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Water withdrawals ease

Key to charts

Certain areas of North America, particularly the southwest of the United States, are already subject to high levels of water stress. Without strong action to reduce water use, this is likely to grow with population increases and shifts in geographic distribution. Local policies, such as water pricing, can significantly affect demand. In addition, international policies related to agricultural trade can strongly affect crop type and therefore, irrigation requirements and water use. Advanced technologies, including biotechnologies to develop more water efficient crops and improve irrigation efficiency, can also have a striking effect. Total water withdrawals decrease under the Policy First and Sustainability First scenarios, where structural changes lead to reduced withdrawals in all sectors across North America.

Under Markets First and Security First conditions, the number of people living in areas with severe water stress increases with population growth although there is a decline in percentage of population affected. Regulatory efforts in Policy First and Sustainability First lead to much more significant decreases in percentages as well as reductions in total numbers (see chart).

Population living in areas with severe water stress: North America (%)

When more than 40 per cent of the renewable water resources of a river basin are being withdrawn for human use the river basin is considered to be under severe water stress. In many of the river basins of the western United States, home to over 100 million people, withdrawals currently exceed these limits.

Source: WaterGAP 2.1 (see technical annex)

Number of people living in areas with severe water stress: North America (million persons)

Source: WaterGAP 2.1 (see technical annex)

Imagine ... increased water stress in mid-continental North America

A number of trends point to increased vulnerability of large areas of mid-continental North America to water stress. These include continued draw down of major aquifers and indications of chemical contamination. At the same time, climate models point to midcontinental drying and lowering of both lake and river levels. An extended hot, dry period starting midway through the 2010s exacerbates these trends. The demand for irrigation water increases at the same time as its availability declines. Transport on the Great Lakes and on major rivers such as the Mississippi, faces disruption.

In the case of ...

Markets First
  • Widespread introduction of water pricing and the removal of agricultural subsidies have already led to the reduction of agriculture in the region, somewhat reducing pressures on water demand.
  • Deals are struck to explore transport of water from the Great Lakes or even more remote sources, to increase water levels in the Mississippi River system.
  • Amounts of goods transported by road increase.
  • Production loss drives more intensive farming elsewhere in the United States, such as California's Central Valley, fuelling water conflicts there. Higher water prices almost everywhere hit marginal businesses and the poor.
  • The region increases imports from abroad to meet domestic shortfalls. This move boosts economies in some producer countries but also makes local and national food security problems worse in situations where land is taken out of the local food production system to meet export demands or quotas.
Policy First
  • Research and legislative efforts are implemented to encourage the introduction of more efficient irrigation methods such as drip irrigation.
  • Processes of reform are accelerated to introduce water pricing and begin to reduce agricultural subsidies.
  • Initiatives are launched throughout the region to enhance rail transport.
  • There is a new push for a strong international climate stabilization treaty.
  • Energy efficiency, renewable energy and forest conservation programmes are promoted and speeded up.
  • Bio-engineered cultivars that yield more 'crop per drop'are researched, developed and introduced faster.
Security First
  • Competing interests in the United States and Canada contest plans for big-scale transfer of water from the Great Lakes.
  • A powerful farm lobby continues to oppose reform in the system of agricultural supports and water subsidies.
  • Knock-on effects of water diversions aggravate long-standing Mexico-United States rows over shared water resources.
  • Falling food exports and rising prices for food commodities on the world market contribute to food shortages, heightening geopolitical tension and giving rise to violence in hotspot areas.
Sustainability First
  • A shift to rain-fed crops and restoration of much of the region to its original tall grass prairie is accelerated.
  • Efforts to enhance rail transport throughout the region are introduced.
  • There is a more rapid shift away from meat-based diets, allowing more efficient land uses for human food rather than animal fodder.
  • Consumer movements call for and galvanize more dispersed, sustainable and localized farming systems.
  • There is a fundamental re-think of lifestyles, economic development and social policy, responding to an emerging awareness that intensive use of capital, water and chemicals by agri-business cannot be sustained, as well as to awareness of parallel problems in other economic sectors and environmental frameworks.

The lessons
Many - if not all - economic systems depend heavily on natural systems but regrettably the latter are too often taken for granted or assumed to be unlimited or easily replaceable. Given the inherent variability and mutability of natural systems, policies should be designed to reduce excessive levels of dependence, especially in the presence of potential threshold effects whereby small changes can prompt catastrophic effects.