2024 Edexcel IGCSE Geography 模擬試題連答案詳解

Saltation is the process where small pebbles and stones are bounced along the river bed by the force of the water. Suspension involves fine light material being carried along in the water column. Traction is large boulders rolling along the river bed. Solution is minerals dissolved in water.

1 mark for the correct answer (b).

Steep slopes and impermeable clay soils prevent infiltration, increasing rapid surface runoff (overland flow) into the river channel. This leads to a rapid rise in discharge and a short lag time. Permeable bedrock, dense forest cover, and low drainage density all increase infiltration or delay flow, resulting in a longer lag time.

1 mark for the correct answer (b).

Longshore drift occurs when waves approach the beach at an angle determined by the prevailing wind. The swash carries material up the beach at this angle. The backwash then pulls the sediment straight down the beach at a right angle (90 degrees) due to gravity. This process repeats, moving sediment along the coast in a zig-zag pattern.

1 mark for the correct answer (a).

Slumping (or rotational slip) is a type of mass movement where material moves down a slope along a curved slip plane, often triggered by heavy rainfall saturating the clay-rich soil. Soil creep is a very slow downhill movement, rockfall is free-falling debris, and solifluction is the slow downslope flow of saturated soil over permafrost.

1 mark for the correct answer (c).

Tropical cyclones require sea surface temperatures of at least 26.5 degrees Celsius to provide heat and moisture, and sufficient Coriolis force (usually found at least 5 degrees north or south of the equator) to initiate the spinning motion. They cannot form directly on the equator due to a lack of Coriolis force, and strong vertical wind shear would disrupt their development.

1 mark for the correct answer (a).

In a pre-industrial economy, the vast majority of the population is employed in the primary sector (e.g., agriculture, mining, fishing) to meet basic survival needs. As industrialisation occurs, employment shifts towards the secondary and then the tertiary and quaternary sectors.

1 mark for the correct answer (d).

In the Burgess model, the zone immediately surrounding the Central Business District (CBD) is the Zone of Transition (or twilight zone), which contains older housing, light manufacturing, and is often characterized by urban decay before regeneration.

1 mark for the correct answer (a).

Overgrazing by livestock is a major human cause of desertification because it removes vegetation cover, leaving the soil exposed to wind and water erosion, which strips away the fertile topsoil. Solar radiation is a natural factor, while drip irrigation and re-forestation are methods used to combat desertification.

1 mark for the correct answer (b).

Human activities like deforestation or urbanization significantly increase river flooding risks. When trees are cut down (deforestation), there is less interception of rainfall by leaves and less water absorbed by roots. Consequently, more water reaches the ground quickly, increasing surface runoff and leading to a rapid rise in river discharge, which triggers flooding.

Award 1 mark for identifying a valid human activity (e.g., deforestation, urbanization/building concrete surfaces, building artificial levees downstream).
Award 1 mark for explaining how this activity increases surface runoff or reduces lag time (e.g., 'reducing interception' or 'creating impermeable surfaces that speed up overland flow').

Longshore drift is the geological process by which sediments such as sand and pebbles are transported along a coastline. This occurs because waves (swash) approach the beach at an oblique angle, carrying material up and along the beach, while the backwash pulls the material straight down the slope of the beach under gravity.

Award 1 mark for mentioning the transport/movement of sediment along the coastline.
Award 1 mark for explaining the mechanism (waves approaching at an angle / swash at an angle and backwash perpendicular/straight down).

In high-income countries, economic development leads to an increase in personal wealth and disposable income. As basic survival needs are met, consumers spend a larger portion of their earnings on services such as retail, tourism, healthcare, and entertainment, driving rapid growth and employment in the tertiary sector.

Award 1 mark for identifying a valid reason (e.g., rise in disposable income, technological advancements, outsourcing of primary/secondary industries).
Award 1 mark for explaining how this leads to growth in tertiary employment or output (e.g., 'meaning people spend more on luxury services' or 'creating new jobs in IT and software development').

Rapid urbanization often outpaces the local government's ability to build infrastructure. This leads to the growth of unplanned informal settlements (slums or shantytowns) where residents lack access to clean piped water, safe sanitation, and electricity, raising the risk of waterborne diseases such as cholera.

Award 1 mark for identifying a valid challenge (e.g., growth of informal settlements, high rates of unemployment, traffic congestion, lack of clean water/sanitation).
Award 1 mark for explaining the impact or consequence of this challenge (e.g., 'which leads to the spread of diseases like cholera' or 'resulting in high levels of air pollution from vehicles').

To reduce the damage caused by seismic waves, engineering modifications can be made to buildings. Common methods include installing rubber dampers or base isolators in the foundations to absorb ground vibrations, using interlocking steel frames (cross-bracing) to prevent collapse, and installing a tuned mass damper (a heavy weight) on the roof to counteract sway.

