GEOGRAPHY & CARTOGRAPHY CALCULATOR
Water Scarcity Index
A precise tool.
What is the Water Scarcity Index & How does it work?
The Falkenmark indicator, also known as the Water Scarcity Index (WSI), measures the amount of renewable freshwater available per person in a given year. It is expressed as a ratio of the per‑capita water supply to a threshold of 1,700 m³ person⁻¹ yr⁻¹, a level below which severe water stress is assumed to occur.
To calculate the index, we first convert the total renewable water resources (usually reported in cubic kilometres per year) into cubic metres, then divide by the population to obtain the per‑capita supply. This value is finally normalised by the 1,700 m³ benchmark, yielding a dimensionless index where values below 1 indicate water scarcity.
Because the WSI is based on renewable resources, it reflects the sustainable capacity of a region’s hydrological cycle. Policymakers use it to identify areas at risk, prioritize water‑saving measures, and assess the impact of climate change on water availability.
WSI = frac{R times 10^{9}}{P times 1700}
R = total renewable water resources (km³ yr⁻¹)
P = population (persons)
1700 = threshold water requirement (m³ person⁻¹ yr⁻¹)
P = population (persons)
1700 = threshold water requirement (m³ person⁻¹ yr⁻¹)
Parameters
Result
—
Frequently Asked Questions
What is the Water Scarcity Index (WSI)?
The WSI measures renewable freshwater availability per person, expressed as a ratio to a threshold of 1,700 m³/person/year below which severe water stress occurs.
How do you convert cubic kilometres to cubic metres?
To convert cubic kilometres to cubic metres, multiply by 1 billion (1 km³ = 1,000,000,000 m³).
What is the threshold for severe water stress in the WSI?
Severe water stress is assumed to occur when the per-capita water supply falls below 1,700 m³/person/year.
How do I calculate the Water Scarcity Index?
Divide the total renewable water resources (in cubic metres) by the population to get the WSI value.
What does a high Water Scarcity Index indicate?
A high WSI indicates abundant freshwater availability per person, while a low index suggests potential water stress or scarcity.
Why is 1,700 m³/person/year used as the threshold?
This threshold was established by Arne Falkenmark to indicate the level of water supply below which severe water stress occurs for basic human needs.
Can I use this index for any country?
Yes, you can calculate the WSI for any country using its total renewable water resources and population data.
Results are for informational purposes only and do not constitute professional advice.