Hard Engineering Flood Management Schemes

Hard Engineering Flood Management Schemes

1. Dams

   • Huge walls built across rivers. A reservoir (artificial lake) is formed from this. Floodwater is caught by the damn which prevents flooding downstream.
     • Benefits- Turbines are often built into the dams which can generate electricity. They are also used for recreational use. Furthermore, water release can be monitored which allows the irrigation of land below the dam throughout the year.
     • Drawbacks- Land is flooded when a reservoir is first created, destroying farmland, habitats, and forcing humans to move elsewhere. Dams also trap sediment which causes the dam to fail. Because there is less protective sediment being deposited, erosion is increased downstream.

2. Channel straightening

   • Where meanders are removed by building artificial cut-throughs, which make the water flow faster. It reduces flooding because water drains downstream faster and doesn't build up to the point where the river channel can no longer hold it.
     • Benefits- It takes less time to navigate the river as it is shorter.
     • Drawbacks- Flooding may happen downstream instead as flood water is carried there faster. Also, more erosion occurs downstream because the river flows faster. Furthermore, wildlife may be disturbed because their habitat could be destroyed.

3. Levees

   • Embankments built along rivers. The river can hold more water without overflowing and so flooding is less common.
     • Benefits- They allow the flood plain to be built upon.
     • Drawbacks- They are expensive and there is a risk of severe flooding if the levees are breached.

4. Diversion spillways

   • They have channels that take water elsewhere if the water level in the river is too high. Water is normally divert around an important area or to another river.
     • Strengths- The spillways often have gates that can be opened. so the release of water is controlled.
     • Drawbacks- An increase in discharge when he diverted water joins another river could cause flooding there. Also, if spillways are overwhelmed, water will flood areas not used to flooding.