Award 1 mark for each valid design feature stated, up to a maximum of 2 marks.
- Accept: Base isolators / shock absorbers / rubber bearings in foundations.
- Accept: Steel cross-bracing / reinforced steel frames.
- Accept: Shatterproof glass.
- Accept: Tuned mass dampers (weights on roof).
- Reject: vague answers like 'stronger materials' without specifying how.

Desertification degrades productive dryland ecosystems into desert. This process strips the soil of nutrients and moisture, making agricultural land barren. As a result, crop yields plummet and livestock starve, leading directly to food shortages and severe food insecurity for local communities.

Award 1 mark for explaining the direct impact of desertification on the land (e.g., loss of topsoil, soil erosion, land becoming barren/infertile).
Award 1 mark for linking this directly to food production or availability (e.g., 'meaning crops cannot grow, leading to crop failures and famine').

River rejuvenation occurs when there is a drop in the river's base level (for example, due to a fall in sea level or tectonic uplift of the land). This gives the river renewed kinetic energy, causing it to resume active vertical erosion, cutting deeper into its valley floor and forming features like knickpoints and river terraces.

Award 1 mark for identifying the cause (fall in base level / sea level, or tectonic land uplift).
Award 1 mark for identifying the consequence (river gains energy and resumes active vertical erosion / cuts deeper into its bed).

Wave-cut platforms are formed by marine erosion. High-energy waves erode the base of a steep cliff through hydraulic action and abrasion, creating a wave-cut notch. Over time, this notch deepens until the overhanging cliff face becomes unstable and collapses. As this cycle repeats, the cliff retreats inland, leaving a flat, rocky platform at its base, exposed only at low tide.

Award 1 mark for describing the initial erosion at the cliff base (e.g., wave-cut notch formed by abrasion/hydraulic action).
Award 1 mark for explaining the subsequent collapse and retreat (e.g., 'the unsupported cliff above collapses, and as this repeats, the cliff retreats leaving a flat rocky platform').

Saltation is a transportation process where medium-sized particles like small pebbles or sand are temporarily lifted by the water flow and then bounced or hopped along the river bed. This is a repetitive process where the force of the current is just enough to lift the particle momentarily before gravity pulls it back down.

Award 1 mark for identifying that particles are bounced or hopped along the river bed (1), and 1 mark for explaining that this is caused by the flow or force of the water lifting them temporarily before they drop back down under gravity (1).

Constructive waves have a low frequency and low energy. Their key characteristic is a powerful swash (water moving up the beach) and a very weak backwash (water returning to the sea). Because the swash is stronger than the backwash, sediment is carried up the beach and deposited there, building it up over time.

Award 1 mark for identifying that constructive waves have a strong swash and weak backwash (1), and 1 mark for explaining that this leads to the deposition or movement of sediment up the beach (1).

Tropical cyclones require specific physical conditions to develop, including sea surface temperatures of at least 26.5 degrees Celsius (or 27 degrees Celsius) to provide heat and moisture, and a location at least 5 to 30 degrees latitude north or south of the equator for the Coriolis force to cause the system to spin.

Award 1 mark for each valid physical condition identified, up to a maximum of 2 marks. Acceptable responses include: sea surface temperatures of 26.5 degrees Celsius or higher (1), deep water of at least 60-70m (1), Coriolis force or sufficient distance from the equator (1), low wind shear (1).

In HICs, economic development has led to higher disposable incomes and increased leisure time for the population. Consequently, there is a greater demand for services such as tourism, entertainment, personal care, and financial services, which drives employment and growth in the tertiary sector.

Award 1 mark for identifying a reason (e.g., rising disposable incomes, technological advancements, or deindustrialisation) (1) and a further 1 mark for explaining how this leads to growth in tertiary jobs or demand (1).

As people move from the inner city to the outer edges (suburbs), there is increased pressure on the rural-urban fringe. This results in the loss of greenfield sites and agricultural land to make way for new low-density residential developments, roads, and retail parks, causing habitat fragmentation.

Award 1 mark for identifying an impact on the rural-urban fringe (e.g., loss of green space, increased traffic, loss of habitats) (1) and 1 mark for explaining how suburbanisation causes this (e.g., building new housing estates or infrastructure on greenfield sites) (1).

When young adults leave rural areas for urban centers, it leaves behind an older demographic. This causes a shortage of active, working-age labor in the fields. Consequently, farming becomes less productive, leading to reduced food security and economic decline in the village.

Award 1 mark for identifying a challenge (e.g., shortage of agricultural workers, ageing population, decline in services) (1) and 1 mark for explaining the consequence or implication for the rural community (e.g., lower crop yields, closure of local services) (1).

Vertical erosion is concentrated in the upper course of a river where gravitational energy is high, cutting downward into the river bed to deepen the valley. In contrast, lateral erosion dominates in the middle and lower courses, wearing away the river banks sideways to widen the valley floor.

