assessment that would pull together all the findings and recommendations was expected to be available in September (see www.nos.noaa.gov), with a final report going to Congress and the president in February, said Don Pryor, a NOAA scientist coordinating the project. The work will be used to develop an action plan by August 2000, but Pryor emphasized that the plan would not necessarily result in regulatory changes. More likely are voluntary incentive programs and adjustments to existing programs ranging from reducing fertilizer application rates to agronomically recommended levels to encouraging application during the growing season as opposed to late fall,
when the fertilizer has time to leach out of the soil, Pryor said. On another front, Rabalais, along with a number of other universities across the Midwest, East Coast, and Louisiana, submitted a proposal to the National Science Foundation in July to treat the entire Mississippi basin and Gulf region as a long-term ecological research site. The project would really dig into the science behind how land use in the agricultural areas of the watershed influences nutrient export and what effect these nutrients have on various phytoplankton and the development of hvDoxia and toxic algal blooms according to John Downing a professor at Iowa State TTniversity in Ames w h i c h
DID YOU KNOW? Colloids matter: In aquatic systems, often 40% to 90% of all trace metals and organic compounds are adsorbed on marine and freshwater colloids. Source: ES&T 1998, 32(19), 2887-2899
is a principal collaborator. "It's rare that one sees agricultural and oceanographic institutions collaborating on a research program," Downing added. —KRIS CHRISTEN
Water shortages loom; technology, creative approaches offer solutions Global water-use efficiency will have to double over the next 25 years if the world's food supply is to keep pace with a growing population, according to a leading expert on world water issues. Many existing technologies and policies that conserve water are underused, other water experts agree. At a recent briefing that highlighted a new WorldWatch Institute book, Pillar of Sand, Sandra Postel, director of the Global Water Policy Project in Amherst, Mass., pointed out that as irrigation-based agriculture has expanded from 40 million hectares in 1900 to more than 250 million hectares today, water sources sustaining this practice have been depleted at alarming rates. As a result the roughly 40% of the global food supply that is produced from irrigated land is jeopardized Postel said Concurrent with the increasing amount of land under irrigation, groundwater has been overpumped to the point where water tables are dropping as much as 1 to 1.5 meters per year in important agricultural areas like northwest India and central and northern China, Postel said. Groundwater also is being depleted faster than nature can replenish it from the Ogallala
aquifer under the western Great Plains, which supplies water to 20% of all irrigated land in the United States, as well as in portions of Pakistan, North Africa, the Middle East, and the Arabian peninsula. "Pretty much anywhere you have sizeable irrigated areas, we're seeing groundwater depletion," Postel said, estimating that as much as 10% of the current global food supply depends on the overpumping of groundwater. Supplemental irrigation and more nonirrigated farming have reduced the groundwater overdraft problem with the Ogallala aquifer, said Herman Bouwer, chief engineer at the U.S. Department of Agriculture's Water Conservation Lab in Phoenix, Ariz. But in other regions where no
DID YOU KNOW? As much as10%of the current global food supply depends on the overpumping of groundwater. Source: Sandra Postel, Global Water Policy Project Amherst, Mass.
additional water sources have been put in place, "It's really frightening to think what's going to happen," Bouwer said. The problem may be more severe than anyone realizes because "unfortunately, there's not a lot of ongoing monitoring of major aquifer systems," said Bill Alley, chief of the U.S. Geological Survey's Office of Ground Water. "It's more of a hidden problem that happens slowly over time, so it tends to get neglected." Many of the world's major rivers, another large source of water for irrigation, also are running dry during extended portions of the year. Often, as in the case of the Colorado River, river water contains dissolved salts, which, if they are not removed, accumulate wherever the water evaporates, primarily in irrigated areas. Salt buildup in the Phoenix and Tucson areas is going to be a longterm problem Bouwer said adding that desalinization facilities likely will be the only way to manage it Compounding the problem is the diversion of an increasing volume of irrigation water to supply growing cities and industries, particularly in developing countries—parts of China, southern India, the Middle East—as well as in portions of the western United
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States. "Pretty much everywhere water is becoming scarce, you see water being shipped out of agriculture to supply cities," where water's value is typically 50 to 100 times greater than in agriculture, Postel said. In areas that share international rivers, few treaties currently exist detailing how the water should be shared. And some of these countries, such as Egypt and Ethiopia, are unilaterally pursuing major water projects that commit them to using even more water—a recipe for tension, Postel said.
Pretty much everywhere water is becoming scarce, you see water being shipped out of agriculture to supply cities, where water's value is typically 50 to 100 times greater than in agriculture. — Sandra Postel Global Water Policy Project To get more output from every liter of water extracted from nature, more efficient sprinklers and drip irrigation—a system of plastic pipes and tubes that delivers water direcdy to plant roots to eliminate evaporation and runoff losses—will have to become more widespread, Postel said. Although this technology has been shown to reduce water use by 30%-70% and increase crop yields by 20%-50%, it is only used on 1% of the world's irrigated land. The main reason for diis lack of widespread use is cost With wat"f^i* cn hf^s^/i t\T QI l ri^ifli^f^fi ppnri o m —
ics have not favored drip irrigation Postel said Thus dit tends to get used on high-value crops in areas where farmers tend to be a bit wealthier" as in Israel and California *>pttin
