Table 1

Contemporary world population living under progressive levels of relative total water demand (DIA/Q). The thresholds and definitions of water stress are as defined by the United Nations (UN) (10). Results shown here contrast national-level summaries (∼102 entries) against grid-based tabulations (∼104 to 105 entries). Indices given are for 1995.

Water stressDIA/Q(unitless)Total population (billions)
Country-levelGrid-based
UNThis study*This study
Low<0.11.721.953.16
Moderate0.1 to 0.22.081.730.38
Medium-high0.2 to 0.41.441.540.37
High>0.40.460.451.76
  • * Total water demand, runoff, and population at 30′ grid spatial resolution were each summed to the national scale, and corresponding aggregates were then computed.