Award 1 mark for explaining vertical erosion (downward erosion or deepening of the river bed) (1), and 1 mark for explaining lateral erosion (sideways erosion or widening of the river banks) (1).

A wave-cut platform is formed when destructive waves attack the base of a cliff through hydraulic action and abrasion, forming a wave-cut notch. Over time, the notch deepens, leaving the overhanging cliff unsupported until it collapses. As this process of erosion and collapse repeats, the cliff retreats inland, leaving a flat, gently sloping rocky platform at its base.

Award 1 mark for identifying the formation of a wave-cut notch or cliff collapse (1) and 1 mark for explaining how successive cliff retreat leaves behind a flat rock platform at sea level (1).

Physical factors dictate the route precipitation takes to a river channel. Permeability is key: impermeable rocks (such as granite) or saturated clay soils prevent infiltration, forcing water to flow rapidly as surface runoff (overland flow). This results in a short lag time and a high peak discharge (a 'flashy' hydrograph). Conversely, permeable rocks (such as chalk) allow infiltration and percolation, leading to slow baseflow, a long lag time, and a low peak discharge. Relief also plays a major role; steep slopes accelerate surface runoff, shortening the lag time, whereas gentle slopes allow more infiltration. Additionally, drainage basins with dense vegetation cover experience significant interception and evapotranspiration, delaying water movement and reducing total discharge, leading to a flatter hydrograph curve.

Level 1 (1-2 marks): Simple description of one or two factors or hydrograph features, with no clear explanation of the link between them. Level 2 (3-4 marks): Explains how specific physical factors (such as steep slopes or impermeable rock) lead to changes in surface runoff and influence at least one feature of the hydrograph (such as peak discharge or lag time). Level 3 (5-6.5 marks): A detailed analysis of multiple physical factors, linking them directly and accurately to specific hydrograph components (rising limb, peak discharge, lag time) using precise geographical terminology.

The formation of a delta requires specific conditions where river processes meet marine environments. As a river reaches its mouth, its velocity decreases significantly because it enters a static body of water. This loss of energy causes the river to deposit its sediment load. The deposition occurs in three distinct layers: the bottomset beds (fine clay carried furthest), the foreset beds (coarser sediment deposited at an angle), and the topset beds (coarse material deposited on top). In saltwater environments, chemical flocculation occurs, where clay particles clump together due to salt attraction and sink rapidly. Over time, these deposited sediments build up, blocking the main channel and forcing the river to split into smaller channels called distributaries. For a delta to form and persist, marine processes must be relatively weak; a low tidal range and constructive waves are necessary so that the deposited sediment is not transported away by marine currents.

Level 1 (1-2 marks): Basic description of deposition or what a delta looks like, with little or no reference to specific processes. Level 2 (3-4 marks): Explains the reduction in river velocity and the general deposition of sediment, making basic links to the role of sea/lake conditions. Level 3 (5-6.5 marks): Detailed analysis of the interaction between river deposition (including bed layers and distributaries) and marine conditions (flocculation, low tidal range, wave energy) required to form a delta.

Discordant coastlines are defined by their geological structure, where bands of contrasting rock resistance (e.g., hard limestone and soft clay) run perpendicular to the shoreline. Marine erosion processes, such as hydraulic action (air compressed in cracks by waves) and abrasion (waves flinging sediment against the cliff), operate on these cliffs. Because soft rocks have less resistance, they undergo rapid erosion, forming recessed inlets known as bays. In contrast, the harder, more resistant rock bands erode much slower, remaining exposed as headlands. Once this discordant shape is established, it alters marine energy: wave refraction concentrates destructive wave energy on the sides of the headlands, accelerating their erosion (forming caves, arches, and stacks), while wave energy is dissipated in the sheltered bays, leading to deposition and beach formation.

Level 1 (1-2 marks): Simple description of headlands and bays or a basic mention of hard and soft rocks. Level 2 (3-4 marks): Explains how differential erosion works on alternating perpendicular bands of rock to form bays and headlands. Level 3 (5-6.5 marks): Clear and detailed analysis of how the geological structure determines the layout, how specific marine processes drive differential erosion, and how subsequent wave refraction reinforces the headland-bay dynamics.

The locational decisions of high-technology (quaternary) industries are influenced by a combination of factors. Human factors are generally dominant. Access to a highly skilled, university-educated workforce is crucial, which is why high-tech clusters often develop near major research universities (e.g., Silicon Valley near Stanford University, or Silicon Fen near Cambridge). Transport infrastructure is another vital human factor; proximity to international airports and major motorways allows for the rapid transit of high-value, low-bulk components and facilitates executive travel. Physical factors also play an important role. High-tech companies often choose locations with attractive physical environments (pleasant climates, green spaces, and scenic landscapes) to attract and retain highly skilled employees. Furthermore, they require flat, greenfield land on science parks to build modern, low-rise research laboratories and offices.

