How do drainage basins work, why do rivers flood, and how can flooding be managed?
Key Idea 1.3: the drainage basins of Wales and the UK, the drainage basin as an open system (inputs, stores, flows and outputs), the storm hydrograph and the factors affecting it, the physical and human causes of river flooding, and the hard and soft engineering used to manage flooding.
A focused answer on Key Idea 1.3 for WJEC GCSE Geography Unit 1: the drainage basin as an open system, the storm hydrograph and the factors affecting it, the physical and human causes of river flooding, and the hard and soft engineering used to manage it.
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What this dot point is asking
This dot point covers Key Idea 1.3 of WJEC Unit 1: the drainage basins of Wales and the UK. You need the drainage basin as an open system (inputs, stores, flows, outputs), the storm hydrograph and the factors that change it, the physical and human causes of flooding, and the hard and soft engineering used to manage it.
The drainage basin system
The storm hydrograph
What changes the hydrograph and causes flooding
Managing flooding
Try this
Q1. What is a watershed? [Knowledge recall]
- Cue. The ridge of high land that forms the boundary of a drainage basin and separates it from the next basin; water on either side drains into a different river.
Q2. Explain why afforestation can reduce flooding. [Short explanation]
- Cue. Trees intercept rainfall on their leaves and take up water through their roots, so less water reaches the ground quickly; this slows surface run-off, lengthens the lag time and lowers the peak discharge, reducing the chance of a flood.
Exam-style practice questions
Practice questions written in the style of WJEC exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
WJEC Unit 1 (Theme 1)4 marksDescribe the features of a storm hydrograph.Show worked answer →
A short data-response describe question, usually with a hydrograph to read. Reward described features, using the resource.
Rising and falling. The rising limb shows discharge increasing after rainfall; the falling (recessional) limb shows it returning to normal.
Peak and lag. The peak discharge is the highest flow; the lag time is the gap between peak rainfall and peak discharge.
Top marks. Identify the rising limb, peak discharge, lag time and falling limb, reading values from the graph if asked.
WJEC Unit 1 (Theme 1)8 marksAssess the use of hard and soft engineering to manage river flooding.Show worked answer →
An assess/extended question (levels marking). Reward a balanced look at both approaches with a supported judgement.
Hard engineering. Dams, flood walls, embankments and channel straightening control floods directly and protect property. They are effective but expensive, can look unnatural, and may shift the flood risk downstream.
Soft engineering. Afforestation, river restoration, floodplain zoning and flood warnings work with natural processes; they are cheaper and more sustainable but slower to act and may not stop a large flood alone.
Judgement. Conclude that a combination, matched to the place (for example flood walls in a city plus afforestation upstream), is usually best, and justify your view.
Related dot points
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A focused answer on Key Idea 1.1 for WJEC GCSE Geography Unit 1: what makes a landscape distinctive, the location and features of upland, lowland and glaciated landscapes in Wales and the UK, and the physical and human factors that shape them, with OS map skills.
- Key Idea 1.2 (rivers): the processes that operate in a river landscape (erosion, transportation and deposition), how the long profile and cross profile change downstream, and the formation of distinctive fluvial landforms such as waterfalls, meanders, ox-bow lakes and floodplains.
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- Key Idea 1.2 (coasts): the processes that operate along a coastline (weathering, mass movement, erosion, transportation and deposition), constructive and destructive waves and longshore drift, and the formation of distinctive coastal landforms of erosion (headlands, bays, caves, arches, stacks) and deposition (beaches, spits and bars).
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- Key Idea 4.2 (Theme 4): managing coastal hazards, the use of hard engineering (sea walls, groynes, rock armour, gabions) and soft engineering (beach nourishment, managed retreat, dune regeneration), and the costs, benefits and sustainability of different coastal management strategies.
A focused answer on Key Idea 4.2 for WJEC GCSE Geography Unit 1 (Theme 4): hard engineering (sea walls, groynes, rock armour, gabions) and soft engineering (beach nourishment, managed retreat, dune regeneration), and the costs, benefits and sustainability of coastal management.
- Key Idea 6.3: water resources and their management, the global pattern of water supply and demand, the causes of water surplus and water deficit (scarcity and stress), the impacts of an inadequate water supply, and the strategies used to manage water resources sustainably.
A focused answer on Key Idea 6.3 for WJEC GCSE Geography Unit 2: the global pattern of water supply and demand, the causes of water surplus and deficit, the impacts of an inadequate water supply, and the strategies used to manage water resources sustainably.
Sources & how we know this
- WJEC GCSE Geography (Wales) specification (3110) — WJEC (2019)