Water Withdrawal

Water Withdrawal Sector

Purpose and Perspective

The purpose of the Water Demand sector is to capture medium- and long-term trends in water withdrawal by major category. Total water withdrawal is the sum of water withdrawal from the industry, agriculture, and domestic/municipal sectors. The efficiency with which the water is used changes with technology and education. The level of aggregation used follows the standard approach used in FAO’s Aquastat classification.

Model Structures and Major Assumptions

  • Water withdrawal for agriculture, industry and municipal/domestic use are the major components of total water withdrawal [1]

  • Domestic and municipal water demand is influenced by population and income [2]

  • Industry water demand is determined by production and its water efficiency [3]

  • Agriculture water demand is determined by the size of the irrigated harvested area and water crop demand [4]

  • We estimate water efficient irrigation cost per hectare based on 2030WRG (2009) [5]

Exogenous Input Variables

  • Base water withdrawal per hectare of irrigated harvested land - Units: Cm/(Ha*Year)

  • Base water withdrawal per ton of livestock production - Units: Cm/Ton

  • Indicated proportion of harvested area irrigated - Units: Dmnl

  • Relative average global water efficiency - Units: Dmnl

  • Water utilization efficiency for harvested yield[crop] - Units: Ton/(Ha*Mm)

Initialization Variables

  • Initial industry water withdrawal per unit of output - Units: Cm/Rlcu

Modeling Details

By way of the subscript [product] water withdrawal is separately calculated for different crop categories. Such amounts are based on averaging water withdrawal within crop categories, and therefore can underestimate the change in water withdrawal due to shifting in varieties within crop categories.

Footnotes and References

[1] FAO (2015). AQUASTAT database. Rome: Food and Agriculture Organization of the United Nations.

[2] OECD (2012). OECD Environmental Outlook to 2050. OECD Publishing.

United Nations World Water Assessment Programme (2015). The United Nations World Water Development Report 2015: Water for a Sustainable World. Paris: UNESCO.

[3] OECD (2012). OECD Environmental Outlook to 2050. OECD Publishing.

United Nations World Water Assessment Programme (2015). The United Nations World Water Development Report 2015: Water for a Sustainable World. Paris: UNESCO.

[4] OECD (2012). OECD Environmental Outlook to 2050. OECD Publishing.

United Nations World Water Assessment Programme (2015). The United Nations World Water Development Report 2015: Water for a Sustainable World. Paris: UNESCO.

[5] 2030WRG (2009). Charting Our Water Future: Economic frameworks to inform decision-making. McKinsey & Company.