

  Gentle Gradient of river bed and banks

  Low velocity

  High rate of deposition
• Rapids are caused when high velocity water erodes soft rocks leaving the harder rocks as outcrops causing an uneven river bed which increases turbulence.
• Meanders are formed due to the friction between the fast flowing water and the bank. The flow of water is faster near the outside bend causing more weathering and erosion than the inside bend. The inside bend loses more energy so more sediment is deposited here. This causes the outer bank to be undercut and the inner bank to be built up creating a new channel and futher bending the meander.
• Waterfalls are formed when the river flows over hard rock with a steep slope. The force of the falling water wears away the base of the cliff until eventually the weight of the rock above becomes too great and it collapses into the pool below forming a plunge pool.
• Deltas are formed where a river enters a body of still water such as a sea or lake. Here the river spreads out and divides into smaller channels. The slow moving water allows fine particles to settle out of suspension and accumulate along the delta front. These layers gradually build up to form deltas.
• Estuaries are formed at the mouth of rivers that enter the sea. They have a large volume of freshwater input from the river, but also receive saltwater from the ocean. As a result they have a unique mix of fresh and salty water. Estuaries can support a diverse range of flora and fauna including many commercially important species.
• Salt marshes are found in coastal regions where tidal waters flood the land regularly. Salt tolerant plants grow in this environment and their roots trap silt and mud. Over time this material builds up to create raised platforms called salt marsh islands. These habitats are home to a variety of wildlife including birds and insects.