I4 through I7 DESCRIPTION:

 

Gridded fields of water stress indicators based on the ratio of human water use (sum of domestic, industrial and agricultural = DIA, in km3 per year) to renewable water resources (Q) for 1995 (in km3 per year) at 30 minute (latitude by longitude) resolution. Sectoral water use statistics were from WRI (1998). Domestic water demand was computed on a per capita basis for each country and distributed geographically with respect to the 1-km total population field (Vorosmarty et al., 2000). Industrial usage was applied in proportion to urban population. Country-level irrigation withdrawals were distributed over irrigated lands (aggregated from Doll and Siebert, 2000) based on estimated irrigation need (see Irrigation water use metadata). Irrigation need was computed as the difference between potential evapotranspiration (PET, which represents the crop water requirements under optimal conditions) and actual evapotranspiration (AET, see Irrigation water use metadata for details). Grid-based aggregates at 30 resolution were then determined for agricultural plus domestic plus industrial water demand. Discharge (Q) was computed as flow-accumulated composite runoff (Fekete et al., 2002) along a 30-min (latitude by longitude) digital river network (Fekete et al., 2001). A ratio of 0.4 or greater indicates conditions of water stress (Vorosmarty et al., 2000; UN 1997).

 

DOWNLOADABLE FILES:

 

(I4) Relative_water_stress.asc = ratio of DIA/Q, representing the proportion of renewable water resources that are being withdrawn for human use. The value 9999 represents areas where there is water demand but no water supply (hence the RWSI becomes undefined) The value -9999 represents no data. Primary source: Vorosmarty et al.(2000).

(I5) rwsi-01.asc through rwsi-12.asc= monthly ratios of DIA/Q, representing the proportion of renewable water resources that are being withdrawn for human use at a monthly time-step. Primary source: Vorosmarty et al.(2000).

(I6) Water_reuse.asc = ratio of flow-accumulated DIA/Q, representing the degree reuse of water as it flows from upstream to downstream. Primary source: Vorosmarty et al.(2000).

(I7) wri-01.asc through wri-12.asc = monthly ratios of flow-accumulated DIA/Q, representing the degree reuse of water as it flows from upstream to downstream at a monthly time-step. Primary source: Vorosmarty et al.(2000).

 

 

REFERENCES:

 

Döll, P., Siebert, S. (2000): A digital global map of irrigated areas. ICID Journal, 49(2), 55-66.

Fekete, B. M., C. J. Vorosmarty, and R. B. Lammers. 2001. Scaling gridded river networks for macroscale hydrology: Development, analysis and control of error, Water Resources Research, 3 (77): 1955-1967.

Fekete, B. M., C. J. Vorosmarty, and W. Grabs. 2002. High-resolution fields of global runoff combining river discharge and simulated water balances, Global Biogeochemical Cycles, 16 (3): 15-1 to 15-10.

Shiklomanov, I., ed. 1996. Assessment of water resources and water availability in the world: scientific and technical report, State Hydrological Institute, St. Petersburg, Russia.

United Nations, 1997. Comprehensive Assessment of the Freshwater Resources of the World (overview document). World Meteorological Organization, Geneva, Switzerland.

Vorosmarty, C. J., P. Green, J. Salisbury and R. B. Lammers. 2000. Global water resources: vulnerability from climate change and population growth, Science, 289: 284-288.

World Resources Institute (WRI). 1998. World Resources: A Guide to the Global Environment 1998-99, Washington, DC.

 

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