Level 1 (1-2 marks): Mentions basic factors like 'near roads' or 'needs smart people' without linking them clearly to high-technology sector requirements. Level 2 (3-4 marks): Explains specific human and physical factors, showing clear understanding of why they are attractive to high-tech companies. Level 3 (5-6.5 marks): Comprehensive analysis balancing both human factors (skills, transport, agglomeration) and physical factors (landscape, flat land) with precise geographical reasoning and examples.

The shift toward renewable energy sources (such as wind, solar, and tidal power) presents distinct trade-offs. Environmentally, the primary opportunity is the drastic reduction of greenhouse gas emissions, helping to combat global climate change and reduce air pollution. Economically, renewables provide long-term energy security by utilizing infinite natural resources, reducing reliance on volatile fossil fuel imports, and creating 'green' employment in manufacturing and maintenance. However, significant challenges exist. Economically, the initial capital costs of constructing renewable infrastructure (like offshore wind farms) are exceptionally high. Furthermore, many renewable sources are intermittent (e.g., solar power depends on daylight), necessitating costly investments in energy storage systems or backup conventional power plants. Environmentally, renewable developments can cause localized damage, such as wind turbines disrupting bird migration corridors, large-scale solar farms occupying agricultural land, and visual pollution affecting scenic tourist landscapes.

Level 1 (1-2 marks): Simple list of pros and cons of renewable energy with limited depth or separation of economic/environmental aspects. Level 2 (3-4 marks): Explains specific economic and environmental opportunities and challenges, showing a good understanding of renewable technologies. Level 3 (5-6.5 marks): Provides a highly structured and balanced analysis, clearly distinguishing between environmental and economic dimensions, and highlighting the complexities of energy transition (e.g., intermittency versus carbon reduction).

To manage informal settlements, city authorities use different strategies. Large-scale slum clearance and rehousing (top-down) involves demolition and relocating residents to purpose-built concrete high-rises. While this dramatically improves sanitation and safety, it is highly expensive, disrupts established social networks, and often forces residents far from their informal jobs, making it less effective overall. A more successful mid-scale strategy is the 'site-and-service' scheme. Here, the government prepares plots of land with basic infrastructure (clean water, electricity, sewage, paved roads) and leases them to families who build their own homes. This is highly cost-effective and ensures safe living conditions. Lastly, 'self-help' schemes (bottom-up) provide local residents with low-interest loans and construction materials (like timber and bricks) to upgrade their existing dwellings. This empowers communities, preserves social structures, and is very cheap, though it relies heavily on local organization and may not fully resolve deep-seated infrastructure deficits.

Level 1 (1-2 marks): Describes simple improvements like 'putting in pipes' or 'moving people' without evaluating the effectiveness of distinct strategies. Level 2 (3-4 marks): Explains at least two different strategies (e.g., self-help vs. slum clearance) and discusses some of their advantages and disadvantages. Level 3 (5-6.5 marks): Conducts a comparative analysis of the effectiveness of different strategies, noting the trade-offs between cost, social preservation, and infrastructure quality with reference to real-world contexts.

Desertification is a complex process driven by an interplay of physical and human factors. Natural climate variations, such as cyclical droughts, reduce rainfall and dry out the soil, making the vegetation cover fragile. However, human activities are the dominant drivers of permanent land degradation. Rapid population growth in semi-arid regions (such as the Sahel) increases the demand for food, wood, and water. This leads to overcultivation, where land is farmed intensively without fallow periods, stripping nutrients and leaving soil dry and powdery. Overgrazing by livestock removes the remaining vegetation cover, exposing the topsoil to wind and water erosion, while animal hooves compact the soil, preventing water infiltration. Deforestation for firewood removes the deep root systems that bind soil together. Therefore, while natural droughts initiate dry periods, human activities degrade the land's structural capacity to recover, making human factors the primary cause of long-term desertification.

Level 1 (1-2 marks): Basic list of causes of desertification (e.g., cutting trees, lack of rain) without linking them to the physical process of soil degradation. Level 2 (3-4 marks): Explains how human activities (like overgrazing) and natural droughts contribute to desertification, showing some attempt to compare their impacts. Level 3 (5-6.5 marks): A sophisticated analysis that directly addresses the 'extent' command, demonstrating how human pressures compound natural vulnerabilities to drive permanent environmental degradation.

Taking the Arctic as a named fragile environment, global climate change has severe consequences. Ecologically, rising temperatures have caused rapid melting of sea ice and glaciers. This loss of sea ice directly threatens marine ecosystems, disrupting the food chain and removing critical hunting platforms for apex predators like polar bears. Furthermore, the thawing of permafrost alters the landscape, turning tundra into wetlands and releasing vast quantities of stored methane (creating a positive feedback loop that accelerates global warming). Socio-economically, the impacts are equally severe. Indigenous communities, such as the Inuit, face extreme challenges as unstable ice makes traditional hunting routes highly dangerous, threatening their food security and cultural heritage. Additionally, thawing permafrost causes land subsidence, which cracks and collapses critical infrastructure, including roads, houses, and industrial pipelines, costing millions in repairs.

