|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
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water resources of a river basin are being withdrawn for human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
|Number of people living in areas
with severe water stress: North America (million persons)
Source: WaterGAP 2.1 (see technical
|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 ...
- 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.
- Research and legislative efforts are implemented to encourage
the introduction of more efficient irrigation methods such as
- Processes of reform are accelerated to introduce water pricing
and begin to reduce agricultural subsidies.
- Initiatives are launched throughout the region to enhance rail
- There is a new push for a strong international climate stabilization
- 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.
- 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.
- 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
- 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.
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