Edexcel IGCSE Geography Chapter 1 - Pearson Schools

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estoring a river to its natural state or preserving marshes and wetlands on floodplains to act as valuable temporary stores of floodwater (like sponges). Otheractions include stricter planning controls to ensure that there is little building onthe flood plain. People in flood-risk areas should be encouraged to take out floodinsurance. Putting in place better flood warning systems would help; so too wouldpublicising what to do in an emergency.<strong>Chapter</strong> 1: River environmentsHow might improved weather forecastinghelp the prediction of floods?Prediction − Prediction of river floods (their extent and depth) is important to floodcontrol. Knowing how high, or wide a river can flood, helps people to decide, forexample, how high river embankments need to be built. It also helps to avoid buildinghouses, factories and services in areas of where there is a high risk of flooding.The problem with prediction is that floods vary. Small floods are likely to occurfairly regularly – say, once every five years. Large floods may be expected lessfrequently – possibly once every 50 years. Perhaps once every 1000 years therewill be truly exceptional flood of a huge scale. The question for river managers is todecide for which level of flood they should provide protection. This is known asrisk assessment. Protecting against the regular five-year flood is going to berelatively cheap and easy. However, is it worth investing huge sums of money toprovide protection against the hugely damaging ‘once-in-a-1000-years flood’? Inmany cases, river managers will take a middle course and aim to be able to dealwith the medium threats of the 50 to 100-year floods. Clearly, where the risk isunder assessed, protection is likely to prove inadequate.Case study: Flood management in BangladeshNC H I N ADelhiNGangesHIE PM AKathmanduA LL AY ATsangpoSPadmaTIBETLhasaBHUTANJamunaASSAMDhakaBramaputraMeghnaBANGLADESHI N D I ABay of BengalMYANMAR0 300 kmFigure 1.38: Catchment area of the rivers of BangladeshEighty percent of Bangladesh and 90% of its over 100 million people live lessthan one metre above sea-level on the floodplains and delta of three verylarge rivers − the Ganges, Brahmaputra and Meghna (Figure 1.38). Bangladeshis the world’s most flood-affected country. Flood management in this LIC isliterally a matter of life or death. Major causes of the annual flooding include30
the monsoon climate with its heavy summer rainfall and tropical storms withthe tidal surges that they cause. Melting Himalayan snow in summer anddeforestation in Nepal are two other flood risk factors.The Bangladeshi Flood Action Plan (FAP) funded by the World Bank began in1990 and involves:●●●●building up embankments to protect the main cities, towns, roadsand farmland (Figure 1.39)dredging channels that have been silted up so that they hold more floodwaterstraightening river channels to prevent erosion of banks or meandersconstructing dams upstream to control flood waters before they reachthe delta●●●●allowing controlled release of floodwater from river channels via spillwaysthat have been constructed to allow the controlled release of flooding watersbuilding huge reservoirs to hold some of the floodwaterimproving flood forecasting and public warning transmission systemsbuilding emergency shelters on areas of slightly higher ground.The FAP involves a mix of hard- and soft-engineering action, but more of theformer. It is a long-term project and will continue to require more fundsthan the Bangladeshi government can afford. Achieving effective floodmanagement there is being made more challenging by two developments:●●the threat of global warming – itonly needs a slight rise in sea levelin the Bay of Bengal and much ofBangladesh will be flooded by thesea. Bangladesh badly needs toimprove its coastal defences. On topof that, any rise in sea levelwill make it even more difficultfor Bangladesh to get rid ofits floodwaterthe three rivers of the Bangladesh’sdelta area all flow for considerabledistances through neighbouringIndia (Figure 1.38). Relationsbetween Bangladesh and India arenot always good. India could helpBangladesh by improving control ofthe floodwaters of these riversbefore they reach Bangladesh.Equally India could pass thefloodwaters on at an even fasterrate and increase even more theflood risks in Bangladesh.Figure 1.39: Mud embankments being builtby handIn your own words, suggest a definitionfor the term ‘ flood management’.<strong>Chapter</strong> 1: River environments31
Page 1 and 2: Section A:The natural environment a
Page 3 and 4: ●●●●overland flow - most of
Page 5 and 6: shows the channel networks of two d
Page 7 and 8: There are a number of factors affec
Page 9 and 10: ErosionThere are several different
Page 11 and 12: KeyDifference inheight betweenX and
Page 13 and 14: As lateral erosion continues, the b
Page 15 and 16: The height of the drainage basin an
Page 17 and 18: ●●●The rising standard of liv
Page 19 and 20: uses less water (now 14%) (Figure 1
Page 21 and 22: 1.7 Water qualityIn Part 1.6, we lo
Page 23 and 24: Agriculture●●●Liquid from far
Page 25 and 26: There is a fourth and relatively ne
Page 27 and 28: FACTORPhysicalWeatherRockSoilRelief
Page 29: In the longer term, there is the co

Edexcel IGCSE Geography Chapter 1 - Pearson Schools

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