Full Physical Spec

Complete full revision notes Rivers and Coasts

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Physical Geography Revision
Percolation > From soil into rocks.
Groundwater > Flow through rocks and cracks in rocks.
Infiltration > Flow from surface into soil
Throughflow > Flow along layers in soil.
Channel Catch > Rainfall from atmosphere into channel (directly).
Channel Flow > Water that flows through the river
Surface Run off/Overland Flow > Water flowing along the surface as ground is
impermeable or saturated.
Stemflow > Flow through stems and trunks
Dripflow > Flow through leaves into the ground.
Throughfall > flow through vegetation and branches.
Precipitation > flow of water from atmosphere to earths surface.
Percipitation > Flow of water from atmosphere to earths surface.
Water Balance : Runoff = Precipitation ­ Evapotranspiration + Changes in Store.
Factors Affecting A Rivers Energy:
Gradient ­ Kinetic and Potential Energy
Mass of the river/discharge.
Altitude above sea level.
Large amounts of energy is lost through internal friction. The greater the velocity
the greater the turbulence and the greater the sediment load that can be carried.
Velocity can be influenced by the channel shape in cross-section, the channel
gradient and the roughness of the channels bed and banks.
Hydraulic Radius = Cross sectional area / Wetter Perimeter
The higher the hydraulic radius the more efficient the river is.

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Valley Cross Profile
Upper Course
Steep Sides
Narrow Bottom
V Shape
Vertical Erosion
Middle Course
Wide Valley
Valley Bluffs
Flat land
Lateral Erosion
Lower Course
Wide flat floodplain
Hard to locate valley sides
Lack of erosion, higher deposition
Found in the upper course but also at the mouth (isostatic rebound)
-Resistant bands of rock occurring along the course of the river
-Edge of a natural plateau
-Isostatic rebound ­ rejuvenation of the area gives the river more power if the
sea level falls or…read more

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At times of higher flow water swings around one side of a riffle (centripedal
force) undercutting the outer bank on the surface before depositing this
sediment on the inner bank downstream.
In this way an outer concave river cliff is formed and a beach or point bar with a
gentle slip-off slope on the inner bend.
Helicoidal flow results in a surface flow of water to the outer bend and a
corresponding subsurface return flow to the inner bend.…read more

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The valley becomes more asymmetrical, with steep cliffs on the outer
bends and gentler slip-off slopes on the inner bends.
With rapid incision, where downcutting (or vertical erosion) dominates
the valley is more symmetrical, with steep sides and a gorge-like
appearance. These are described as entrenched meanders.…read more

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Causes of Bangladesh Floods 2007
Snowmelt ­ Brahmaputra annual discharge is 19,300 cubic metres per second.
With snowmelt in springtide it increases to 100,000 cubic meters a second. The
Gangstri glacier in the Indian Himalayas feeds the Ganges and is retreated at
25% each year leading to increased snowmelt.
Monsoon Season ­ Monsoon season is usually June to October and up to 500mm
can fall in a day in some areas.…read more

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Effects of Bangladesh 2007 Floods
Social ­
Deaths in excess of 2000.
959 died as a result of diarrhoea, landslides, snakebites and respiratory
9 million homeless.
Damage to infrastructure including 3,000 km of earthen roads and 400km
of paved roads destroyed.
10-25 million people migrated into cities such as Dhaka and Chittagong.
The majority of these were the country's poor who lived on the coast
where land was lost through erosion.
Shrimp farms were washed away destroying the industry.…read more

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Bangladesh Responses
The World Food programme sent energy biscuits for 400,000 people.
The CPP (Cyclone Preparedness Programme) was set up in 1970. It is a
warning system, which uses Asia's largest radio network linking with 143
radio stations. Radio warnings are relayed by 33,000 village-based
volunteers using megaphones and hand operated sirens.
Government of Bangladesh implemented a 2 year promramme called the
Vulnerable Group Feeding Programme.…read more

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Causes of Carlisle, Cumbria January 2005 Flood.
Carlisle Causes
Town developed on the River Eden floodplain.
Low pressure storm event caused heavy rainfall ­ two months rainfall
released in 24 hours.
Large, wide shallow floodplain.
Confluence of 3 rivers ­ Petteril, Eden and Caldew.
Ground already at it's saturation point ­ Previous heavy rainfall in
December meant new rain would just flow over the land. Water was
not able to infiltrate and lead to excessive surface run off.
Mountainous region. Steep gradient.…read more

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Flood Management ­ Ottawa Canada
Steep topography ­ funnel shaped basin.
Discharge increases due to snowmelt.
Peak is in Mid April ­ unregulated flows from southern tributaries cause
water to buildup as there is still ice in the river. (Snowmelt causes the rise in
Peak in Early May ­ High flows from tributaries of Snow Melt in North
together with delayed flows from headwater areas.…read more

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Flood Management ­ Three Gorges Dam ­ China
2km long, 60 storeys tall.
4,000 workers.
17 years.
Produce over 20,000 MW of power. Twice all of UKs nuclear produces.
Central China
Yangtze River
Holds back 22 billion cubic metres of water.
One major flood every 10 years on this river.
Had to divert the river to begin construction.
Move over 1 million people before the area is flooded for the reservoir.
28 million cubic meters of concrete.…read more


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