UPPER COURSE: steep sides narrow and shallow.(VE) MIDDLE COURSE: gently sloping sides, wider and deeper. (LE) LOWER COURSE: very wide/ flat sides, very, deep channel. (LE)
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Processes of erosion.
HYDRAULIC ACTION: force of water. ABRASION: bed load hits the river beeds and banks. ATTRITION: bed loads hit eachother. SOLUTION: river dissolves rock e.g. limestone/chalk
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Processes of transportation
TRACTION: large particle rolled along river bed. SALTATION: pebbles bounced along river bed. SUSPENSION: light materials carried by water. SOLUTION: so;luble materials carried away.
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Why does deposition occur?
volume of wster decreases (shallow), decrease in speed, more deposition being carried, sheltered area e.g. bay, river reackes the mouth.
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Describe a meander
OUTSIDE BEND: faster flow, deeper, erosion and river clif formed. INSIDE BEND: slower, shallow, deposition and a slip off slope formed.
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How are ox-bow lakes fromed?
erosions makes the outside bends grow closer, the river breaks through the neck during a flood, river flows the fastest route, deposition cuts off meander.
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How is a waterfall formed?
1.waterfalls forms over area of hard and soft rock. 2 .softer rock eroded more 3. steep drop creted called a waterfall 4. hardrock is undercut by erosion and collapses 5. collapsed rocks create abbrasion plunhge pool 6. waterfall retreates - gorge
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What happens when a river floods?
rivers flood on flood plains. it creates leeves when heaveer material is dropped first as the water loses energy.
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what does a hydrography show?
it shopw rainfall and river disharge. (rising limb and falling limb)
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what is lag time?
the delay in time between peak rainfall and peak dicharge. lag time occurs because not all rainfall lands in the river. longer lag time = less risk of flooding
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what affects river discharge?
heavylong periods of rain (saturation),steep relief urbanisation (drains), deforestation( no interception), temperature (evaportation, hard surafce) snow melt, impermeable surfaces/ rocks.
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Give TWO examples of soft flood management.
channel straightening (it moves water away quickly but can flood downstream and more erosion occurs) Dams and resvoirs (stores water for drinking and HEP but floods existing areas, expensive, no depositions downstream - less fertile farmland)
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Give TWO examples of hard flood managemant.
flood warnings ( impact is reduced, more time for evacuation but doesn't stop flood and some people may not hear it) Flood plain zoning (no impermeable surfaces, no damaged homes/buildings but limits areas to build and doesn't help area built before
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What is water deficit and how can it be resolved?
when there is a greter supply than demand. it can be resolved by reducing amount of wter used, fixing leaky pipes and building dams and resevoir.
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Other cards in this set
Card 2
Front
Processes of erosion.
Back
HYDRAULIC ACTION: force of water. ABRASION: bed load hits the river beeds and banks. ATTRITION: bed loads hit eachother. SOLUTION: river dissolves rock e.g. limestone/chalk
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