Hard & soft engineering to control RIVERS UK

Hard Eng - involve MAJOR construction techniques- visibaly intrusive

Soft Eng work with NATURAL process do not involve major construction

  1. fLOOD rELIEF CHANNELS - CHANNEL COURSE OF RIVER ALTERED DIVERTING FLOODWATERS FROM SETTLEMENTS

ADVANTS- no disruption is caused to local residents - residents close by river are safer from floodas water is diverted-can be used as water sports very effect & lasts

Disadvants - extremely expensive - requires large amnt land - might be hard to purchase ie farmland

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hard engineering rivers

Embankments - raised banks along the sides of a river

ADVANTS -can be used pedestrian paths beside river- provide habitats plants & animals - if cncrete stop bank errosion

DISASVANTS - OFTEN NOT BUILT HIGH ENOUDGH - CAN BE UGLY SPOIL VIEW 

CHANNELISATION- A RIVER CHANNELmay be deepened- allowing it to carry more water - or straighned to increase alters travel speed

ADVANTS- EFFECTIVE has it protects immediate area as water moving away faster - long lasting

 DISADVANTS- GREATER RISK OF FLOOD DOWN STREAM - UNATURAL -INTRUSIVE

DAMS CONTROL WATER FLOW - ADVANT STORED WATER CAN GENERATE HYDROELECTRIC POWER

DISADVANTS - SEDIMENT TRAPPED BEHIND WALL - LEADS TO ERROSION DOWNSTREAM . settlements may be lost when river valley flooded to form reserviuor

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Soft Engineering Rivers

Flood plain zoning - local auth &government intro policies to control urban devel close /on flood plains ADVANTS -Sustainable  reduces flood & buil demage . No builing means less surface run off Disadvants - REsistance to resticting developments when there is a shortage of housing  - Planning controls relaxed in LIC s

WASHLANDS=River alloed to flood naturally in wasteland areas to [prevent floods elsewhere .ADVANTS - Natural wetlands for birds & plants - deposited silt may enrich soil - turning it into argricultural land .- large area of land are taken cant be built on - prod land may become marshland

WARNING SYSTEMS - NETWORK OF SIRENS T WARN PEOPLE OF POSS FLOOD -advants- cheap electrical commun very effective way t inform people Disdavants Sirens - vandalised  not enough time 4 residents to prepare

AFFORESTATION - Trees planted to intercept rainfall in catchment area of river-- slows down flow of water to river . ADVANTS - CHEAP SOIL ERROSION IS AVOIDED DISADVANTS SOIL CAN BE ACIDIC -Increase fire risks due to Leisure activities in forest

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EXAMPLE - River NENE -NORTHAMPTON

2002 - level of land at WEEDON was raised by 10 m by building an embankment across the river - water stored behind the embankment in flood times .

2003- flood warning system improved Residents in FAR COTTON  cotton area wud be given 2 hrs notice of flood occurring .

2007- a washland was createdin the UPTON AREA - WHERE 1.2 MILL cubic metres of water cud be stored during x of major flood. major roads A45 ARE ON EMBANKMENTS 6 M HIGH  . Railway station has been protected by building 4 m flood walls at Foot Meadow

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tectonic landscapes

plate tectonics - theory of explanation for location of earth quakes & volcanoes . earths crust dividec into plates . the plates move a few cm s evry year as they float on the mantle . movement is caused by convection currents in the mantle. the movements cause the plates t collide or move apart  .PRESSURE created at the boundaries causes earth quakes & volcanoes

CONVECTION CURRENT -a movement of heated material up through the mantle from earths core to crust .

HOTSPOTS=another place volcanoes occur - fixed points in mantle generating heat - intense heat build pressure - & MAGNA ERRUPTS - MAGNA RISING ABOVE OCEAN SURFACE IS A VOLCANO eXAMPLE galaogos Island  & Hawaii

HOTSPOT - HAWAII ***

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3 TYPES OF convergent plate boundary

  • 1) where continental plate & an oceanic plate meet
  • oceanic plate goes beneath the continentl plate ( its denser )
  • the subduction causes deep trnch
  • earth quake appear here
  • occeani plate melts t form magna
  • magna forces up wards to form volcano
  • land buckles to form mountains 
  • 2 )Whe 2 occeanic plates meet  
  • Earthquake occurs
  • occeanic plate melts t foirm magna
  • magna forces its way up through cocean to form vocanoe  
  • 3 )where 2 continental plates meet
  • crust rises to form fold mountains
  • earthquakes occur here
  • no volcanoes as crust not melted & subduedl
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DIVERGENT & CONSERVATION PLATES

Divergent plate boundry - usually form under the occean - volcanoes created by occean ridges .

