Managing floods

Hard engineering

builds structures to control the river.

Method	Benefits	Costs
store water upstream and release it slowly	Control floods; can supply water and power	Very expensive; flood valleys; trap sediment
Straightening: cutting through meanders	Water flows away faster	Can move the flood risk downstream
raising the banks	Hold more water in the channel	Expensive; can fail, flooding the land behind
a second channel that takes extra water	Carry floodwater around a town	Expensive to build; may flood if overwhelmed

Key terms

Soft engineering

works with the river's natural processes.

Method	Benefits	Costs
Flood warnings and preparation: alerts and plans, sandbags, flood gates for homes	Cheap; gives people time to protect themselves and move belongings	Don't stop the flood; people must act on them
limiting building on the flood plain	Fewer homes at risk; the land can flood safely	Limits where towns can grow
Planting trees (afforestation)	Trees catch rain and slow runoff; create habitats	Takes years to work; land can't be farmed
River restoration: letting a river meander and flood naturally	Slows water; restores wetlands	Nearby farmland floods

Key terms

Banbury: why a scheme was needed

Banbury is a market town in Oxfordshire, on the River Cherwell. The shape of its valley makes it likely to flood after heavy rain.

At Easter 1998, heavy rain caused a flood that closed the railway station and many roads. About 125 homes and 35 businesses were flooded, causing more than £12.5 million of damage.
In the summer of 2007, it flooded again.

The Environment Agency drew up a scheme in 2001, but changes to its funding and public inquiries delayed it. Building began in 2011.

Banbury: the strategy

The Banbury Flood Alleviation Scheme, completed in 2012, has five parts:

a 2,850 m long earth across the Cherwell's flood plain, upstream of the town, holds back floodwater and lets it out slowly. Shaped openings control the flow, so it needs no gates, power or operator.
A raised road: 860 m of the A361 was raised, so it stays open in a flood.
Local defences: embankments, flood walls and a 210 m sheet pile wall protect industrial estates and the football club.
A pumping station at Moorfield Brook pumps water into the river below the town.
ponds, trees and hedgerows.

Key terms

Banbury: the issues

Social: about 441 homes now have a lower risk of flooding, and people worry less. New footpaths and a country park were created.

Economic: the scheme cost about £18.5 million, but it protects 73 businesses, the railway and the town's roads, which flooding had cost more than £12.5 million in 1998 alone. Lower risk can make home insurance easier to get.

Environmental: 12 hectares of new habitat were created, with ponds, trees, hedgerows and stretches of river moved to meander. Farmland in the storage area floods from time to time. Digging uncovered prehistoric flint tools and medieval field patterns, which archaeologists recorded.

Judgement: the scheme cost less than the damage two floods like 1998's would cause, and added habitat, but some farmland now floods on purpose.

Exam practice

Plan your own answer first, then open the model answers to see what each level looks like.

9 marks · about 9 minutes

Using an example, evaluate the social, economic and environmental issues of a flood management scheme.

Evaluate means: Judge strengths and weaknesses or successes and failures, then reach a conclusion.

Link it

Use the facts from:

Banbury Flood Alleviation Scheme (Banbury, Oxfordshire, on the River Cherwell, 2011 to 2012)

Level 1 (Basic)· 3/9 marks (band 1–3)

Banbury has a flood scheme. It protects houses but cost a lot of money.

Why this level: A named scheme with simple points, but the three types of issue aren't covered and there's no judgement. To reach Level 2: explain the social, economic and environmental issues with facts.

Level 2 (Clear)· 5/9 marks (band 4–6)

Banbury flooded in 1998, causing more than £12.5 million of damage. The scheme, completed in 2012, built a 2,850 m embankment to store floodwater upstream. Socially, about 441 homes now have a lower flood risk. Economically, it cost about £18.5 million but protects 73 businesses. Environmentally, it created 12 hectares of habitat.

Why this level: Clear, accurate social, economic and environmental points. But they aren't evaluated, and there's no judgement. To reach Level 3: weigh the benefits against the drawbacks, then judge whether the scheme was worth it.

Level 3 (Detailed)· 8/9 marks (band 7–9)

Banbury, on the River Cherwell, flooded at Easter 1998, damaging about 125 homes and 35 businesses and causing more than £12.5 million of damage, and flooded again in 2007. The scheme, completed in 2012, built a 2,850 m earth embankment to hold floodwater in a storage area upstream, and raised 860 m of the A361. Socially, about 441 homes now have a lower flood risk, reducing worry and disruption, and new footpaths were created; however, building was delayed for years by funding changes and public inquiries. Economically, it cost about £18.5 million, but it protects 73 businesses, the railway and a main road, and one flood like 1998's would cost most of that. Environmentally, it created 12 hectares of habitat, with ponds, trees and meanders, though some farmland now floods on purpose. Overall, the benefits clearly outweigh the costs, because it protects many homes and businesses while improving the environment.

Why this level: Detailed, accurate evidence for each type of issue, with drawbacks weighed against benefits and a supported judgement. This is Level 3.

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