There is discussion about the costs and benefits of hard and soft engineering and debate about which is the better option.

There are two main ways in which you can manage rivers: hard and soft engineering. Hard engineering focuses on humans trying to control the environment and tends to be more expensive. Soft engineering aims to work with the environment and is more ecologically sensitive.

Hard engineering

Raised river banks

Higher banks means the river can hold more water

One off costs

Relatively cheap

Can be used in local, small-scale projects

Looks unnatural

Increases risk of flooding elsewhere

Straightened river channel lined with concrete

Water will flow quicker through a straighter channel.

One off costs

Stops local flooding

Can be used in local, small-scale projects


Increases risk of flooding elsewhere

Deepened river channel

River is deeper so can hold more water

Channel can hold more water

Reduces flooding

Dredging is an annual job

Dams and reservoirs

Trap and store water and release it in an controlled way.

Controls river

Resevoirs are multi-purpose and provide electricity

Very expensive

Reservoirs flood local ecosystems

Dams trap fertile silt

Flood walls

Raised walls built around settlement, industry or transportation

Effective if the flood is not too extreme


Looks unnatural

Flood storage areas

Water is pumped from rivers and stored in temporary lakes.


Relatively natural

Large areas of land needed

Expensive to set up

Tidal barrier

Prevents flooding at high tide.

Protects large areas ‘at once’

Very expensive

Only suitable in estuaries

Soft engineering


Plant trees to increase interception and absorb water

Environmentally aesthetic

Relatively cheap and one-off cost

Large areas of land needed for tree planting

Floodplain zoning

Closeness to river governs landuse.

Land use close to river used for animal grazing

Land furthest from the river used for ‘expensive’ land use, such as hospitals

Does not prevent flooding

Flood prediction and warning

The Environment Agency monitors rainfall and river levels and issues warnings to the public.

Public are aware of the risks and can take appropriate action

Involves many people

Continuous nature means that it is expensive

Does not prevent flooding


Parts of the floodplain are allowed to flood.

Prevents valuable land flooding

Land can’t be ‘built’, requires low value land to be available for flooding