1. Yr 11 Rivers Revision 1 st May 2009

3. Command words Write down what you can see Describe… Give reasons for (how?/why?) Explain… Add labels with details Annotate Write down similarities and differences Compare… Make a list (e.g. bullet points) List… Write down State…

5. The Water Cycle

14. Meander bend on the River Conwy A B A cross section through a meander River Cliff FEATURE Slip off slope Erosion PROCESS Deposition Deep DEPTH Shallow Fast SPEED OF FLOW Slow CONCAVE CONVEX

15. A cross section through a meander

18. So … putting it all together

20. Storm Hydrographs

21. Rising limb Falling limb Peak discharge Peak rainfall storm flow normal (base) flow Hydrographs I = Lagtime

22. What factors increase The risk of flooding? * Impermeable rock * Hard dry soil * Very wet soil *steep slopes * Cutting down trees Building in the drainage basin * Many tributaries

23. Flood protection *Dams hold back flood waters *reservoirs store floodwater *straighten channels Increases speed of flow *Dredging Makes channel deeper so can hold more water *levees and embankments Prevents river from overflowing *land use zoning Restricts development to uses unaffected by flooding *afforestation Increases interception etc, reduces run off

24. Management of water quality and amenities River pollution *nitrates from fertilisers causes eutrophication Water taken from river for cooling in power stations is returned warmer and de-oxygenates water Poisonous / smelling waste from industrial sites Domestic sewage containing dissolved chemicals such as phosphorous from washing powder

25. Rainfall map of t Rainfall map of the United Kingdom Fig 1. - Annual precipitation over Great Britain he United Kingdom Fig 1. - Annual precipitation over Great Britain Heaviest rainfall Areas with most cloud cover Lowest summer temperatures – less loss of water due to evaporation or transpiration Areas with low population density WATER SURPLUS WATER DEFICIT Demand > Supply Rainfall is lower Evaporation and transpiration is high 1/3 UK population lives in SE IN THE WEST IN THE EAST

32. What causes flooding? Impermeable rock deforestation Arable farming Building on floodplains Heavy rainfall Lots of tributaries Marshy areas Very wet soil Hard dry soil steep slopes

33. Flood protection *Dams hold back flood waters *reservoirs store floodwater *straighten channels Increases speed of flow *Dredging Makes channel deeper so can hold more water *levees and embankments Prevents river from overflowing *land use zoning Restricts development to uses unaffected by flooding *afforestation Increases interception etc, reduces run off

36. Wider channel Concrete walls

37. Dam

38. Channel Diversion

39. Homes On Stilts

40. Re-planting Trees

41. Channel Straightening

44. What do you know about drainage basins?