A.3 Water scarcity and water quality

The scenario states that the country has major rivers and over 1,400 mm of annual rainfall. This indicates that the physical resource is present in substantial quantities — the water itself is not in short supply.

The limiting factor is that pipelines and treatment facilities were never constructed. People must travel long distances to collect water, which is a classic symptom of inadequate infrastructure, not a shortage of the physical resource itself.

Physical water scarcity occurs when the natural supply is genuinely insufficient. Economic water scarcity occurs when water is physically available but cannot be accessed due to lack of investment in wells, pipes, or treatment plants. Here the constraint is clearly infrastructural, not hydrological.

The correct answer is economic water scarcity caused by inadequate infrastructure to access a physically available supply. The high rainfall and flowing rivers confirm the resource exists; the absence of delivery systems is the problem.

The question asks us to classify the type of water scarcity present when a country has abundant rainfall and rivers but lacks water delivery infrastructure.

This option can be eliminated because the scenario explicitly states there is abundant rainfall and major rivers — there is no evidence of insufficient natural supply or over-extraction depleting those sources.

No drought is mentioned. The scenario describes a situation where water resources are adequate year-round. Drought would imply a temporary deficit in precipitation, which contradicts the high annual rainfall figure given.

The scenario makes no mention of industrial activity reducing available water volumes. The problem is specifically a lack of built infrastructure — pipelines and treatment plants — not industrial withdrawal competing with domestic users.

The only remaining option, economic water scarcity caused by inadequate infrastructure to access a physically available supply, correctly identifies the infrastructure gap as the root cause, consistent with the definition of economic water scarcity.

Drought is defined relative to the normal conditions of a specific location, not against an absolute global threshold. It requires a sustained period (months to years) of below-average precipitation, not just a brief dry spell.

A region normally receiving 1,500 mm per year that receives 900 mm is experiencing drought. A naturally arid region receiving 100 mm per year is NOT in drought — that is its normal condition. This relativity is the critical distinguishing feature.

Aridity is a permanent climatic state of low rainfall. Drought is an abnormal, temporary deficit relative to what is normal for that place. This distinction rules out definitions that describe permanent conditions.

The correct answer is a prolonged period in which precipitation falls significantly below the long-term average for a specific place, capturing both the relative nature and the sustained duration that define drought.

The question tests understanding of the precise definition of drought and its distinction from aridity and other temporary weather phenomena.

This describes an arid climate, not drought. The word 'permanently' immediately signals that this is a climatic condition, not a temporary departure from normal — which is what drought requires.

Again, the word 'permanent' makes this a description of aridity, not drought. Drought is temporary and anomalous relative to a location's own baseline, whereas aridity is the baseline itself.

Seasonal variation is a normal, predictable pattern — not an abnormal deficit. Drought requires a prolonged and significant departure from average, not routine seasonal changes in flow.

A prolonged period in which precipitation falls significantly below the long-term average for a specific place is correct because it captures relativity (below average for that place) and duration (prolonged period), which are the two essential elements of the drought definition.

Vegetation performs two critical functions in a drainage basin's water balance: roots bind soil and channel rainfall into the ground (promoting infiltration), and transpiration from leaves recycles moisture into the local atmosphere, contributing to humidity and rainfall. Both processes help maintain soil water stores.

When livestock strip away plant cover, exposed soil becomes compacted or crusted. Rainwater can no longer infiltrate effectively — instead it runs off the surface rapidly. At the same time, there are fewer plants to transpire moisture back into the air, reducing local humidity. Soil organic matter declines, further weakening the soil's capacity to retain water between rainfall events.

Even if total annual rainfall does not change, the effective moisture available to plants, soils, and groundwater stores declines. This is because more rain is lost as surface runoff rather than being stored. The result is that moderate rainfall deficits — which healthy vegetation could buffer — instead cause drought-like conditions in degraded landscapes.

The correct answer is loss of vegetation cover reduces infiltration and evapotranspiration, diminishing moisture recycling and soil water storage, which accurately describes the mechanism linking overgrazing to drought vulnerability.

The question asks for the mechanism by which overgrazing-driven land degradation intensifies drought, even without a change in rainfall totals.

Overgrazing does not introduce excess nutrients into soil in a way that meaningfully increases evaporation rates. This conflates agricultural fertiliser pollution (a water quality issue) with land degradation — these are separate processes with different mechanisms.

While livestock can compact soil, the stated mechanism — that this prevents water from flowing downstream and increases drought risk — is inaccurate. Soil compaction actually increases surface runoff, but the explanation given confuses cause and effect and is not how land degradation interacts with drought.

The idea that overgrazing removes carbon, lowers atmospheric humidity, and directly reduces precipitation is not an established mechanism within IB Geography. Vegetation loss affects local moisture recycling through evapotranspiration, not through soil carbon's effect on humidity.

Loss of vegetation cover reduces infiltration and evapotranspiration, diminishing moisture recycling and soil water storage correctly identifies the two key mechanisms — reduced infiltration and reduced moisture recycling — linking overgrazing to intensified drought conditions.