A meander is a large bend in a river which forms on the gentler slopes of the middle course. Rivers flow fastest on the outside of a river bend so erode the base of the bank mainly by hydraulic action but also by corrasion (lateral erosion) as the river will have more load in it. Over time the base of the bank is eroded so much that the bank becomes unsupported and collapses, leaving behind a steep sided river cliff. The rivers slowest flow is therefore on the inside of the meander where river load is deposited due to its lack of energy making it unable to carry the material along with it. This is called a river beach.
Braiding is when the river splits up into channels as a result of the deposition of alluvium in small areas across the width of the river. This happens when the river slows very quickly, losing energy and therefore deposition happens. Where deposits of alluvium break the surface of the water, islands develop which forces the river to flow in channels.
Erosion happens on the outside of every part of the meander. As a result the end of the river bend starts to erode towards the beginning. This leads to a narrowing of the neck between them. During times of flood the neck may be broken through and as rivers follow the path of least resistance it will flow straight through the neck, bypassing the meander completely. As the fastest flow in a straight river is in the centre, deposition occurs at the banks which cut off the old meander to form an ox-bow lake. The water in the ox-bow lake will eventually evaporate and be colonised by vegetation.
In times of flood a river may overflow its banks and spread over the flood plain. As it does so it loses energy and deposits its material across the flood plain. As it takes more energy to carry larger particles, these are deposited first and therefore build up along the banks of the river to form a natural embankment which are called levees. The levee will become higher every time the river floods.
The flood plain of a river is the large area of flat land either side of the river over which it deposits alluvium (silt and sand) each time it floods. Larger particles are deposited closest to the river and the smallest particles further away.
- Water Supply
- Dams have been placed across fast flowing rivers in the upper course where V-shape valleys are easy to dam and high rainfall means lots of water
- Sightseeing, e.g. waterfalls
- Gorge walking
- Fishing, e.g. salmon
- Gentler slopes and good access to both lower and upper course features means lots of tourists stay here in B&Bs (often provided by farmers) and caravan and camp sites
- Mainly hill sheep farming due to poor soils, steep slopes, cold weather, high rainfall and exposed hillsides
- A mixture of dairy and arable farming as slopes are gentler and weather is improving
- Deep fertile soils on the flood plain of the river allow crops to be grown
- Weather is much better so allows crops to ripen before harvest
- Much flatter land allows machinery to be used
- On the slopes of the upper course where farming does not occur, commercial forestry takes place as conifers can grow in the unsuitable conditions
- In the upper course Hydro Electric Power (HEP) takes place in an area of high rainfall and fast flowing water
- On the flat land of the flood plain close to the sea, heavy industry such as iron and steel works locate due to the large amount of flat land required, e.g. River Tees
- Raw materials can be transported to factories by river, e.g. oil to Grangemouth oil refinery on the River Forth
- The wide, deep river close to the sea is ideal for transport of large boats such as oil tankers
- Roads and railways follow the course of a river closely as it provides flat land even in areas of higher and steeper land
Conflicts on rivers tend to be:
- Cars etc blocking access points to the river
- Angling on the river being disturbed by other users, e.g. kayaking
- Litter left by tourists especially campers
- Narrow roads and high volumes of traffic leads to traffic congestion
- Dumping of warm waste water by industry into rivers and oil/petrol from large ships getting into the water and causing pollution and damage to marine habitats