rivers

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  • rivers case study Bangladesh and missisippi
    • mass movement
      • soil creep (soil particles move down the slope due to gravity)
      • slumping (the river erodes the bottom of the valley making a steeper slope
      • rock fall (rocks at the top of the valley break off and move down the slope)
    • upper river landforms
      • interlocking spurs
        • they are are ridges in the valley
        • the ridges interlock
      • waterfalls
        • hard rock above soft rock
        • the soft rock i easily eroded by hydraulic action
        • a plunge pool is formed by hydraulic action and abrasion
        • overhanging hard rock eventually collapses
    • middle river landforms
      • meanders
        • caused by hydraulic action and abrasion
        • the river is eroded laterally and forms large bends
        • the inside bend has the slowest flow and the river deposits materiel here
      • ox bow lakes
        • the inside bend of the meaner has materiel deposited
        • eventually the neck of the meander bends will join together
        • that part of the river is no longer a meander and a crescent shaped feature is left behind
    • lower river landforms
      • flood plains
        • in the lower course the river carries lots of sediment
        • when the river floods the water spills over the surrounding area and deposits sediment
      • levees
        • a river floods and the sediment is deposited on the flood plain
        • the heavier materiel is dropped near the river channel due to loss of energy
        • after a number of floods levees are leftover
    • why do rivers flood
      • human
        • deforistation
        • climate change
        • urbanisation
      • phyisical
        • rainfall intensity
        • geology
        • snow melt
        • drainage basin
    • Mississippi flooding 2011 USA
      • causes
        • heavy rainfall
        • impermeable surfaces
      • impacts
        • outbreak of disease
        • homes flooded
        • nutrients washed away in soil
        • farmland destroyed
      • hard engineering management
        • levees built
        • river straightening
        • flood-ways created
      • soft engineering management
        • restoration of upland river to act as a sponge
        • government funding to farmers who use land as wildlife conservation
    • reducing impacts of flooding
      • planning
        • areas at risk are used as parks and leisure activities
      • prediction
        • environment agency monitors rivers
      • prevention
        • the environment agency says to raise height of electrical sockets , use tiles instead of carpets , install heating systems on upper floors.
      • education
        • the environment agency gives out leaflets and advertising , posts info on there website, telephone helplines and organises flood drills

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