How does a river change from source tomouth?GradientChannel depthspeedChannel widthWith a partner answer the above question. Draw small sketches if you wish to helpyou explain.landforms
The long Profile of a RiverCopy thisdown ontoyour A3 sheet• Steep gradient• shallow/narrow channel• large/angular ‘bedload’ • wider/deeper channel• gentle slope• open floodplains• ‘bedload’ is smaller and more rounded• very wide and deep channel• gentle slope• flat and wide open floodplains• most ‘bedload’ is carried in ‘suspension’
Exam question (2010)5 (a) Study Figure 14 which shows a long profile and cross profiles of a typical river.Figure 14Describe how the cross profile changesdownstream (3).
DepositionDeposition is when a river drops any eroded material ithas been transporting•Rivers will always deposit the heaviest bedload first•The smaller the bedload the further it can betransported.WHY DO RIVERS SLOW AND DROP MATERIAL?• The volume of water falls in the river• The amount of eroded material in the water is increased• The water is shallower (inside of a meander/bend)• The river reaches its mouth
river disappears fromview hidden by this spurof landUpper Valley -River Conwy(near MignantMoor)Landforms in the upper course created by erosionV-shaped valleys and interlocking spursRapidsWaterfalls
V shaped valleys and Interlocking spurs• VerticleVertical erosion inthe upper coursecreates a V-shapedvalley. This is a steepsided and narrowvalley.Soil and loose rockare moved downhill by slope-washand soil-creepThe river winds its wayaround interlocking spursof hard rock (notmeanders)Steep valley gradient and noflat valley floor. The channelis narrow and shallow. Largeangular rocks are found as theriver has not has time to grindthem down by attrition andabrasion.Velocity is highat rapids andwater falls butslower elsewhere as theriver has toovercomefrictionAdd notes todiagram
FloodplainsThe rivers floodplain is thewide, flat area of landsurrounding the river. Thefloodplain is shaped asmeanders cut their waythrough by lateral erosionand deposition of material onthe inner bend of a meanderand at times of flood buildsup the valley floor.The floodplain is formed by both erosion and deposition.
During flooding, as a river spillsonto the surrounding land, there isa reduction in the velocity of thewater due to an increase in frictionbetween the water and thefloodplain.This results in a loss of energy which causes deposition of thelarge quantities of suspended sediment that a river carries as itenters its lower course.Floodplains
What does a hydrograph look like?Label yourhydrographwith thefollowingsentences.
What do hydrographs look like?Flashy SubduedWhat do you think the differences are betweenthe hydrographs?
Interpretation of StormHydrographs•Rainfall Intensity•Rising Limb•Recession Limb•Lag time•Peak flow compared to Base flow•Recovery rate, back to Base flowYou need to refer to:Basin lag time0 12 24 36 48 30 72Hours from start of rain storm321Discharge(m3/s)Base flowThrough flowOverlandflowmm432Peak flow
Morpeth floods 2008In early September the RiverWansbeck, which flows through thetown centre, could take no more after awet summer, & a particularly wetAugust was followed by more than thewhole of Septembers rain falling within48 hours. The heavy, persistent raincame from an active area of lowpressure, which spent the weekendover north-east England, moving only alittle.Morpeth, Northumberland 2008
Yorkshire Floods in 2007The summer floods of 2007 affectingsouth & east YorkshireA prolonged period of wet weather,much higher than average rainfall, &concentrated periods of heavy rainfall,all of which precipitated the veryserious local flood events. A year later,many of the affected households hadstill not fully recovered.
Your Case Study for a floodin the rich world:-Boscastle UK 2004
For this case study you willneed to know the following:-(Same case study as Weather!)• Where is Boscastle located?• What caused the flash flood?• What were the social effects?• What were the economic effects?• What were the environmental effects?• What was the response?• How is the flood risk being reduced forthe future?
Your Case Study for a FLOOD inthe poor world:-Bangladesh,2004
For this case study you willneed to know the following:-• Where is Bangladesh located?• What caused the flood?• What were the social effects?• What were the economic effects?• What were the environmental effects?• What was the response?• How is the flood risk being reduced forthe future?
