Case study of a river catchment at a local scale

A local river catchment case study

AQA requires you to study a river catchment at a local scale and use real field data to analyse how precipitation affects stores and transfers within the drainage basin. You must then assess the implications for sustainable water supply and/or flooding.

This page explains exactly what to include and where you can find the data you need, even if your chosen river is different from someone else’s.

1. Start by introducing your catchment

Begin with a brief description of your chosen river. Include:

• The name of the river and its location
• Where it begins (source) and where it ends (mouth)
• The size of the catchment
• Main land uses (farmland, woodland, moorland, urban areas)
• Physical characteristics such as geology, soils and slopes

These factors help explain how the catchment stores and moves water.

Where you can get this information:

• OS Maps
• River Trust or local council webpages
• Digimap for Schools
• Environment Agency Catchment Explorer

2. Describe the physical characteristics

You need to explain how natural features influence the movement of water.

Write about:

Climate and precipitation

• What is the typical annual rainfall?
• Does most rain fall in winter or summer?
• Are there any recent storm events you can use as examples?

Geology and soils

• Are the rocks permeable or impermeable?
• Is infiltration likely to be fast or slow?
• Are there peat soils, clay soils or thin upland soils?

Vegetation

• Does woodland intercept rainfall?
• Does farmland increase runoff?
• Are there wetlands or floodplains that store water?

These characteristics allow you to explain why the catchment responds the way it does during heavy rainfall.

3. Collect or use real data

Even if you cannot collect everything yourself, you must use real field or secondary data.

A) Rainfall data

You can record rainfall using a rain gauge or use online records.

Useful sources:

• Met Office WOW (Weather Observations Website)
• Local weather stations
• BBC Weather past weather data

B) River discharge or river level

Ideally, use a site with a gauging station so you can see how the river responds to storms.

Useful sources:

• Environment Agency river level and flood data
• National River Flow Archive (NRFA)

Look for:

• Rising limb (how quickly a river responds after rain)
• Peak discharge
• Recession limb (how long it takes to return to normal)

C) Soil or groundwater data

If your school has equipment:

• Dipwells to measure the water table
• Soil moisture probes
• Infiltration tests

If not, you can still discuss soil moisture using:

• OR/ local flood reports
• Catchment management reports
• Photos taken after rainfall to show saturation or runoff

4. Analyse how precipitation affects stores and transfers

This is the most important part of your case study.

You must explain what happens to rainfall once it enters your catchment.

Consider: