river landscaps

Question 1

name the 6 key features of a river basin

Answer 1

source = start of the river e.g. lake or spring

drainage basin = the area drained by s river and its tributaries

watershed = area between one drainage basin ad another

tributary = small stream or river that joins a bigger one

confluence = where two rivers meet

mouth or estuary = where the river meets the sea

Question 2

characteristics of river from source to mouth

Answer 2

• steeper gradient & more friction = low flow
• narrow and shallow
• large angular sediment
• gradient is less steep = less friction
• more velocity
• wider and deeper
• rocks become rounder & load increases
• less friction is fast flow
• channel is deep and wide
• big load
• small sediment and sand

Question 3

upper course features

Answer 3

waterfalls
interlocking spurs
rapids
gorges

Question 4

middle course

Answer 4

meanders
river cliffs
slip off slope
ox bow lake

Question 5

lower course

Answer 5

flood plains

levees

Question 6

waterfalls

Answer 6

• river crosses a band of less resistant rock
• sudden drop = water fall
• softer is cut back quicker leaving an overhang over hang of harder rock
• overhang falls due to the weight of gravity and hydraulic action
• plunge pool is created
• waterfall retreats up the valley often forming gorge

Question 7

interlocking spurs

Answer 7

• created when v shaped valleys are made
• little energy for lateral erosion
• river winds and bend to avoid hard areas

Question 8

rapids

Answer 8

• ridges of hard rock = uneven slope

- e.g. in pludge pool

Question 9

meanders

Answer 9

-river channel bends
-most of water is directed to outside
- outside = greatest erosion and deepest
(can form a river cliff)
-water is faster at outside due to less friction

Question 10

slip off slope

Answer 10

formed at inside of the meander due to deposition

Question 11

oxbow lake

Answer 11

• erosion continues on the outside banks of a meander
• deposition in the inside
• ends of the meander bend come closer
• in flooding the river joins ends together
• a new straight channel is made
• old bend is cut off
• oxbow lake is made

Question 12

flood plains

Answer 12

-low flat that is flooded

Question 13

levees

Answer 13

• river drops heavy material on flood plains
• builds up close to channel
• levees are formed after floods

Question 14

human causes of flooding

Answer 14

deforestation
roots suck up water
leaves intercept with rain hitting ground

urbanisation
more surface run off because water cannot be absorbed by the ground

global climate change
increase global temperatures meaning ice melts & more storms & more rain

Question 15

natural causes to flooding

Answer 15

intense rainfall
ground is water logged = surface run off from saturation

snow melting
sea levels rise and more water in summer

impermeable rocks
granite doesn’t let water through it so water runs off into rivers and lakes so levels rise and land floods

Question 16

effects on people

Answer 16

• loss of animal and crop
• injury and death
• disease in water e.g. sewage
• loss of homes
• communication problems

Question 17

effects on environment

Answer 17

• saturation means plants cannot grow
• animals get sickness
• contamination of soil
• land slides and rotational slumping

Question 18

examples of flooding in people

Answer 18

Mozambique Africa:

• feb 2007
• homes and lives lost
• 121,000 homeless
• 12,000 livestock dead
• 16,000 chickens dead
• diaherra killed dozens from unclean water

northern uk - Lincolnshire and northwales

• 2007
• £2 billion worth of damage
• Lincolnshire = 40% of pea ruined
• wales = 40 tonnes of derbis crop and earth blocked only way out of barland 23 july

Question 19

predicting and preventing flooding

Answer 19

forecasting

• warning and evaluation maps
• computers
• rainfall reports
• monitored by environmental agency
• computer simulation e.g. texas rice uni
• texas medical centre was evacuated before large flood 2001

buildings can be redesigned
LIC buildings are on stilts

planning

• land use zoning
• selecting where to build
• nome in Alaska uses this (1flood/100years)

Question 20

define hard and soft engineering

Answer 20

hard

• controlled distribution of natural processes
• man made structures

soft

• ecological practises
• reduces erosion
• to achieve stabilisation
• to enhance habitats
• to save money

Question 21

soft engineering examples llanrwist

Answer 21

land use zoning:

• un needed land is flooded
• water drains after a few days
• temp flood barriers protect homes

Question 22

hard engineering lllanwrist

Answer 22

underground flood relief channel:

• £7million
• protects 96 homes and businesses
• divert water at times of maximum flow
• water is stored until peak flow has passed

Question 23

impacts of flooding llanwrist

Answer 23

• 31st June 2004
• heavy rain = 126 flood warnings uk
• 6days = 417.8mm of rain in capel curig
• 86 valley properties flooded

demographic
-migration away from the area

social

• communication
• travel e.g. railway closed
• loss of belonging
• no outdoor sports

environmental

• crops and animals dead
• waterlog & saturation
• debris spread along landscape

economic
£7million to help with damage
£6 million to repair railway
decreased housing value

Question 24

human causes to flooding in llanwrist

Answer 24

deforestation

• only 10% of drainage basin is covered by trees
• no roots or interception
• leads to saturation and surface run off

bridges

• reduces the amount of water flow
• leads to more water building up and flooding

channelization upstream

• more velocity
• higher risk of flooding

Question 25

physical causes of flooding

Answer 25

drainage basin = 344.5km2
rain fall = 4000mm per year

• soil is shallow and fine = waterlogged (slit and clay)
• steep gradients of drainage basin joins to betwes-y-coed before reaching narrow area where it floods
• rain drains from eastern Snowdonia mountains