Why can steady rain over several days cause a flood when a short downpour does not?

Because the soil becomes saturated, so later rain runs straight over the surface into the river instead of soaking in.

Why does building houses and roads across a catchment make flooding worse?

Tarmac and roofs are impermeable and drains carry water straight to the river, so discharge peaks sooner and higher.

How can clearing woodland from a catchment increase flood risk?

With fewer trees there is less interception and transpiration, so more rainwater reaches the channel and reaches it faster.

What kinds of impact on people should you be able to give for the flood you studied?

Deaths and injuries, homes and businesses inundated, roads and railways cut, and services such as power or clean water lost.

OCR GCSE Geography A J383

Ecosystems of the Planet

Topic overview Abiotic and biotic components, and how ecosystems interact The world’s biomes: where they are and what they are like Where the tropical rainforests are, and what they are like Where the coral reefs are, and what they are like Rainforest processes and nutrient cycling Two threatened ecosystems: a rainforest and a coral reef

Environmental Threats to Our Planet

Topic overview Climate change through the Quaternary, and since 1000AD The evidence for climate change Natural causes of climate change, and the enhanced greenhouse effect The consequences of climate change The world’s climatic regions and global atmospheric circulation How global circulation produces extreme weather Tropical storms: causes, distribution and frequency A drought caused by El Niño or La Niña

Fieldwork Skills

Topic overview Framing an enquiry question and choosing your methods Presenting, analysing and explaining fieldwork data Concluding, and evaluating the enquiry

Geographical Skills

Topic overview Constructing maps, and reading cross-sections and transects Coordinates, scale, distance and reading information from a map Gradient, contours, spot heights and GIS Choosing, constructing and presenting graphs and charts Reading and interpreting the main graph and chart types Number, area, scale and the relationships between units Proportion and ratio, and measures of central tendency and spread Percentages and percentiles, and designing data collection sheets Reading tables, and describing relationships in bivariate data Trend lines and lines of best fit Predicting from data, and spotting weak statistical presentation Drawing and justifying conclusions from data Interpreting images and written sources, and recognising bias Judging the limits of maps, graphs, statistics and images

Landscapes of the UK

Topic overview The UK’s upland, lowland and glaciated landscapes Geomorphic processes: weathering, mass movement, erosion, transport and deposition River landforms and how they form Coastal landforms and how they form Two UK landscape case studies: a river basin and a coastline

People of the Planet

Topic overview Defining and measuring development The global pattern of development: ACs, EDCs and LIDCs Why development is uneven, and the role of aid A developing or emerging country: its context and economy Rostow’s model and the country’s path of development Cities, megacities and world cities Why urban growth rates differ around the world Rapid urbanisation in poorer countries: causes and effects A major city in a poorer or emerging country

People of the UK

Topic overview The UK’s trade, media and cultural links with the world The UK’s geographical diversity and its inequalities Uneven development within the UK, and the effects of economic growth How the UK’s population structure has changed since 1900 Immigration into the UK in the twenty-first century Urban trends in the UK and their effects A major UK city: its people, challenges and ways of life

UK Environmental Challenges

Topic overview Air masses, the North Atlantic Drift and the UK’s extreme weather A UK flood event: causes, effects and responses How people use, modify and change UK ecosystems The UK’s renewable and non-renewable energy sources Changing UK energy supply and demand, and sustainable use Renewables in the UK, and the future of fossil fuels What shapes the UK’s energy choices

UK Environmental Challenges

A UK flood event: causes, effects and responses

3 things to know
Component 01

Overview

The weather and human causes of a UK flood, from saturated soil and snowmelt to building and woodland clearance, its primary and secondary effects on people and the environment, immediate and long-term responses at local and national scale, the Environment Agency, hard and soft engineering, warning systems, and the Somerset Levels floods of 2014.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Key term

How can snowmelt, building and woodland clearance in a catchment each make a river flood?

Key term

What should you be able to say about the weather that triggered the UK flood you studied?

Key term

How does a sudden thaw of lying snow cause a river to flood?

Questions from this subtopic

Each one with the model answer underneath.

1
What should you be able to say about the weather that triggered the UK flood you studied?
Model answer
How heavy or how prolonged the rainfall or snowmelt was, and which weather system delivered it.
2
Why can steady rain over several days cause a flood when a short downpour does not?
Model answer
Because the soil becomes saturated, so later rain runs straight over the surface into the river instead of soaking in.
3
How does a sudden thaw of lying snow cause a river to flood?
Model answer
Meltwater reaches the channel very quickly across frozen or saturated ground, so discharge rises sharply in a few hours.
4
Why does building houses and roads across a catchment make flooding worse?
Model answer
Tarmac and roofs are impermeable and drains carry water straight to the river, so discharge peaks sooner and higher.
5
How can clearing woodland from a catchment increase flood risk?
Model answer
With fewer trees there is less interception and transpiration, so more rainwater reaches the channel and reaches it faster.
6
What kinds of impact on people should you be able to give for the flood you studied?
Model answer
Deaths and injuries, homes and businesses inundated, roads and railways cut, and services such as power or clean water lost.

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Ecosystems of the Planet

Environmental Threats to Our Planet

Fieldwork Skills

Geographical Skills

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The trade winds drive warm surface water .

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AMore sunspots mean the Sun is giving out more energy.

BMore reaches the Earth and the climate warms.

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