Soft Engineering River Management

Soft engineering river management schemes work with the natural processes along the river to reduce the risk of flooding.

Flood warnings and preparation

UK flood alert map – click to view current alerts.

Flood warnings and preparation involves developing a system of alerting people to the risk of flooding. In the UK, the Environment Agency is responsible for warning people about flooding through the TV, Radio, Internet, newspapers and apps.

Advantages 

The impact of flooding is reduced as people are better prepared. There is more time for people to move things upstairs, put sandbags and other flood defences in place and evacuate.

Disadvantages 

Warnings do not stop a flood event. Not all people will be aware of flood warnings.

Floodplain zoning

Floodplain zoning involves putting building restrictions on floodplains at risk of flooding.

Advantages 

Buildings are not constructed in areas at risk of flooding. Impermeable surfaces are not constructed on the floodplain, so the risk of flooding is not increased.

Disadvantages 

The growth of urban areas can be limited if building on floodplains is restricted. The risk of flooding is not reduced in areas of floodplains that are at risk of flooding but have been built on in the past.

Planting trees

Afforestation

Planting trees increases interception and lag time (the time between the peak rainfall and peak river discharge). This reduces the risk of flooding.

Advantages 

Discharge in the river is reduced. The trees also reduce the risk of soil erosion, which can reduce the capacity of the river channel to carry water.

Disadvantages 

Restricts what land can be used for, particularly in the upper stages of the river valley.

River restoration

River restoration

River restoration involves returning a river to its natural state. This can involve removing man-made levees or removing river straightening.

Advantages 

Discharge in the river reduces, meaning there is less risk of flooding downstream. Little or no maintenance is required, which makes this a low-cost solution. Biodiversity is maintained along the river.

Disadvantages 

Flood risks can increase if nothing is done along the river.