Level 1 (1-2 marks): General statements about global warming (e.g., 'it melts ice' or 'animals lose homes') without applying it in detail to a specific named fragile environment. Level 2 (3-4 marks): Explains specific ecological and socio-economic impacts on a named fragile environment (such as the Arctic or coral reefs), establishing clear links. Level 3 (5-6.5 marks): A comprehensive, well-structured analysis of a named fragile environment, detailing the interconnected nature of ecological damage and its direct knock-on effects on human communities and economic activities.

Measuring at regular, predetermined intervals (such as every 50 cm) across the width of a river channel is an example of systematic sampling. This ensures even coverage across the entire profile without introducing personal bias in point selection.

Award 1 mark for the correct identification of systematic sampling (b).

A clinometer is used in conjunction with two ranging poles placed at a set distance apart to measure the angle of slope (gradient) between different points on a beach, which is required to plot a beach profile.

Award 1 mark for identifying beach profile gradient (a).

A pilot study is a small-scale trial run of the methodology. It allows students to test their survey design, check for any ambiguities, and ensure that the scale used is appropriate before undertaking the main investigation.

Award 1 mark for identifying the correct purpose of a pilot study (a).

Secondary data is information that has already been collected and published by someone else. A digital map showing past land-use changes is a source of secondary data. Questionnaires, pedestrian counts, and environmental quality assessments conducted by the students themselves are primary data.

Award 1 mark for identifying the digital map as secondary data (c).

First, calculate the mean depth: \(\text{Mean depth} = \frac{0.15 + 0.25 + 0.30 + 0.20 + 0.10}{5} = \frac{1.00}{5} = 0.20\text{ m}\). Next, calculate the cross-sectional area: \(\text{Cross-sectional area} = \text{width} \times \text{mean depth} = 5.5\text{ m} \times 0.20\text{ m} = 1.1\text{ m}^2\).

1 mark for showing correct working: summing the depths and dividing by 5, then multiplying by 5.5 (e.g., \(\frac{1.00}{5} \times 5.5\) or \(0.20 \times 5.5\)). 1 mark for the correct final answer of \(1.1\text{ m}^2\) (or \(1.1\)).

First, calculate the total number of pedestrians counted: \(135 + 85 + 55 + 25 = 300\). Next, calculate the percentage counted at Site 1: \(\frac{135}{300} \times 100 = 45\%\).

1 mark for showing correct working, including the total of 300 (e.g., \(\frac{135}{300} \times 100\)). 1 mark for the correct final answer of \(45\%\) (or \(45\)).

First, sum all the pebble measurements: \(4.2 + 5.8 + 3.1 + 7.4 + 2.9 + 6.3 + 5.0 + 4.5 = 39.2\text{ cm}\). Next, divide the total sum by the number of pebbles (8): \(\text{Mean} = \frac{39.2}{8} = 4.9\text{ cm}\).

1 mark for showing correct working, sum of values divided by 8 (e.g., \(\frac{39.2}{8}\)). 1 mark for the correct final answer of \(4.9\text{ cm}\) (or \(4.9\)).

Identify the maximum and minimum decibel values from the dataset: \(\text{Maximum} = 81\text{ dB}\), \(\text{Minimum} = 49\text{ dB}\). Calculate the range by subtracting the minimum from the maximum: \(\text{Range} = 81 - 49 = 32\text{ dB}\).

1 mark for identifying the correct maximum and minimum values and setting up the subtraction (e.g., \(81 - 49\)). 1 mark for the correct final answer of \(32\text{ dB}\) (or \(32\)).

Using a digital flow meter is more reliable because it can be placed at a specific, standardized depth (typically 0.6 of the total depth from the surface), which represents the average velocity of the river channel. In contrast, the float method (such as timing an orange peel over a set distance) only measures surface velocity. Surface velocity is highly susceptible to external factors such as wind resistance and surface turbulence, which can artificially speed up or slow down the float. Therefore, the digital flow meter reduces external variables, leading to more accurate and repeatable data.

Award 1 mark for identifying a valid reason why the flow meter is more reliable (e.g., measures below the surface / at a standardized depth, avoids wind interference, or avoids being trapped by debris). Award a second mark for explaining how this improves the accuracy of the measurement (e.g., the float is affected by wind and surface friction which skews results, whereas the flow meter measures actual average water flow speed). Award a third mark for explaining the overall impact on the reliability of the enquiry (e.g., this ensures data is consistent across different sample sites, allowing for valid comparisons of velocity down the river's course).

