Water on the Land
- Created by: Molly6098
- Created on: 16-11-13 14:05
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- Water on the Land
- River Valley
- Middle Course
- Medium gradient, gently sloping valley sides, wider, deeper channel
- Upper Course
- Steep, V-shaped valley, steep sides, narrow, shallow channel
- Lower Course
- Gentle gradient, very wide, almost flat valley, very wide deep channel
- Profiles
- Cross Profile: shows what the cross section looks like
- Long Profile:shows how the gradient changes
- Erosion
- Vertical erosion: deepens channel, dominant in upper course
- Lateral erosion: widens channel, dominant in middle and lower courses
- Middle Course
- Erosion, Transportation, Depositation
- Transportation
- Suspension
- Small particles carried along by water
- Saltaion
- Pebble sized particles bounced along river bed by force of water
- Solution
- Materials dissolve in water and are carried along
- Traction
- Large particles pushed along river bed by force of water
- Suspension
- Erosion
- Attrition
- Eroded rocks smash into each other and break into smaller pieces with rounded edges
- Abrasion
- Eroded rocks scrape against channel, wearing it away-most erosion happens like this
- Solution
- River dissolves some types of rock
- Hydraulic action
- Force of water breaks rock particles away from river channel
- Attrition
- Deposition
- Rivers drops material when it slows down
- Water is shallower
- Amount of eroded material increases
- River reaches the mouth
- Volume of water falls
- Rivers drops material when it slows down
- Transportation
- River Landforms
- Waterfalls and Gorges
- Form where a river flows over hard rock then soft rock.Soft rock erodes creating a step. Steep drop eventually forms (waterfall). Hard rock becomes undercut and collapses. Collapsed rocks swirled around at bottom and erode rock creating a deep plunge pool.
- Over time more undercutting makes waterfall move backwards creating a gorge
- Ox-Bow Lakes
- Formed by meanders
- Erosion causes outer bends to get closer, leaving a small bit of land (neck). River breaks through land, river flows along shortest course. Deposition cuts of meander leaving ox-bow lake
- Flood Plains and Levees
- Levees
- Natural embankments along edges of river channel. Created when river floods and heaviest material deposited first.
- Flood plains
- Wide valley floor that occasionally gets flooded. when river floods it deposits, building up flood plain. Meanders migrate making it wider. Slip off slopes also build it up.
- Levees
- Meanders
- Middle and lower courses
- Current is faster on the outside of the bend-river channel is deeper, more erosion takes place causing river cliffs. Current is slower on inside of bend-shallower, eroded material is deposited forming slip-off slopes
- Waterfalls and Gorges
- River Discharge
- Factors
- Hot, dry or cold, freezing conditions make ground hard=increases runoff, decreases lag time, increases discharge
- Urban areas covered in impermeable materials=more runoff, shorter lag time, increased discharge
- Impermeable rock=more runoff, shorter lag time, more discharge
- Saturated soil=more runoff, shorter lag time, more discharge
- Steep slope=shorter lag time, increased discharge
- More rain and short heavy periods of rainfall=more runoff, shorter lag time, more discharge
- Words
- Rising Limb: Increase in river discharge
- Lag time: delay between peak rainfall and peak discharge
- Falling limb: decrease in river discharge
- Hydrographs
- Flashy
- Natural river
- Lack of vegetation
- High levels of precipitation
- Intense rainfall
- Steep valley sides
- Saturated soils
- Cold conditions
- Impermeable rock
- High drainage density
- Urban areas
- Subdued
- Low valley sides
- Gentle, steady rainfall
- Low levels of precipitation
- Lots of vegetation
- Hot conditions
- Permeable surfaces
- Low drainage density
- Flashy
- Factors
- Flooding
- Case Study
- Poor
- Effects
- Secondary
- 100,000 people caught water borne diseases
- Children lost education-4000 schools affected
- Floods reduced basmati rice yields-prices rose 10%
- Farmers and factory workers became unemployed
- Primary
- Factories closed, livestock killed, rivers polluted
- 44 schools and 112, 000 houses and 10,000km road destroyed
- Over 2000 dead, 25 million homeless
- Secondary
- Causes
- Melting snow from Himalayas
- Heavy Rainfall-900 mm in July
- Peak discharge of both rivers happened at once which increased discharge down stream
- Responses
- Secondary
- Some homes rebuilt on stilts
- International charities funded rebuilding homes, agriculture and fishing industries
- Primary
- Other governments and international charities sent food, water, medical aid and technical equipment
- No evacuations-blocked transport links slowed any attempts
- Secondary
- About
- July and August 2007
- South Asia (Bangladesh, India
- Brahmaputra and Ganges
- Effects
- Rich
- Effects
- Primary
- 70000 addresses lost power
