IB Geography A.3.1 Physical and Economic Water Scarcity Notes

Water Scarcity Can Reflect a Physical Shortage or a Failure of Access

1. Water scarcity occurs when usable water cannot meet demand at a particular place and time.
2. Physical water scarcity occurs when withdrawals approach or exceed the renewable water available from rivers, lakes and aquifers.

1. Low rainfall, high evapotranspiration, seasonal supply, drought and over-abstraction can create physical water scarcity.
2. Economic water scarcity occurs when water exists but finance, infrastructure, institutions or political access prevent people from using it safely.
3. Broken pipes, distant sources, limited treatment and unequal service can produce economic water scarcity even in a humid region.
4. The two forms can overlap when a dry region also lacks the money or governance needed to store, treat and distribute water.

Drought Develops Through Linked Atmospheric, Soil and River Deficits

1. Meteorological drought begins when precipitation remains below the expected level for a sustained period.
2. Agricultural drought develops when soil moisture becomes too low for crops or grazing land.
3. Hydrological drought appears later as river flow, reservoir storage and groundwater levels fall.

1. High temperatures can intensify a rainfall deficit by raising evapotranspiration and drying soil faster.
2. Climate variability, persistent pressure patterns and ocean-atmosphere cycles can shift rainfall away from a region.
3. Human actions can deepen the shortage when abstraction, deforestation, soil degradation or reservoir rules reduce available storage.

Drought Impacts Spread Through Food, Energy, Health and Migration Systems

1. Crop failure and livestock losses reduce rural income and can raise food prices beyond the drought area.
2. Low reservoir and river levels can restrict irrigation, hydropower, navigation, industry and urban supply at the same time.
3. Poor water quality may worsen because lower flows provide less dilution for pollutants and warmer water can stress aquatic ecosystems.
4. Households may spend more time or money obtaining water, with the largest burden falling on groups with weak services or few savings.
5. Temporary movement may become longer-term migration when repeated drought removes income, livestock or access to credit.
6. Conflict is possible where users compete for a shrinking supply, but institutions and negotiated allocation can prevent scarcity from becoming violence.
7. Drought risk differs from drought frequency because it also reflects exposure, vulnerability and the capacity to cope.

Water Quantity and Water Quality Set Different Limits on Use

1. Water quantity is the volume available for people, economic activity and ecosystems.
2. Water quality describes whether the physical, chemical and biological condition of water is suitable for a particular use.
3. A river can carry a large volume but remain unusable for drinking when pathogens, nutrients, heavy metals or salinity exceed safe levels.
4. A small supply of clean water can also be inadequate when population, irrigation or environmental demand exceeds its volume.
5. Bangladesh shows the distinction because groundwater may be physically present while naturally occurring arsenic makes some sources unsafe without testing or treatment.
6. Management must protect source quality, control demand and extend affordable access because increasing supply alone may leave contamination or inequality unchanged.