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50 Cards in this Set
- Front
- Back
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Bradshaw’s model |
-At upper course it is SMALLER and gets LARGER: river discharge; channel width; channel depth; velocity -At the upper course it is LARGER and gets SMALLER: sediment particle size; channel bed roughness; slope angle |
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What is the source |
Where the stream starts |
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Tributary |
A river or stream flowing into a larger river |
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Confluence |
The junction of two rivers |
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Drainage basin |
The area of land drained by a river |
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Watershed |
A ridge that separates water flowing into different rivers. |
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Main river channel |
The largest watercourse draining water from the drainage basin |
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Mouth |
Where the river ends- may flow into a reservoir, estuary or delta |
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How does rock type affect river |
Resistant rock- at rivers upper course as forms high land. River channels small as low velocity and sediment load volume: clear river. Less residant rock- at rivers lower course. Large river channel as high velocity and erosive power. |
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Rocks and stones bang together = |
Attrition |
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Sands and stone scrape the bed and banks= |
Abrasion |
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Fast flowing water washes the bank away= |
Hydraulic action |
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Some minerals dissolve in river water= |
Solution Only happens if carbon based rocks |
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Suspension |
Fine light material is carried along by the river |
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Traction |
Large boulders and rocks are rolled along the river bed |
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Solution |
Minerals are dissolver in the water, this is a chemical change |
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Saltation |
Small pebbles and stones are bounced along the river bed |
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Upper course: How water falls are formed (buckden beck) |
- river travels across a bed of more resistant rock - erosion of the LR (less resistant) rock continues under R rock. -rivers energy creates plunge pool at bottom -the LR is eroded so much by abrasion and hydraulic rock that it creates a ledge and collapses - waterfall takes new position, leaving a steep valley or gorge |
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V shaped valley features: |
-there is resistant rock -the valley sides are steep and narrow at the bottom - interlocking Spurs |
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Weathering in the sides of a river |
Biological- Roots grow in cracks and break rocks off Physical- Freeze thaw Chemical- Rain can mix with atmospheric gases and for acid rain. This can dissolve rock |
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Middle course: Flood plain formation |
Lateral erosion on meanders, forms wide and flat areas |
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Middle course: Formation of meanders |
1) helicoidal flow means the thalweg (fastest current) moves laterally 2) the fastest flow is directed towards the inside of the bend; undercuts bank causing a river cliff 3) flow is slower on outside so sediment builds up causing a slip-off slope |
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middle course: Oxbow lake formation |
River current erodes bank until meander bend meets. River flows straight through and land dries up an dorms and oxbow lake |
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middle course (flood plains): Formation of natural levées |
Sediment deposited on top of river banks during floods, acts as a wall |
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Lower course: Formation of deltas |
River approaches the sea, hydraulic radius decreases and deposition happens. This causes bars of sediment in the river channel. River splits into distributaries. Sediment build the delta out to sea. |
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What will affect a storm hydrograph? |
-precipitation -geology (rock type) -drainage basin and shape -soil -towns/cities |
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Upper course: V shaped valley features: |
-there is resistant rock -the valley sides are steep and narrow at the bottom - interlocking Spurs |
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CASE STUDY- Sheffield: what is the significance of its location in making it vulnerable to flooding |
- at east of valley there is a floodplain, full of housing and impermeable surfaces -soil drain slowly-> water will run of hills that surround and go into city -city surrounded by pennine hills. Are steep so not much lag time -lots of tributaires so flood grow fast |
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CASE STUDY- Sheffield: How did the interaction of physical and human processes lead to the Sheffield floods in 2007? |
- covered with lots of impermeable surfaces and relays on drains -Drains could not cope with rainfall and became blocked -This caused roads and railways to be blocked - Had already had lots of rainfall so soil was already saturated -23 upstream reservoirs but theses overflowed due to volume -Flashy nature of river catchment makes flood management important but difficult |
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CASE STUDY- Somerset levels: What land change had made the Somerset levels more vulnerable? |
Ejs |
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CASE STUDY- Somerset levels: What land change had made the Somerset levels more vulnerable? |
-artificially drained in 17 century using ditches - this affects natural drainage systems e.g. infiltration |
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CASE STUDY- Somerset levels: What land change had made the Somerset levels more vulnerable? |
-artificially drained in 17 century using ditches - this affects natural drainage systems e.g. infiltration |
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CASE STUDY- Somerset levels: What changes to human and physical factors are leading to an increased flood risk? |
PHYSICAL- depending on wind direction, it drives low air pressure with lots of rain HUMAN - Levées and ditches have been added - these interference with natural systems and can make problem worse—— by making river bed higher, river just adjusts to new channel banks |
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CASE STUDY- Somerset levels: What other flooding threats will climate change bring in the future? |
- greater storminess with damaging winds -higher, longer lasting floods -higher spring tides -more storm surges |
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Catchment plans: In rural parts of the catchment |
Work with landowners to reduce runoff and improved land use |
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Catchment plans: In rural parts of the catchment |
Work with landowners to reduce runoff, improving land use and restoring flood plans to natural state |
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Catchment plans: In the middle and lower catchment |
Prevent unsuitable development on flood plains |
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Catchment plans: In the middle and lower catchment |
Prevent unsuitable development on flood plains |
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Catchment plans: In urban areas |
Reduce surface water run off, improve flood defences and encourage owners to protect vulnerable buildings |
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Catchment plans: Where few people are at risk from flooding |
Work with natural flood processes |
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Flood risk management (hard engineering): Flood walls |
BENEFITS -fairly cheap -useful for city centres where limited space COSTS -increase flood risks downstream |
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Flood risk management (hard engineering) : Constructed Levées |
BENEFITS - allow people to live besides river without fearing floodings COSTS -increase flood risk downstream -can fail; water rises over them; slumping; erosion -expensive |
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Flood risk management (hard engineering) : Dredging |
BENEFITS -provides a larger channel for water to fill COSTS -needs to be done every year -flood risks down stream - expensive: £50,00 |
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Flood risk management (hard engineering) : Flood relief channel |
BENEFITS -protects built up areas - Allows people to live near rivers without fearing floods COSTS - cause flooding elsewhere -expensive |
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Flood risk management (hard engineering) : Flood relief channel |
BENEFITS -protects built up areas - Allows people to live near rivers without fearing floods COSTS - cause flooding elsewhere -expensive |
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Flood risk management (soft engineering) : Flood plain retention |
BENEFITS - increased ability to store flood water - worked in Darlington 2007 COSTS -land cannot be developed- not nescassairly bad -£1.2 million for 2km |
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Flood risk management (hard engineering) : Flood relief channel |
BENEFITS -protects built up areas - Allows people to live near rivers without fearing floods COSTS - cause flooding elsewhere -expensive |
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Flood risk management (soft engineering) : Flood plain retention |
returns flood plain to natural state BENEFITS - increased ability to store flood water - worked in Darlington 2007 COSTS -land cannot be developed- not nescassairly bad -£1.2 million for 2km |
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Flood risk management (soft engineering) : river channel restoration |
returns river it natural state BENEFITS -improves ecology: 30% increase in wildlife -People like natural look COSTS -Land cannot be developed- not n’essacairly bad -£1.2 million for 2km |
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How to measure river discharge |
Area x velocity Measured in cumecs |
