Rivers
- Created by: lucy
- Created on: 04-01-13 14:08
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- Rivers
- Drainage basin hydrological system
- Inputs
- stages
- outputs
- Water balance
- Bradshaw model
- Drainage basin patterns
- rectanguler
- Parallel
- Radial
- Dendritic
- trellised
- morphometry of basins
- water budget/balance
- Hydrographs
- River discharge
- rock type
- temperature
- soil type
- basin characteristics
- precipitation
- vegetation
- amount of water already in river
- River discharge
- Hjulstrom curves
- channel processes
- Transport
- suspension
- very fine material is carried in the water - most material carried this way
- solution
- substances that can dissolve are carried in water
- saltation
- larger particles are too heavy to be carried in suspension, instead bounced on river bed
- Traction
- very large particles are pushed along bed of river by force of water
- suspension
- Erosion
- Hydraulic action
- the pressure of water breaks rock particles away from bed and banks, strongest in rapids, waterfalls and during floods
- Solution
- dissolving of rock by chemical processes
- lateral erosion
- Attrition
- eroded rocks smash into each other into smaller fragments, doesn't erode bed/banks
- vertical erosion
- Corrasion
- eroded pieces of rock scrape against the bed and banks removing material, most erosion happens via this
- Hydraulic action
- deposition
- Transport
- wetted perimeter
- Hydraulic radius
- mannings equation
- Graded long profile
- cross profile
- Long profile
- graded profile
- Landforms of erosion and deposition
- erosion
- Rapids
- several sections of hard rock that create turbulent water
- Waterfalls
- from where a band of hard rock meets soft rock, soft rock is eroded leaving a step of hard rock. Water flowing over step speeds up due to lack of friction so gives water greater erosive power = more undercutting of harder rock which can collapse which causes a plunge pool cut out via abrasion to be formed this leads to it retreating and leaving beund a gorge.
- Potholes
- small circular hollows in the river bed that are formed by abrasion (corrasion)
- meanders
- deposition
- Levees
- formed when a river overflows its banks, material is deposited across whole flood plain as river looses velocity - heaviest first closest to river channel = levee
- Deltas
- Braiding
- occurs when rivers carry large amount of eroded sediment. If velocity drops or sediment = to large, deposited on channel, causes river to divide into small winding channels that soon join back into one.
- Flood plains
- Levees
- alternating pools and riffles develop at equally spaced intervals which are 5-6 times the width of river bed. Deeper in pools so more efficient = higher erosive power. spacing between riffles and pools causes max flow to be on one side so turbulence increases = helicoidal flow.
- deposition
- Rejuvination
- vertical erosion
- Rapids
- deposition
- Levees
- formed when a river overflows its banks, material is deposited across whole flood plain as river looses velocity - heaviest first closest to river channel = levee
- Deltas
- Braiding
- occurs when rivers carry large amount of eroded sediment. If velocity drops or sediment = to large, deposited on channel, causes river to divide into small winding channels that soon join back into one.
- Flood plains
- Levees
- erosion
- Causes and impacts of flooding
- Human factors
- flood management strategies
- Flood management strategies
- soft engineering
- river restoration
- Wetland and river bank consevation
- river quaggy
- alteration of urban areas
- Land use management
- Abingdon, UK
- built on flood plains where 1500 houses = 1% chance of flooding each year.
- intense storms - July 2007 where river thames and ock burst banks and 600 properties flooded
- hard engineering schemes were rejected as they were too expensive
- intense storms - July 2007 where river thames and ock burst banks and 600 properties flooded
- built on flood plains where 1500 houses = 1% chance of flooding each year.
- Abingdon, UK
- weather forecasts and flood warnings
- Hollistic
- Soakways
- Abingdon, UK
- built on flood plains where 1500 houses = 1% chance of flooding each year.
- intense storms - July 2007 where river thames and ock burst banks and 600 properties flooded
- hard engineering schemes were rejected as they were too expensive
- intense storms - July 2007 where river thames and ock burst banks and 600 properties flooded
- built on flood plains where 1500 houses = 1% chance of flooding each year.
- Abingdon, UK
- hard engineering
- Levees
- channel straightening
- diversion spillways
- Dams
- Yangtze river - china
- Levees
- flows through china and is 6380 km long, 3rd largest river in the world
- 1954 flood covered 193, 000 km2 worth of land, killed 33,169 people and 18 million people had to move.
- Pros
- produces lots of electricity - 22.5 gigawatts = 3% of chinas demand
- reduced risk from once every 10 yrs to once every 100 years
- reduction of flooding - safer to navigate and river shipping has increased
- cons
- destroy habitats and endanger species
- dam will trap sediment which could lead to failure of dam and more flooding
- dam doesnt protect everyone and increase flooding in tributaries therefore more erosion of riverbanks = collapses and landslides
- will flood farmland, 657 factories, 1300 cultural and historic interest.
- 1.3 - 2million people wil have to relocate and 13 cities and 1352 villages = submerges
- Yangtze river - china
- soft engineering
- Flood management strategies
- agriculture
- deforestation
- climate change
- urbanisation
- flood management strategies
- Physical factors
- high drainage density
- steep slopes
- circular drainage basins
- sparse vegetation or deciduous trees
- impermeable ground
- Impacts
- Economic
- Social
- Environmental
- Carlisle, Cumbria 2005
- South Asia 2007
- Human factors
- Flood management strategies
- soft engineering
- river restoration
- Wetland and river bank consevation
- river quaggy
- alteration of urban areas
- Land use management
- weather forecasts and flood warnings
- Hollistic
- Soakways
- hard engineering
- channel straightening
- diversion spillways
- Dams
- Yangtze river - china
- flows through china and is 6380 km long, 3rd largest river in the world
- 1954 flood covered 193, 000 km2 worth of land, killed 33,169 people and 18 million people had to move.
- Pros
- produces lots of electricity - 22.5 gigawatts = 3% of chinas demand
- reduced risk from once every 10 yrs to once every 100 years
- reduction of flooding - safer to navigate and river shipping has increased
- cons
- destroy habitats and endanger species
- dam will trap sediment which could lead to failure of dam and more flooding
- dam doesnt protect everyone and increase flooding in tributaries therefore more erosion of riverbanks = collapses and landslides
- will flood farmland, 657 factories, 1300 cultural and historic interest.
- 1.3 - 2million people wil have to relocate and 13 cities and 1352 villages = submerges
- flows through china and is 6380 km long, 3rd largest river in the world
- Yangtze river - china
- soft engineering
- Drainage basin hydrological system
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