  • as plate moves apart a gap is left
  • magna forms new crust in gap between plates
  • if magna reaches the oceab surface a volcano will emerge

COnservation plate boundry- when plates move alongside each other in the same direction at different speeds or in different directiions

  • Earthquakes occur as they rub together as they become stuck at a pressure point 
  • eventually the crust will snasp & pates will move

***diagrams labeelled ***

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measuring EARTHQUAKE MAGNITIUDE

  • 2 diff between MERCALLI & RICHTER SCALES

Mercalli is subjective -wheras richerter scale is objective .

Richter scale is measure by a seismograph whereas the MERCALI SCALE IS MEASURED BY EYE.

Mercalli

measured ment of intensity of earhquake completed from eye witness accounts

measure on scale 1-12

person measuring it has t be at earthquake site.

Richter Scale

measurement of magnitude of earthquake byseisomograph

measurement scale is 1-9 (each no split into 10 pts) 

measurement can be at different location . 

Epicentre on earthd surface - where worst effects of earth quake felt - inhabited where worst destruction infrastructure felt

FOCUS - point below earth surface - it is the point pressurebuil-up is released-shockwaves move out of this point

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reasons why people live in areas of volcano

Economic - - soils very fertile - cheap geothermal energy is produced in these areas EGS Coffee grown on slopes of volcanoes in Colombia - Iceland Reyjavik cheap electricity

Social - People think little risk of happening or Government will help -all family & friends their 4 yrs - poverty cant afford tio move LIC  eg Etna Italy familys on slopes

usa MT ST H elens erupted people refuse t move Environmental - scenic area & mant tourist visit - Mt Etna in SItourist shops - jobs trade peoples

Earthquake living  

Economic -scenic Areas - tourist industry jobs & mining industry in areas cOPPER MINED IN ChilE 2007 x2 people died people will take risk 4 jobs - Iceland tourist shown areas Social - wont happen to me or gov precauctions taken - Japan earthquake buildings safer Enviromental- Fantastic scenic venues foe wealthy -wont move - Malibu coastal resort usa

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VOLCANIC ERRUPTION -Montserrat 1997

  • CAUSES - Volcanic Island on a Destructive Plate boundary
  • THe plates that meet are North American plate & Caribbean
  • 1997 Chances Peak Volcano errupted
  • Hugh ash cloud covering southern part pf island
  • Polyroclasticflows of hot rock & ash thrown from volcano

Effects on people

19 KILLED FROM POLYCLASTIC FLOWS

  • Villags destroyed farm & trant
  • 150houses destroyed
  • transport routes destroyed- Bramble air port - closed aid disrupted- roads blocked rocks ash
  • people left never returned lost everything PSYCHOLOGICAL

Effects on Environment - 4 sqkm covered in ash/rocks

  • Flows Pyroclastic caused river BELHAM TO FLOOD  
  • pyroclastic flows removed vegetation in south of island incl ridges surrounding Farrell s yard
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exam practice - volcanoes

Using Egs - Give reasons why people continue to live in areas of volcanic activity .

Environmental reasons - beautiful scenery - attracts wealthy people want to live there Mtn Etna

  •   Economic reasons - tourist come / money & jobs for local people mtn Etnain SICILY. Coffee is grown on slopes in Colombia . electric power Reykjakic iceland
  • Social Reasons - people think there is liitle risk & want t live near family & friends . Poverty in LIC countries cant afford to move .  
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Prediction of Earthquakes & volcanoes

EARTHQUAKES

  • Prediction - Earthquakes - SEisometer - measure movement - can predict when earthquake is likely tro happen
  • building design /defence -- earthquake proofie automatic shutters-come down over windows-eg san francisco airport has colomns on ball bearings - it moves with the quake
  • education & planning Japan schools 76 business practice quake drills ie ducking under tables - . USA governments have info packs on how to pre-opare foe quakes
  • VOLCANOES
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