Systematic sampling involves choosing sampling sites at regular, fixed intervals (e.g., every 250 metres) along the transect line. This is advantageous because it completely removes subjective student bias, preventing students from choosing sites that look particularly clean or dirty. Furthermore, it ensures an even and continuous coverage across the entire transition from the CBD to the rural-urban fringe. This allows any gradual changes or patterns in environmental quality to be clearly identified and plotted on a graph, which might be missed if random sampling clustered sites in only a few zones.

Award 1 mark for identifying a valid advantage of systematic sampling (e.g., removes user bias, ensures even coverage, or allows clear patterns to be plotted). Award a second mark for explaining how this is achieved along the transect (e.g., by sampling at fixed, regular intervals such as every 250 metres). Award a third mark for linking this to the reliability/validity of the conclusions (e.g., this ensures that the full gradient of urban change is represented without gaps, allowing for a valid analysis of how environmental quality changes with distance from the CBD).

An effective response should evaluate specific primary data collection methods (such as measuring channel width, depth, velocity, or bedload size) and assess how reliable the data collected actually was.

Key areas for evaluation:
1. **Channel Width and Depth:** Measuring tape must be kept taut and perpendicular to the river banks. Depth should be measured at regular intervals (e.g., every 10% of width) using a ruler or wading rod. Potential errors include the ruler sinking into soft sediment or water piling up against it.
2. **Velocity:** Using a flow meter is generally more reliable than using floats (e.g., dog biscuits or oranges), which can get caught in eddies or affected by wind. However, flow meters can fail if vegetation gets clogged in the impeller.
3. **Bedload Analysis:** Measuring the longest axis with calipers and assessing roundness using a Powers' Scale of Roundness. This is subjective and prone to operator bias, which can be minimized by having the same person assess roundness across all sites.
4. **Reliability Improvements:** Reliability is increased by repeating measurements (e.g., three velocity readings per site to calculate a mean), using systematic sampling, and conducting pilot studies.

**Level Descriptors:**

* **Level 1 (1-3 marks) - Low:**
* Demonstrates isolated knowledge of river fieldwork methods (e.g., states that a tape measure was used for width).
* Very limited or no evaluation of reliability; descriptions are simple and general.
* Frequent errors or gaps in geographical vocabulary.

* **Level 2 (4-6 marks) - Medium:**
* Demonstrates good knowledge of specific fieldwork methods (e.g., flow meter for velocity, caliper for bedload).
* Evaluates some strengths and weaknesses of the methods used, showing awareness of potential sources of error (e.g., operator error, sediment interference).
* Begins to construct a balanced argument regarding overall reliability, with some structure and appropriate geographical terminology.

* **Level 3 (7-8 marks) - High:**
* Demonstrates detailed and precise knowledge of a range of primary data collection methods.
* Offers a balanced and critical evaluation of reliability, distinguishing between systematic and random errors (e.g., comparing float vs. flow meter, subjectivity in bedload assessment).
* Directly addresses how reliability impacts the validity of the final geographical conclusions.
* Well-structured response with excellent use of geographical terminology and a clear, logical conclusion.

An effective response should evaluate how both quantitative and qualitative methods complement each other, offering a more complete and valid picture of urban environmental variations.

Key areas for evaluation:
1. **Quantitative Data (e.g., Decibel Levels, Pedestrian Counts):**
* *Strengths:* Highly objective, easily measured, allows for direct statistical analysis, mapping, and comparison across multiple sites.
* *Limitations:* Lacks human context; a high decibel reading does not distinguish between negative noise (traffic congestion) and positive noise (street music or children playing).
2. **Qualitative Data (e.g., Environmental Quality Surveys (EQS), Field Sketches):**
* *Strengths:* Captures human perception, aesthetics, and the overall 'feel' or safety of an urban area, which numbers cannot easily represent.
* *Limitations:* Subjective and prone to observer bias; different researchers may score the same area differently depending on their personal standards.
3. **The Value of Integration:** Combining both techniques (e.g., overlaying EQS scores with noise levels) allows researchers to ground-truth numerical data and understand the underlying reasons behind urban disparities, leading to more robust conclusions.

**Level Descriptors:**

* **Level 1 (1-3 marks) - Low:**
* Identifies examples of quantitative and qualitative data (e.g., decibel levels, questionnaires).
* Provides simple descriptions of what they measure but lacks evaluation of their usefulness.
* No clear structure or use of geographical vocabulary.

* **Level 2 (4-6 marks) - Medium:**
* Explains the differences between quantitative and qualitative methods in an urban context.
* Evaluates some strengths and weaknesses of both data types (e.g., objectivity of numbers vs. subjectivity of surveys).
* Begins to explain how combining them provides a more complete geographical picture, though the argument may be unbalanced.

* **Level 3 (7-8 marks) - High:**
* Provides a highly critical and balanced evaluation of both data types, showing deep understanding of objectivity and subjectivity.
* Clearly demonstrates how combining the two methods overcomes the limitations of using either in isolation (e.g., using qualitative data to explain anomalies in quantitative trends).
* Well-structured response with precise geographical terminology and a logical, well-supported conclusion.

