Hard Engineering

Hard Engineering

1. Dams

   • A barrier to obstruct the flow of water
     • +Highly effective
     • + Supply HEP
     • -Silt collects behind dams
     • +Create jobs
     • - Could force people out of homes
     • - Unnatural
     • -Expensive
     • -Flood areas upstream
   • CASE STUDY Three gorges dam

2. Removal of settlements

   • -Expensive/Complicated
   • + 100% flood risk reduction

3. Flood interception Schemes

   • building a bypass channel,using a new channel to store excess water, using embanments
     • -Expensive
     • +reduces flood risk in towns/cities

4. Flood storage resevoirs

   • store excess water in upper reaches of catchment
     • +Natural looking
     • + Can provide water elsewhere
     • -Requires a lot of land
     • -Expensive due to buying land
       • Unless built on cheap high land (little of this in the U.k)

5. Relief channels

   • redirect water around a settlement to re-enter the main channel later
     • +can be used to supply water as well
     • +Natural looking
     • -Expensive so can only be used where it is impossible to alter existing channel

6. Channel improvements

   • Smoother(with concrete), dredging, channel straightening
     • +Move water out of area quicker
     • +Increases channel capacity
     • +Accomodates larger discharge
     • -can increase risk of flooding downstream
     • -requires maintenence
     • -Short term benefits
     • -More erosion downstream
     • -Enlarged channels often arent used and fill with weeds

7. Flood walls, levees and embankments

   • Walls and levees add height to channel
     • +Embankments(if set back from channel) can provide storage for excess flood waters while inhabited areas remain unaffected
     • -Expensive
     • - Eye sore
     • -Could speed up water downstream and flood somewhere else