River Flood Risk Lab
The same river that carves valleys can also flood towns. Using the River Exe, weigh up flood risk and the two great choices for managing it: build hard defences, or work with nature.
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From source to sea, and flood risk 🌊
The **River Exe** rises on **Exmoor** and flows south through Devon to the sea at Exmouth, passing the city of **Exeter**. Along its course it shapes the land, but it can also **flood**. This module looks at **flood risk** on a river like the Exe, and at the two big ways of managing it: **hard** and **soft** engineering.
Key terms 🔑
Four ideas run through flood management:
Where does the flood plain form? 🗺️
Along a river long profile, where is the wide, flat flood plain, the area most at risk of flooding, found?
- In the lower course, near the mouth
- In the upper course, near the source
- Only at the exact source
- Rivers do not have flood plains
Match each management method 🔗
- Dam and reservoir
- Artificial levee
- Flood-plain zoning
- Afforestation
- A large barrier that holds water back in a reservoir
- A raised bank along the river to stop it overtopping
- Planning rules that keep houses off the flood plain
- Planting trees in the catchment to slow the runoff
Hard vs soft engineering ⚖️
There are two contrasting ways to manage flood risk.
Spot the soft methods ✅
Select the TWO soft-engineering approaches to flood management.
- Flood-plain zoning, keeping building off the flood plain
- Afforestation, planting trees across the catchment
- Building a large concrete dam
- Building high flood walls along the banks
A named river: the Exe 🏞️
In the exam, use a **named example**. The **River Exe** drains **Exmoor**, whose steep, wet and impermeable moorland sends water quickly downstream. After heavy rain, the Exe has flooded **Exeter**, damaging thousands of homes in the past. Flood defences, such as walls and channel works, were later built to protect the city. Naming the river and the flooding is what earns the marks.
Why choose soft engineering? 🌱
Why might a council choose soft engineering rather than hard engineering to manage flood risk?
- It usually costs less and is more sustainable, working with natural processes
- It completely guarantees that no flooding will ever happen
- It uses more concrete than any other method
- It stops all rivers from flowing at once
Complete the picture 🧱
The chance that a river will overflow and cause damage is called flood _____. Building structures such as dams and flood walls is _____ engineering, while working with nature by planting trees is _____ engineering. The wide, flat area beside a river that floods is the flood _____. On the River Exe, heavy rain on Exmoor can flood the city of _____.
How a flood develops 🪜
An interactive activity.
Tap the soft approaches 🖍️
An interactive activity.
Manage the flood risk 🔀
An interactive activity.
Evaluate the options ✍️
An interactive activity.