Man-made structures built to control the flow of rivers and reduce flooding.
Dams and reservoirs
Dams are obstructions in water that create reservoirs, preventing water from flowing downstream.
Reservoirs are artificial lakes that form behind a dam
What are the advantages of dams and reservoirs?
Dams store water, it controls the flow of water, prevents flooding downstream, can also be used to produce hydroelectric power
What are the disadvantages of dams and reservoirs?
Dams are very expensive to build. Creating a reservoir can flood existing settlements.
Eroded material is deposited in the reservoir and not along the river's natural course so farmland downstream can become less fertile.
Channel straightening
Removers meanders creating a straighter route
Flood risk is reduced as water leaves the channel faster
Faster moving water means more erosion downstream so more potential floods downstream
Embankments
Raised banks constructed along the river; they effectively make the river deeper so it can hold more water. They are expensive and do not look natural but they do protect the land around them.
Flood relief channels
Building new artificial channels which are used when a river is close to maximum discharge. They take the pressure off the main channels when floods are likely, therefore reducing flood risk.
- Gates are used to control flow HOWEVER the relief channels rejoins water causing more floods
