Flood causes and consequences
Explain how relief, soil, land use, climate and coastal events contribute to flooding and how floods affect people, infrastructure and ecosystems.
This original StudyForA sequence supports Cambridge IGCSE Environmental Management 0680 Topics 1–4 for exams in 2027, 2028 and 2029. Named local examples are chosen by the learner and centre; verify current conditions and local context with reliable sources. It is not a Cambridge paper, official grade or complete course.
Before you begin
- Use the 2027–2029 syllabus and check your exam year and centre's entry arrangements. Topics 1–4 are taught on this page; Topics 5–7 are still being built.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
Which is a coastal flooding cause listed in the syllabus?
What you will learn
- Explain how relief, soil, land use, climate and coastal events contribute to flooding and how floods affect people, infrastructure and ecosystems.
- Use evidence from an unfamiliar case to explain a cause-and-effect link and justify a suitable response.
Explain causes of flooding
Land relief affects how water moves and collects. Saturated or compacted soil can reduce infiltration; soil erosion can increase runoff or sediment movement.
Deforestation, agricultural practices and urbanisation can change interception, infiltration and surface runoff. Climate change can contribute through sea-level rise and more extreme weather. Storm surges and tsunamis can also cause coastal flooding.
Trace social and environmental impacts
Flooding can damage buildings and infrastructure and cause loss of crops, livestock and habitats. People and livestock may be evacuated; floods may trigger landslides and contaminate drinking-water supplies.
Water-related disease, financial losses and harm to human health can follow. The impacts depend on depth, speed, duration, warning, exposure and the quality of water and infrastructure.
Use a pathway rather than a list
Explain how a cause leads to water accumulation or movement, then connect it to an exposed person, asset or habitat. Urban surfaces may increase runoff, while low relief can allow water to collect.
Do not assume all floods have the same cause. A river flood, coastal storm surge and tsunami may require different evidence and responses.
Sources for this lesson
Pause and explain
How can urbanisation contribute to flooding?
Worked example
After intense rainfall, a compacted urban catchment floods and contaminates a water supply. Explain two contributing factors and two impacts.
Show the worked solution
- Compacted soil and urbanisation can reduce infiltration or increase surface runoff; intense weather can add more water than drainage can manage.
- Low-lying relief may allow water to collect, depending on the site.
- Flooding can damage infrastructure and contaminate drinking water, creating health risks and financial losses.
Answer Compaction, urban surfaces and intense weather can contribute to runoff and flooding. Damage and water contamination are possible impacts, but site evidence is needed to establish their relative importance.
Try a topic test
Choose Easy, Normal or Difficult. Save your answers and open worked review after finishing.
Test this topic →From guided practice to a new situation
Write your answer and reasoning first. Use a hint only if you are stuck. The model solution is for self-checking; your written work is not automatically marked.
A steep catchment has saturated soil after prolonged rain. Explain how relief and soil saturation can contribute to a flood and name one likely impact.
Give me a hint
Trace runoff and accumulation, then connect water to an exposed feature.
Compare my reasoning
- Saturated soil has limited remaining capacity to absorb additional water.
- Steep relief can move runoff quickly toward lower areas where water may collect.
- The flood may damage infrastructure, affect crops or habitats, contaminate water or harm health depending on exposure.
Saturated soil and steep relief can increase runoff and downstream accumulation. The impact depends on what lies in the flood path.
Look for these in your work
- Soil condition explained
- Relief linked to movement
- Impact tied to exposure
A coastal settlement experiences a storm surge while an inland town experiences river overflow. Explain why the causes and useful evidence differ.
Give me a hint
One is a coastal sea-level event; the other involves a river catchment and rainfall or flow.
Compare my reasoning
- A storm surge pushes coastal water inland and is one listed flooding cause.
- River overflow can depend on rainfall, catchment relief, soil saturation, land use and river levels.
- Use coastal water-level and storm data for the settlement, and rainfall, discharge, relief and soil or land-use evidence for the inland town.
The flooding mechanisms differ, so compare evidence suited to each setting rather than applying one explanation to both.
Look for these in your work
- Coastal and river mechanisms distinguished
- Causes tied to setting
- Evidence matched to process
A flood damages a road, crops and a water source. Explain one chain of consequences for people and identify records that would help estimate recovery needs.
Give me a hint
Connect damaged assets to access, food, health or income.
Compare my reasoning
- A damaged road may interrupt access to schools, work, supplies or emergency services.
- Crop loss can reduce food and farm income; contaminated water can increase health risks.
- Use infrastructure damage surveys, crop and income records, water tests, disease information and household needs to estimate recovery support.
Several impacts can combine: access, income and health may all be affected. Recovery needs should be estimated from local damage and health evidence.
Look for these in your work
- Consequence chains explained
- Food or health included
- Recovery data are relevant
Common mistakes
- Attributing every flood to climate change alone
- Ignoring land relief and soil conditions
- Equating a storm surge with river overflow
- Listing impacts without explaining exposure
What can you explain now?
Which condition can reduce soil infiltration?
Compare with the explanation
Compacted soil
The correct answer is “Compacted soil”. The alternatives “A wildlife corridor” and “A seed bank” do not match the syllabus concept. Explain how relief, soil, land use, climate and coastal events contribute to flooding and how floods affect people, infrastructure and ecosystems.
After trying it yourself, choose your next review. This is your self-assessment.
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Make it stick
Explain flooding causes through physical and human factors, then trace impacts using local exposure evidence.
If you needed the solution, close it and solve the problem again from a blank page. A correct answer is stronger when you can explain the reason for each step.