Desertification is driven by both human and physical factors. Prolonged periods of drought (option B) is a natural climatological event, making it a physical cause. Overgrazing (A), fuel wood gathering (C), and poor irrigation techniques (D) are human activities that degrade land.

Award 1 mark for identifying the correct physical cause (B). Any other option selected receives 0 marks.

To find the percentage increase, calculate the difference between the final and initial values, divide by the initial value, and then multiply by 100.
1. Find the difference: \(15,600 - 12,000 = 3,600\) hectares.
2. Divide by the initial value: \(\frac{3,600}{12,000} = 0.3\).
3. Multiply by 100 to get the percentage: \(0.3 \times 100 = 30\%\).

Award 1 mark for correct working:
- \(\frac{15,600 - 12,000}{12,000} \times 100\) OR \(\frac{3,600}{12,000} \times 100\)

Award 1 mark for the correct final answer:
- 30% (accept 30)

To describe the trend, identify the overall direction of change (an increase from 2015 to 2022) and note any anomalies or temporary fluctuations (the decrease in 2020).

Award 1 mark for describing the overall increasing trend:
- Remittances generally increased / grew over the period (accept use of data, e.g., rose from $410bn to $530bn).

Award 1 mark for identifying the temporary dip/anomaly:
- There was a temporary decrease in 2020 (to $470 billion) / the growth was not continuous because of a decline in 2020.

To calculate the range, identify the maximum and minimum values in the data set and find the difference between them.
- Maximum value (Country A) = 0.850
- Minimum value (Country C) = 0.410
- Range = \(0.850 - 0.410 = 0.440\) (or 0.44)

Award 1 mark for correct working:
- Identify highest and lowest values and show subtraction: \(0.850 - 0.410\)

Award 1 mark for the correct final answer:
- 0.44 (accept 0.440 or 0.44)

Way 1: Deforestation reduces the amount of vegetation that can transpire moisture back into the atmosphere. This significantly lowers local evapotranspiration rates (1 mark), which leads to a reduction in relative humidity and localized rainfall levels (1 mark). Way 2: The removal of tree canopy cover leaves the ground surface directly exposed to solar radiation. This increases soil and surface-level air temperatures during the day (1 mark), resulting in higher local temperature extremes (1 mark).

Award 1 mark for identifying a valid process/change, and 1 mark for its further explanation of how it impacts the climate, up to a maximum of 2 marks per way. Way 1 (Max 2 marks): 1 mark for identifying a hydrological change (e.g., reduced transpiration, loss of interception). 1 mark for linking this to a climate outcome (e.g., lower humidity, decreased rainfall, drought conditions). Way 2 (Max 2 marks): 1 mark for identifying a thermal change (e.g., loss of canopy shade, direct exposure to sunlight, changes in albedo). 1 mark for linking this to a climate outcome (e.g., increased average temperatures, greater daily temperature ranges).

Reason 1: Developing countries generally have a lower cost of living and less stringent minimum wage laws, allowing TNCs to hire workers for much lower wages than in developed nations (1 mark). This lowers overall production costs and increases profit margins (1 mark). Reason 2: Governments in developing nations frequently establish Special Economic Zones (SEZs) or offer tax holidays to attract foreign investment (1 mark). This reduces the tax burden and operating costs for the TNC, making production highly profitable (1 mark).

Award 1 mark for identifying a valid reason/factor, and 1 mark for its explanation showing how it benefits the TNC, up to a maximum of 2 marks per reason. Reason 1 (Max 2 marks): 1 mark for identifying a labor advantage (e.g., low labor costs, large/unskilled labor pool). 1 mark for linking this to the TNC benefit (e.g., reduction in manufacturing overheads, increased global competitiveness). Reason 2 (Max 2 marks): 1 mark for identifying a governmental or physical advantage (e.g., cheap land, low environmental regulations, tax incentives, Special Economic Zones). 1 mark for linking this to the TNC benefit (e.g., ease of setting up factories, reduced start-up and operational costs).

To assess the effectiveness, students should compare both strategies: 1. Top-down strategies (like the Great Green Wall) have the advantage of massive scale, political backing, and significant international funding. However, as shown by the low 20-30% survival rate, they often fail because they do not engage local people, struggle with maintenance in harsh desert conditions, and require immense capital. 2. Bottom-up strategies (like FMNR) are highly cost-effective ($40/hectare) and extremely successful at a local scale (80% survival rate) because they utilize existing ecological systems and give farmers direct ownership of the resources (such as firewood and improved soil fertility). 3. Overall, while top-down strategies are useful for securing global funding and coordinating cross-border policies, bottom-up strategies are far more effective and sustainable in the long term because they directly involve the local communities who manage the fragile environment daily.