- 4 schools flooded, 350 businesses shut
- Roads and bridges damaged
- 3 dead, 3000 homeless
- Rivers polluted
- Secondary
- Stress related illnesses increased
- Children lost education
- 3000 jobs at risk
- Primary
- Causes
- Large urban area-increased run-off
- 200 mm of rain in 36 hours-saturated soil, increased run-off
- Caused discharge to reach 1520 Cumecs (usually 52)
- Responses
- Secondary
- Flood defence scheme set up
- Community groups set up to provide support
- Primary
- Centres provided food and drink
- People evacuated
- Temporary accommodation set up
- Secondary
- About
- 8th January, 2005
- Carlisle, England
- River Eden
- Effects
- Poor
- Causes
- Physical (climatic)
- Low evapotranspiration
- Coastal storms
- Human Factors
- Dam bursting-sudden rush of water
- Poor artificial levee construction-Give way=big rush of water
- Government corruption-cheap labour
- Farming-Soil compaction=less porous
- Global warming-creates more extreme weather
- Channelisation-Artificially straightened
- Physical (drainage basin)
- Impermeable rock
- Small river basin-flash floods
- Little vegetation cover
- Saturated soils
- Physical (climatic)
- Case Study
- Hard and soft engineering
- Soft Engineering
- Flood Plain Zoning
- Benefits: risk of flooding reduced-impermeable surfaces aren't created, Impact of flooding reduced
- Restrictions prevent building on parts of flood plain likely to be affected
- Disadvantages: expansion of an urban area is limited, no help to areas already built on.
- Preparation
- Benefits: Impacts of flooding reduced. People less likely to worry
- Buildings modified to reduce damage flood could cause. People make plans in case of flooding
- Disadvantages: doesn't guarantee safety from a flood, gives false sense of security, expensive to modify buildings
- Do nothing
- Benefits: When river floods in deposits eroded material making farmland more fertile
- No money spent on preventing floods or preparing for them-flooding is a natural process
- Disadvantages: risks and impacts of flooding aren't reduced, flood will probably cause a lot of damage
- Flood Warnings
- Benefits: Impacts reduced-people more prepared
- Environment Agency warns people of floods through media
- Disadvantageds: Doesn't stop floods. Living in a place with lots of warnings makes it difficult to get insurance. People may not hear warnings
- Flood Plain Zoning
- Hard Engineering
- Channel Straightening
- Benefits: Water moves out of the area more quickly
- River's course is straightened by cutting off meanders
- Disadvantages: More chance of flooding and erosion down stream
- Dams and Resevoirs
- Benefits: Reservoirs store water which reduces risk of flooding. Stored water can be used as drinking water and for HEP
- Dams built across rivers, resevoirs form behind them
- Disadvantages: Expensive to build. Can flood existing settlements. Eroded material deposited in reservoir not on rivers natural course so farms down stream are less fertile
- Channel Straightening
- Cas Studies
- Hard engineering
- Defences
- Many levees built along river
- 3 Gorges Dam-101m high, reservoir holds 22km of water, largest HEP station in the world
- About
- 5 major floods in last century
- Seasonal flooding common
- 1947-covered 193,000 km, killed 33, 169, 18 million moved
- Yangtze, China-6380km long
- 1998-killed 3000, 14 million homeless
- Effects
- Negative
- Could destroy habitats and endanger species
- Dam traps sediment which could cause dam to burst resulting in catastrophic floods
- Dam causes water levels to rise and increases flooding on tributaries
- Farmland, 657 factories and 1300 sites of cultural and historical interest submerged
- Many levees broke adding to devastating floods in 1998
- 1.3-2 million will have to relocate-13 cities and 1352 villages submerged
- Positive
- Turbines produce enough electricity for 3% of China
- Reduced major flooding
- Made it much easier to navigate up the Yangtze
- Negative
- Defences
- Soft engineering
- Defences
- Flood wardens communicate advice and warnings
- Improvements made to riparian buffers
- Detailed advice on internet about reducing flood damage
- Planning restrictions on new builds
- Restrictions on land use
- Low-value land allowed to flood
- Local flood warning plan and 24 hour floodline
- Gravel soakways along A34
- Tesco revised extension plans
- About
- 1500 properties have 1% chance of flooding a year
- Abingdon, England on flood plains of Thames and Ock
- Regular floods over the years
- Effects
- Several flood warnings used
- Difficult to measure success
- Recent floods did less damage
- Defences
- Hard engineering
- Soft Engineering
- River Valley
- Form where a river flows over hard rock then soft rock.Soft rock erodes creating a step. Steep drop eventually forms (waterfall). Hard rock becomes undercut and collapses. Collapsed rocks swirled around at bottom and erode rock creating a deep plunge pool.
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