Drainage Basin as an Open System

Active learning helps students visualize the dynamic nature of drainage basins. Working with physical models and simulations makes abstract concepts like inputs, outputs, and flows concrete and memorable.

• Year 12
• Geography
• 3 activities
• 25 min–50 min

Learning Objectives

1. Analyze the drainage basin as an open system by identifying its boundaries, inputs, outputs, stores, and flows.
2. Compare and contrast the different types of water stores (e.g., interception, surface storage, soil moisture, groundwater) within a drainage basin.
3. Explain the key processes of water flow (e.g., overland flow, throughflow, groundwater flow) and their significance in a drainage basin.
4. Evaluate the impact of varying climatic conditions and land use on the inputs and outputs of a drainage basin.

Inquiry Circle

⏱ 50 min·Small Groups

Inquiry Circle: The Carbon Budget Audit

Groups are assigned a specific 'store' (e.g., the oceans). They must research how much carbon it holds, how it enters and leaves the store, and whether it is currently a carbon 'sink' or 'source'.

Prepare & details

Explain how a drainage basin functions as an open system.

Facilitation Tip: During the Collaborative Investigation, assign each group a different drainage basin to research so students see multiple examples of system inputs and outputs.

Setup: Groups at tables with access to source materials

Materials: Source material collection, Inquiry cycle worksheet, Question generation protocol, Findings presentation template

• Analyze
• Evaluate
• Create
• Self-Management
• Self-Awareness

Think-Pair-Share

⏱ 25 min·Pairs

Think-Pair-Share: The Future of Energy

Students compare the carbon intensity of coal, natural gas, and wind power. They discuss with a partner which energy mix is most realistic for the UK to reach 'Net Zero' by 2050 and share their plan.

Prepare & details

Analyze the various inputs and outputs within a drainage basin.

Facilitation Tip: For the Think-Pair-Share activity, provide a short scenario about water management so students apply the open system concept to a real-world problem.

Setup: Standard classroom seating; students turn to a neighbor

Materials: Discussion prompt (projected or printed), Optional: recording sheet for pairs

• Understand
• Apply
• Analyze
• Self-Awareness
• Relationship Skills

Simulation Game

⏱ 45 min·Small Groups

Simulation Game: The Sequestration Game

Students act as government advisors choosing between different carbon capture technologies (e.g., reforestation vs. CCS). They must weigh up the cost, scale, and permanence of each method to create a national strategy.

Prepare & details

Differentiate between different types of water stores and flows within a basin.

Facilitation Tip: In the Simulation activity, circulate with colored markers and sticky notes to help students adjust their models as they test different precipitation and infiltration rates.

Setup: Flexible space for group stations

Materials: Role cards with goals/resources, Game currency or tokens, Round tracker

• Apply
• Analyze
• Evaluate
• Create
• Social Awareness
• Decision-Making

Teaching This Topic

Teachers find success by starting with a local case study, such as the Thames Basin, to ground the concept. Avoid overwhelming students with too many terms at once; focus first on inputs and outputs before introducing stores and flows. Research shows that students grasp system dynamics better when they manipulate physical or digital models themselves.

What to Expect

Students will confidently identify and explain the four key components of an open system in a drainage basin. They will also trace at least two pathways of water movement, using accurate terminology.

Watch Out for These Misconceptions

Common Misconception

During the Collaborative Investigation, watch for students who confuse the greenhouse effect with the carbon cycle.

What to Teach Instead

Have students create a simple two-column table in their investigation notes. In one column, they list processes from the carbon cycle, and in the other, they list effects of the greenhouse effect. Then, they draw a line between related entries to show how carbon movements influence warming.

Common Misconception

During the Simulation activity, watch for students who think planting trees is the only way to remove carbon from the atmosphere.

What to Teach Instead

Provide a ‘sink sorting’ card set with images and descriptions of different carbon sinks (oceans, soils, CCS). Students must categorize each card as either a natural sink, human-made sink, or temporary storage during the simulation debrief.

Assessment Ideas

Quick Check

During the Collaborative Investigation, circulate and ask each group to orally label three inputs, three outputs, and two stores on their drainage basin diagram before moving to the next part of the activity.

Discussion Prompt

After the Think-Pair-Share activity, ask students to share their responses in a whole-class discussion. Listen for references to specific inputs, outputs, stores, and flows in the Ouse Basin example to assess understanding.

Peer Assessment

After the Simulation activity, have students exchange their concept maps. Each partner checks for the inclusion of all key components (inputs, outputs, stores, flows) and the clarity of connections, providing written feedback on one area for improvement.

Extensions & Scaffolding

• Challenge early finishers to design a water management solution for a drainage basin experiencing increased flooding due to climate change.
• Scaffolding for struggling students: Provide a partially completed diagram with some labels already filled in, such as ‘precipitation’ and ‘evaporation’.
• Deeper exploration: Ask students to research how land-use changes, such as urbanization or deforestation, alter drainage basin behavior and present their findings in a short report.

Key Vocabulary

Drainage Basin	An area of land where all surface water converges to a single point, usually an ocean, river, or lake. It is defined by its watershed or catchment boundary.
Input	Water entering the drainage basin system, primarily as precipitation (rain, snow, hail) and also as groundwater flow from adjacent basins.
Output	Water leaving the drainage basin system, mainly as river discharge (streamflow) and also as evaporation and transpiration from the surface and vegetation.
Store	Water held within the drainage basin at a particular time. This includes water intercepted by vegetation, held on the surface, in the soil, or underground in aquifers.
Flow	The movement of water within the drainage basin system. This includes surface runoff, throughflow (movement through the soil), and groundwater flow.