Level 1 (1-2 marks): Demonstrates isolated knowledge and understanding of desertification strategies. Mainly descriptive, copying points directly from the resource with little or no application or assessment. Level 2 (3-4 marks): Demonstrates geographical knowledge and understanding applied to the context. Evaluates both top-down and bottom-up strategies, pointing out advantages and disadvantages of each. Begins to assess effectiveness, though the argument may be unbalanced. Level 3 (5-6 marks): Demonstrates detailed geographical knowledge and balanced understanding. Offers a well-structured assessment comparing the effectiveness of both strategies using both the resource and wider knowledge. Reaches a clear, logical conclusion or judgement on which strategy is more effective and why.

To structure a high-scoring 12-mark response, candidates should discuss both sides of the argument and provide a reasoned conclusion. On one hand, local-scale strategies are highly successful because they use appropriate technology that is cheap and easy for local communities to maintain. For example, in the Sahel region (e.g., Burkina Faso), the construction of stone lines (bunds) along contours reduces runoff, increases water infiltration, and traps fertile soil, significantly improving crop yields. Similarly, 'zai' planting pits retain moisture and compost, restoring degraded land. These bottom-up approaches empower local people and require minimal capital investment. On the other hand, national and international policies address the larger-scale drivers of desertification. The Great Green Wall initiative, backed by the African Union, aims to restore 100 million hectares of degraded land across the Sahel. This international coordination secures billions of dollars in funding and fosters cross-border scientific collaboration. However, top-down policies often face criticisms of being slow to implement, prone to corruption, or failing to engage local people, which can lead to high tree-mortality rates if planting areas are neglected. In conclusion, local-scale strategies are often more immediately effective and sustainable on the ground due to community ownership. However, they are limited in scale. Therefore, the most effective management of desertification occurs when national and international frameworks provide the funding and political structure to support and scale up these proven local-scale initiatives.

Assessment Objectives breakdown: AO1 (4 marks) - Demonstrate knowledge and understanding of desertification management strategies. AO2 (4 marks) - Apply knowledge to analyze and compare the effectiveness of local vs. national/international strategies. AO3 (4 marks) - Synthesize and evaluate to make a reasoned, balanced judgment. Level 1 (1-4 marks): Demonstrates isolated knowledge of desertification strategies. Mainly descriptive with little or no evaluation. Level 2 (5-8 marks): Explains both local-scale (e.g., bunds, zai) and national/international-scale (e.g., Great Green Wall) strategies with some geographic detail. Attempt at evaluation is made, but may be unbalanced or lack a clear conclusion. Level 3 (9-12 marks): Detailed and balanced evaluation of both scales of management. Well-structured arguments with specific examples (such as Burkina Faso or the Sahel). Offers a clear, reasoned, and nuanced conclusion about how the two scales interact.

To structure a high-scoring 12-mark response, candidates should discuss both sides of the argument and provide a reasoned conclusion. On one hand, local-scale strategies are highly successful because they use appropriate technology that is cheap and easy for local communities to maintain. For example, in the Sahel region (e.g., Burkina Faso), the construction of stone lines (bunds) along contours reduces runoff, increases water infiltration, and traps fertile soil, significantly improving crop yields. Similarly, 'zai' planting pits retain moisture and compost, restoring degraded land. These bottom-up approaches empower local people and require minimal capital investment. On the other hand, national and international policies address the larger-scale drivers of desertification. The Great Green Wall initiative, backed by the African Union, aims to restore 100 million hectares of degraded land across the Sahel. This international coordination secures billions of dollars in funding and fosters cross-border scientific collaboration. However, top-down policies often face criticisms of being slow to implement, prone to corruption, or failing to engage local people, which can lead to high tree-mortality rates if planting areas are neglected. In conclusion, local-scale strategies are often more immediately effective and sustainable on the ground due to community ownership. However, they are limited in scale. Therefore, the most effective management of desertification occurs when national and international frameworks provide the funding and political structure to support and scale up these proven local-scale initiatives.

Assessment Objectives breakdown: AO1 (4 marks) - Demonstrate knowledge and understanding of desertification management strategies. AO2 (4 marks) - Apply knowledge to analyze and compare the effectiveness of local vs. national/international strategies. AO3 (4 marks) - Synthesize and evaluate to make a reasoned, balanced judgment. Level 1 (1-4 marks): Demonstrates isolated knowledge of desertification strategies. Mainly descriptive with little or no evaluation. Level 2 (5-8 marks): Explains both local-scale (e.g., bunds, zai) and national/international-scale (e.g., Great Green Wall) strategies with some geographic detail. Attempt at evaluation is made, but may be unbalanced or lack a clear conclusion. Level 3 (9-12 marks): Detailed and balanced evaluation of both scales of management. Well-structured arguments with specific examples (such as Burkina Faso or the Sahel). Offers a clear, reasoned, and nuanced conclusion about how the two scales interact.