hard vs soft engineering

• what is hard engineering?

  man-made structures built to control the flow of rivers and reduce flooding
• what is soft engineering?

  schemes set up using knowledge of a river and its processes to reduce the effects of flooding
• what are the 4 methods of hard engineering in rivers?

  dams and reservoirs, channel straightening, embankments and flood relief channels
• what are the benefits of dams and reserviours?

  stores water, prevents floods downstream and can be used to create hydroelectric power
• what are the disadvantages of dams and reservoirs?

  are expensive, creating a reservoir can flood existing settlements and farmland downstream can become less fertile
• what is channel straightening?

  meanders are removed by building straighter - artificial channels
• what are the benefits of of channel straightening?

  flood risk is lower as the water leaves the area more quickly rather than building up
• what are the disadvantages of channel straightening?

  flooding may happen downstream instead, faster flowing water may also cause more erosion downstream
• what are embankments?

  raised walls that are built along river banks
• what are the benefits of embankments?

  the river can hold more water so floods are less frequent
• what are the disadvantages of embankments?

  quite expensive, risk of severe flooding if water rises above the level or if embankments break
• what are flood relief channels?

  channels that are built to divert water if the river level gets too high
• what are the benefits of flood relief channels?

  gates on the channels mean that the release of water can be controlled reducing flood risk
• what are the disadvantages of flood relief channels?

  there will be increased discharge where the relief channel rejoins the river which could cause flooding in that area
• what are the 4 soft engineering strategies in rivers?

  flood warnings and preparation, flood plain zoning, planting trees and river restoration
• what are the benefits of flood warnings and preparation?

  warnings give people time to prepare and evacuate which reduces the impact of flooding
• what are the disadvantages of flood warnings and prepartion?

  modifying buildings can be expensive, doesn't guarantee safety
• what is flood plain zoning?

  Regulating land use in flood-prone areas.
• what are the benefits of flood plain zoning?

  fewer impermeable surfaces(roads) are creating therefore reducing flood risk. The impact of flooding is also reduced as there is no buildings to damage
• what are the disadvantages of flood plain zoning?

  Limited development opportunities, can't help in areas with existing buildings
• what does planting trees do and where are they placed?

  they are planted in the river valley which increases the interception of rainwater
• what are the benefits of planting trees?

  reduces soil erosion, provides habitats and discharge and flood risk decrease
• what are disadvantages of planting trees?

  there is less land is available for farming
• what is river restoration?

  making the river more natural(removing man-made levees)
• what are the benefits of river restoration?

  little maintenance, create better habitats and discharge is reduce so less flooding downstream
• what are the disadvantages of river restoration?

  local flood risk can increase but prevent major flooding