OxfordAQA A Level Geography: Physical Geography 1 — Revision Notes

Condensed for the final weeks. For the full explanation, use the Physical Geography 1 study guide.

Hazard, risk and perception

A hazard is a natural event with the potential to cause damage; a disaster occurs when it overwhelms a community’s ability to cope — the same event can produce very different outcomes in different places.

Risk = hazard x vulnerability / capacity to cope

Vulnerability depends on poverty, building quality, population density and warning systems. Capacity to cope depends on governance, wealth, infrastructure and preparedness.

Hazard perception shapes response: people may accept risk fatalistically, adapt to it, or seek to dominate it through engineering — the view held determines what management is politically possible.

Tectonic hazards

Margin	Movement	Result
Constructive	Plates diverge	Mid-ocean ridges, shield volcanoes, mild earthquakes
Destructive	Oceanic subducts under continental	Trenches, composite volcanoes, violent earthquakes
Collision	Two continental plates meet	Fold mountains, strong earthquakes, no volcanoes
Conservative	Plates slide past	Powerful earthquakes, no volcanoes

Collision and conservative margins produce no volcanic activity, because no crust is created or destroyed and so no magma is generated.

Primary effects follow directly from the hazard; secondary effects are consequences of those. Questions asking for secondary effects are routinely answered with primary ones.

Why impacts differ between countries — the hazard is the same; the vulnerability differs. Weaker building regulations, less monitoring technology, poorer emergency services, less money for recovery, denser informal settlements, and slower economic recovery.

The hazard management cycle: response → recovery → mitigation → preparedness. And Park’s disaster-response curve models the drop in quality of life and the rate of recovery — the steepness and the recovery time are what differ between countries, which is exactly the comparison questions want.

Risk reduction: prediction (monitoring), protection (engineering), preparation (drills, education), planning (land-use zoning). Note that volcanic eruptions can often be predicted but earthquakes cannot — a frequent question.

Magnitude versus intensity: magnitude (moment magnitude scale) is a property of the event itself; intensity (Mercalli scale) measures the effects at a particular place. A single earthquake has one magnitude but many different intensities, depending on distance from the epicentre and local building quality.

Storm hazards

Tropical storms require sea temperatures above about 27°C to a depth of 60 m, latitudes between 5° and 30° for sufficient Coriolis deflection, low wind shear, and convergence in the lower atmosphere.

Hazards are wind, storm surge (usually the greatest killer), flooding and landslides. Management follows the same four-part structure as other hazards: prediction, preparation, protection and planning.

Hydrology

Drainage basin system: inputs, stores, flows, outputs.

Storm hydrograph — each factor with its reason:

Factor	Shorter lag, higher peak when
Rock	Impermeable — no infiltration
Soil	Saturated — low infiltration capacity
Relief	Steep — faster overland flow
Vegetation	Sparse — less interception
Land use	Urban — impermeable surfaces and drains
Basin shape	Circular — water converges together

Urbanisation is the standard case: impermeable surfaces prevent infiltration and drains deliver water rapidly to the channel, shortening lag time and raising peak discharge — hence urban flash flooding.

Hard engineering (dams, levées, channelisation) is effective but expensive and can shift the problem downstream. Soft engineering (afforestation, floodplain zoning, wetland restoration) is cheaper and more sustainable but less immediately effective. Evaluate on cost, effectiveness, sustainability and social acceptability.

Coastal systems

Erosion: hydraulic action, abrasion, attrition, solution. Transport: longshore drift — waves approach at an angle, swash carries material up the beach obliquely, backwash returns it perpendicular under gravity, producing net movement along the coast.

Landforms: headlands and bays (differential erosion of alternating rock types); caves → arches → stacks → stumps; wave-cut platforms; spits and tombolos from deposition.

Constructive waves (low, long wavelength, strong swash) build beaches; destructive waves (high, short wavelength, strong backwash) erode them.

Sediment cell — a largely closed system of sources, transfers and sinks. This is why coastal management in one place affects another: groynes trapping sediment starve the beach downdrift, causing erosion elsewhere. That knock-on effect is the key evaluation point.

Management: hard engineering (sea walls, groynes, rip-rap) versus soft (beach nourishment, managed retreat, dune stabilisation). Managed retreat is increasingly favoured for cost and sustainability but is socially contentious, since it means abandoning land.

Worked example: why identical magnitude gives different impact

Two earthquakes of magnitude 7.0 occur — one in a high-income country, one in a low-income country.

Building quality:   aseismic design and enforced codes vs unreinforced masonry
Warning systems:    monitoring and public alerts vs none
Emergency response: equipped search and rescue within hours vs days
Recovery:           insurance and reserves vs dependence on international aid

Hazard magnitude is identical; vulnerability and capacity to cope differ — exactly what the risk equation predicts. Naming specific events as evidence is what turns this from a list into a full-mark answer.

Exam traps

• Giving primary effects when asked for secondary.
• Saying volcanoes occur at collision or conservative margins.
• Claiming earthquakes can be predicted.
• Describing a hydrograph without linking shape to basin characteristics.
• Evaluating coastal management without the sediment cell knock-on effect.
• Generic answers without named case studies, dates and figures.
• Confusing magnitude (a property of the event) with intensity (the effects at a place).
• Forgetting that risk depends on vulnerability and capacity to cope, not hazard magnitude alone.

Self-test

1. Which margins have no volcanic activity, and why?
2. Distinguish primary from secondary effects.
3. Why does urbanisation shorten lag time?
4. Explain longshore drift.
5. Why can groynes cause erosion elsewhere?
6. State the risk equation, and explain why two places hit by an identical hazard can suffer very different impacts.
7. State the four conditions required for a tropical storm to form.

Answers: 1. Collision and conservative — no crust is created or destroyed, so no magma is generated. 2. Primary effects are caused directly by the hazard; secondary effects arise as consequences of those primary effects. 3. Impermeable surfaces prevent infiltration and drainage systems deliver water to the channel rapidly, so water reaches the river much faster. 4. Waves approach the shore at an angle so swash carries sediment obliquely up the beach, while backwash returns it perpendicular to the shore under gravity, giving net movement along the coast. 5. They trap sediment moving by longshore drift, so beaches downdrift are starved of material and become more vulnerable to erosion. 6. Risk = hazard × vulnerability ÷ capacity to cope; the hazard itself may be identical, but vulnerability (poverty, building quality, warning systems) and capacity to cope (governance, wealth, infrastructure) differ between places, producing very different outcomes. 7. Sea temperatures above about 27°C to a depth of 60 m; latitudes between 5° and 30° for sufficient Coriolis deflection; low wind shear; and convergence in the lower atmosphere.