Degree of Water Stress by Freshwater Ecoregion

Degree of water stress by ecoregion - where human demand for water outstrips natural supply.

These data were derived by The Nature Conservancy, and were displayed in a map published in The Atlas of Global Conservation (Hoekstra et al., University of California Press, 2010). More information at http://nature.org/atlas.

The water stress indicator calculation is based on a global water balance model, coupled with estimates of water use by sector (agriculture, domestic, and industrial). These data were derived from the WaterGAP model developed by the University of Kassel in Germany (Alcamo et al. 2003; Döll et al. 2003). The WaterGAP model combined precipitation, temperature, the location of reservoirs and lakes, and a water-routing network to produce the estimates of runoff by grid cell at a 0.5-degree resolution. In this model, water use statistics by country and sector were combined with satellite-derived land use data, irrigated area, as well as population density to estimate water use by grid cell. To estimate the water stress index, we aggregated runoff and water use by ecoregion and calculated the ratio of water use to availability. The index does not account for the use of water from alternate sources such as groundwater, desalination, or reuse of wastewater. It also does not provide any information on the water needs of the ecosystem and does not take into account water resources that are deemed unusable or degraded due to pollution. The model assumes all water available as runoff in an ecoregion can be available for human use. Water stress indices provide a sense of where pressure on water resources is high, but they are not substitutes for local data.

These data were derived by The Nature Conservancy, and were displayed in a map published in The Atlas of Global Conservation (Hoekstra et al., University of California Press, 2010).

Data derived from:
Alcamo, J., P. Döll, T. Henrichs, F. Kaspar, B. Lehner, T. Rösch, and S. Siebert. 2003. Development and testing of the WaterGAP 2 global model of water use and availability. Hydrological Sciences Journal 48, no. 3: 317-338.

Döll, P., F. Kaspar, and B. Lehner. 2003. A global hydrological model for deriving water availability indicators: Model tuning and validation. Journal of Hydrology 270: 105-134.