A-Level Geography: Advanced Analysis & Case Studies

Front

Critique the applicability of the Demographic Transition Model (DTM) to developing nations.

Back

The DTM assumes economic development is the primary driver of demographic change, often failing to account for LEDCs where mortality decline is driven by medical aid (e.g., vaccination) rather than industrialization. Additionally, some nations experience 'demographic trap' dynamics or stage 5 indicators (ageing) while still economically developing, challenging the linear progression of the model.

Front

Distinguish between 'top-down' and 'bottom-up' hazard management strategies.

Back

**Top-down:** Government-led, large-scale engineering (e.g., dams, levees), expensive, high-tech, often reactive. **Bottom-up:** Community-led, local knowledge, education, affordable (e.g., early warning systems, evacuation drills), often proactive. **Critique:** Top-down offers immediate protection but creates a dependency; bottom-up builds resilience but relies on sustained community cohesion and funding.

Front

Analyze the impact of urban roughness (sky view factor) on the Urban Heat Island (UHI) effect.

Back

Urban canyons with low sky view factors trap outgoing longwave radiation, reducing radiative cooling. Taller buildings increase surface area for heat absorption and re-radiation. However, high-density development also reduces solar gain on street level (shading). The net UHI effect depends on the balance between daytime shading (cooling) and nighttime radiative trapping (warming).

Front

Evaluate how channel roughness affects the relationship between hydraulic radius and velocity.

Back

According to the Manning equation, $V = \frac{R^{2/3}S^{1/2}}{n}$, so velocity is directly proportional to hydraulic radius to the power of 2/3 and inversely proportional to channel roughness ($n$). Higher roughness increases friction and therefore reduces velocity for a given hydraulic radius, so a rougher channel must have a larger hydraulic radius or greater depth to maintain the same flow.

Front

Compare the hydrological impacts of afforestation versus deforestation on a drainage basin.

Back

Afforestation increases interception (canopy storage), infiltration via root systems (macropores), and evapotranspiration, reducing peak discharge and increasing lag time. **Conversely**, deforestation reduces interception, lowers albedo, decreases transpiration, and often leads to soil compaction, resulting in surface runoff, reduced lag time, and higher peak discharge. **Link:** This exacerbates flood risk downstream.