river landscapes Flashcards
hydraullic action
-force of water wearing down rock
abrasion
-sediment/rock grinding down material along the river bed as it moves
attrition
-rocks collide with eachother, causing them to break apart
upper course characteristics
-cold and wet climate
-v shaped valleys
-fast flowing, high carrying capacity, flows downhill
-narrow
-shallow
-high erosion, high hydraullic action
-large jagged rocks, rocks havent been in river long enough
-waterfalls
middle course characteristics
-meanders
-ox bow lakes
-flood plains
-levees
-small villages
-farms
-wide
-flood plains
-rounded off pebbles, due to hydraullic action
-deep, abrasion against river bed
lower course characteristics
-lots of human activity
-deltas
-fine sediment deposition
-slow flowing
-flood plain
how are v shaped valleys
1)hydraullic action and abrasion, river erodes downwards
2)the steep sides are attacked by weathering, this breaks up and loosens the soil and rock
3)loosned material collapses beacuse of gravity, and washed into the river by rain water
formation of a waterfall
1) fast flowing water in upper course meets a different in rock type\
2) softer secondary rock is eroded faster, creating a plunge pool, falling water and boulders wear away the softer rock
3)hard rock above is undercut
4)hard rock collapses into the plunge pool, position of the water fall moves back leaving behind a gorge, moves it way upstream
formation of a pothole:
-fast flowing water
-water and rocks get swept into circular motions around the river bed
-continued abrasion against the river bed deepens and enlargens the pothole
formation of a meander
faster flowing water on the outside, causing erosion. River flows slower on inside, deposition takes place, narrowing the river. Continued arosion bends meander more
deltas
slow flowing river causes river to split into distubutaries, due to less hydraullic action, creating islands of sediment (deposition)
causes of river flooding
-flood plains
-increased urbanizations, infiltartion
-intense rainfall
-prolonged rainfall
-geoglogy, permaeble rocks allow water to flow throw pores and cracks, impermaeble rocks do not
-deforestation, increase surface run off
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impact of flooding on property
-permanent structureal damage
-water intrusion
-damages rooftops
-cracks in foundation
-fraged electrical wiring
impact of flooding on transport
-roads closed, increased traffic congestion, traffic delays, diverting routes
-damage of transport networks
-coastal airport damage
-safety risks, increased road accidents
impact of flooding on business/economy
-lost productivity
-economic activity slows down
-resource inflow slows
