River

Question 1

Formation of waterfall

Answer 1

formation of waterfalls
•1. a layer of more resistant rock is exposed across the bed of a river channel
•2. differential erosion occurs, the more resistant rock is undercut by softer rock underneath
•3. the harder rock collapses into it’s plunge pool due to the abrasion and hydraulic action
•the process is repeated
•4. the repeat results the waterfall retreating back up it’s valley, it leaves a narrow, steep sided valley below the waterfall called a gorge
•this results in the waterfall becoming smaller leaving a steeping section which just produces rapid

Question 2

Formation of potholes

Answer 2

formation of potholes
•1. a weakness or crack or fault line is exposed
•2. differential erosion takes place, as abrasion and hydraulic action erodes the fault
•3. this produces a pothole
•4. the potholes enlarge until they begin to merge with one another
•5. eventually, the whole river bed is lowered due to vertical erosion of abrasion and action

Question 3

Formation of meanders

Answer 3

The bends on rivers are called meanders
•they are formed by erosion on the outer bend and deposition on the inner bend as water flows fastest on the outside due to less friction and more depth
•the river cliff is repeatedly undercut by erosion and collapses and has large sediment size whilst the slip off slope is shallower with smaller sediment size and alluvium

Question 4

Formation of oxbow lake

Answer 4

the meander will develop and enlarge as the outside bank erodes
•2. the neck becomes narrower and eventually breaks, usually from floods due to energy
•3. the oxbow lake becomes slower, increasing deposition and the meander is cut off during high flow
•4. the oxbow lake is sealed off by deposition on both sides of the channel and the oxbow lake evaporates, leaving behind a scar

Question 5

Formation of delta

Answer 5

Deltas are formed at the end of rivers (river mouth) as it flows into the sea
Rivers carry a lot of sediment (mud)
The river flows into a calm sea
This slows the river down
Which makes the river drop its sediment
This deposited sediment builds up over years creating a delta
The river is forced to split up
The smaller rivers made by deltas are called distributaries
Examples of Deltas are Nile Delta, Ganges Delta

Question 6

Formation of flood plains

Answer 6

formation of floodplains
•the meander erodes sideways as it travels downstream
•when the river overflows, it deposits alluvium
•the build up of this flooding creates the floor of the floodplain

Question 7

Formation of levees

Answer 7

levees are formed when a river floods because as the water overflows the channel, it slows
down therefore more of the load, and a coarser part is deposited close to the channel,
making the banks higher
•during normal flows, the river deposits on the bed, making it higher than the plain

Question 8

Opportunities of a delta or floodplain

Answer 8

transport: they are large routes, providing communication
•food: are sources of food with fish, growing crops and fertile soil
•water: provide fresh water
•land: they provide large opportunities for construction of houses or industry (flat land)
•tourism: fishing, kayaking and perhaps other activities
•irrigation: provides pipe water, pumping gas to farms

      •power: force means HEP powered by dams

Question 9

Define levees

Answer 9

Naturally raised river banks formed in the lower course

Question 10

Define flood plain

Answer 10

Broad flat areas of valley floor in the middle + lower course at the river

Question 11

Define Estuary

Answer 11

Coastal environment where fresh water and ocean water meet and mix

Question 12

Define delta

Answer 12

Sedimentary deposit at mouth of river that causes coastline to protrude into the ocean

Question 13

Causes of flooding

Answer 13

heavy rain - needed to cause most floods, increasing likelihood
•snow melting - rapid increase in water levels
•steep slopes - gathers water into one area
•ploughing (in straight lines) - surface runoff is faster
•impermeable rock - the land is left to surface runoff and more absorption
•urbanisation - fast drainage means more water quicker in an area
•deforestation - no water intercepted or absorbed by plants
•hot, dry wether - impermeable soil

Question 14

Hazard of river

Answer 14

• flooding
  * economic: •cost of cleaning; damaged buildings; loss of stock; cost of insurance
  * social: •use of services; cleaning; unemployment; death; lack of transportation
  * environmental: •ruined habitats; destroys trees; ruins farmland; disease; littering

                 * short term: •road covered; evacuation; minor injury
                 * long term: •property damage; death; major stock damage; costs; disease