A-Level Geography Past Papers & Drilling (Paper 3): Tropical and Coastal Environments

Question 1

(a) Runoff = 2450 – 1180 = 1270 mm, which is 1270 / 2450 x 100 = about 51.8% of rainfall. (3 marks)

(b) The ratio is 320 / 45 = about 7.1 to 1, so the great majority of the biomass is stored above ground. (3 marks)

(c) The loss rate is 12,000 / 480,000 x 100 = 2.5% a year, and clearing the whole area at that rate would take 480,000 / 12,000 = about 40 years. Rainforest nutrients are held mainly in the biomass rather than the soil: decomposition is rapid, uptake by roots is almost immediate and the litter layer is thin, so once trees are removed the nutrients are flushed away by runoff, soils become infertile quickly and recovery takes decades. (4 marks)

Question 2

Line of argument: each strategy works at a small scale, but with forest being lost at 2.5% a year (around 40 years to clear at that rate) effectiveness depends on enforcement capacity, indigenous land rights and alternative livelihoods.

(1) Protected areas: national parks and indigenous reserves cut fire and illegal logging, yet vague boundaries and weak budgets produce “paper parks”.

(2) Selective logging: choice of trees and long rotations preserve canopy structure, but logging roads open the forest and real damage far exceeds the volume felled, so certification needs independent audit.

(3) Ecotourism: creates alternative income and monetises the forest’s existence value, but carrying capacity is limited and uneven revenue sharing causes conflict.

(4) Evaluation: the most effective package combines protected areas, community tenure and international payments such as carbon credits, with remote sensing to monitor loss; a single tool usually displaces the damage elsewhere. (20 marks)

Question 3

(a) Wave speed = wavelength / period = 96 / 8 = 12.0 m/s. (3 marks)

(b) Wave energy is proportional to wave height squared: (1.8 / 1.2)^2 = 2.25 times; cliff retreat over 40 years is 0.35 x 40 = 14.0 m. (4 marks)

(c) The annual budget is 145,000 – 168,000 = a deficit of 23,000 m3 a year; over 15 years the cumulative deficit is 345,000 m3. Unless outputs fall (for example by stopping offshore sand extraction) or inputs rise (beach nourishment, or coastal defences designed to work with longshore drift), the beach narrows and its protective function declines. (3 marks)

Question 4

Line of argument: hard defences protect high-value assets immediately but shift erosion elsewhere; soft approaches are more sustainable yet costlier to maintain, so the best schemes mix the two.

(1) Hard defences: seawalls and revetments resist wave energy directly and suit ports and built-up areas, but they reflect waves, scour the cliff foot and cause terminal effects that starve beaches; with wave height rising from 1.2 m to 1.8 m the energy rises 2.25 times, so design must allow for that increase.

(2) Soft approaches: nourishment restores the surf zone and dunes with vegetation absorb energy and rebuild habitat, but they need repeat supplies of sand and costs rise with distance.

(3) Sediment budget: the annual deficit of 23,000 m3 (345,000 m3 over 15 years) shows that no scheme works unless the budget is addressed.

(4) Evaluation: the choice depends on coastal type, asset value and budget; a shoreline management plan that combines defences with managed realignment and spatial planning is more sustainable than seawalls alone. (20 marks)

Question 1

Daily transport = 1800 / 365 = about 4.9 m3 a day. The direction is set by the prevailing wind and the angle at which waves approach; groynes and breakwaters interrupt the drift so beaches downstream lose their supply.

Question 2

The annual rate is 1 / 10 = 0.1 events a year, that is about once every ten years. Adaptation could raise floor levels and critical infrastructure, convert low-lying land to flood storage or wetland parks, run storm-surge warning and evacuation systems, and cap development density in the highest-risk zones.