Turn to the front of your exercise book. Write the following:-• In my end of unit test for Japan, I achieved a Level _____.• I think the effort I put ino this topic was Excellent/VeryGood/Satisfactory/Poor.• The thing I enjoyed the most about this topic was……• In order to improve in my new topic (Volcanoes andEarthquakes) I will………
Flood Control:Should hard or soft engineering be used?This comes under the heading of river basinmanagement – planning ahead and controlling change.Hundreds of millions of people throughout the worldlive close to rivers. Management methods are neededto try to reduce the risks from flooding.
Key definitions:Hard engineering:The use of technology to control rivers, ofteninvolving large and expensive projects.Soft engineering:Trying to work within the limits of the natural riversystem. No permanent structures are built.Multi-purpose project:A large scale idea with more than one aim. Many waterprojects aim to control floods and water supply
Decide whether each of these flood control methods isan example of hard or soft engineeringDamsLand use zoning Raise leveesWarningsPreparationPlant treesFlood wallsStraighten river
Positives and negatives of hard engineeringImmediate resultsGreatest protectionin the short andmedium termHuge controlover the riverLarge projects couldhelp to improve watersupply, provide HEP,or leisure activitiesExpensive to buildRequire costlymaintenanceCould makeproblems worsein the futureCould createunforeseenproblemsWhere there is high social,economic and political needtheir use is not optional
Soft EngineeringHow do these methods help to reduce the risk of flooding?Land use zoningWarningsPreparationPlant trees...or do nothing!!
Key WordsWater Surplus – Areas that have more waterthan is needed – often such areas receive a highrainfall total, but have a relatively smallpopulation.Water Deficit – Areas that have locations where therain that falls does not provide enough water on apermanent basis. Shortages may occur under certainconditions. E.g long periods without rain.Water Stress – This occurs when the amount of water available does notmeet that required. This may be due to an inadequate supply at a particulartime or it may relate to water quality.
Study the information about flood control on the River TeesCow Green Reservoir Yarm defences Tidal Moutha) Fill in the table identifying the hard and softengineering strategies that are used.b) Which one dominates – hard or soft? Explain why.
Why has demand for waterincreased in the UK?• The population has increased and is expected to increaseby around 10 million over the next 20 years. This meansmore water used for washing/drinking etc.• A more affluent lifestyle. People are buying more timesaving goods like washing machines and dishwashers thattake up more water.•We demand foodstuffs out of season which contributes toan increase in overall use of water.• Electricity Power Stations use water for cooling.• Demand for electricity in offices, industries and homes,and for transport.
• Taking showers instead of baths• Running water machines and dishwashers onlywhen full.• Using hosepipes less•Install water metres into our homes! Metreswould be used to charge people for the exactvolume of water they use. People with watermetres are likely to be careful with the amount ofwater they use – they’re paying for every drop.•Houses designed with better water efficiency•Rainwater can be collected.
Case Study: a dam and reservoirKielder Water, NorthumberlandPlanned in the late1960s to satisfy anincrease in demandfor water from thethen growingchemical and steelindustries onTeesside.Opened in 1982.
Why this location?Characteristic of the site Benefit of thisA valley with a wide floorand steep sloping sidesHigh annual precipitation(1370mm)Very sparse humanpopulationPoor quality farmland farfrom the marketsRough grazing andconiferous woodlands
Draw a sketchmap to show howrivers are usedfor watertransfers fromKielder Water
The BenefitsNorth East Englandenjoys the most reliablewater supply in EnglandEven in the driestsummers (e.g. 1995)restrictions on water useare unknown in the regionA pipeline has beenconstructed to supplywater for use in YorkOver 250,000 visitors areattracted by outdooractivities each yearKielder Forest, surroundingthe reservoir, is the largestwoodland in EnglandJobs in the water industry,tourism and forestry existwhere there was onlypreviously farmingBiological studies haveshown no adverseeffects on wildlife inconnected river systems