Although 70% of the earth’s surface is covered by water, more than 97% resides in the oceans as salt water that cannot be consumed. The remaining 2.5% exists as fresh water, but only one-third of this water is actually available since the remainder is trapped as ice in the polar caps and glaciers.
Fresh water is renewed by surface evaporation from all bodies of water returning to earth as rain. Underground aquifers, which contain 60 times the volume of surface water found in lakes and ponds, provide another source of fresh water, but the rate at which they are recharged is so slow that they are essentially nonreplaceable.
Water availability will be a serious constraint to achieving the food requirements projected for the near future. It is affected by the following:
Water Stress. Groundwater depletion, overexploitation of rivers, buildup of salts in the soil, silting of reservoirs and canals, increasing water reallocation from agriculture to urban needs, sharing of rivers or other bodies of water between countries, rapid population growth in regions that are already water stressed, and climatic uncertainties all contribute to continued depletion of available fresh water.
Water Control. Floods and droughts make it difficult to maintain consistent agricultural production and influence greatly which crops can be grown. Dams and river diversions rarely offer sustainable solutions, because in most cases they entail drawing more water from freshwater systems that are already stressed.
Depletion of Aquifers. Many cities, industries, and farms have pumped groundwater out of aquifers faster than nature can replenish it. The depletion has spread to many of the world’s most important crop-producing regions, including portions of the United States, India, and China. Mismanagement of this resource could be catastrophic for these regions.
Policies. Most countries, including the U.S., have no official national groundwater policy; this hampers the development of appropriate water and agricultural strategies. Possible changes include privatization of irrigation projects, maintenance of property rights to surface water, creation of property rights for underground water, and others.
Water Price. The simplest method of controlling water use is through a scaled price system that is tied to the demand for water, together with differentials for specific users and increased penalties for overuse. Prices must be realistic and encourage investment in new, efficient technologies and water conservation.
Population Issues. As the world’s population continues to grow, more and more countries will exceed the level that can be fully sustained by available water supplies. We must begin now to:
• Minimize losses due to evaporation and system leakage from handling and distribution systems used by both municipalities and farms.
• Implement a water recovery and recycling program by municipalities, agriculture, and industries.
• Increase productivity by genetic screening of crop varieties for water-efficiency traits and development of new varieties with shorter growing seasons or the ability to grow in cooler periods.
• Develop and implement technologies to create fresh water from wastewater and oceans. Desalination by distillation or membrane filtration, towing icebergs, transporting fresh water in tankers or giant plastic bags, and other technologies may increase drinking water supplies in some specific water-scarce areas of the world, but all are expensive.
• Institute more appropriate water pricing to promote efficient treatment of this precious resource.
• Assure a safe municipal water system and reduce failures related to water loss and inefficiency, to minimize the risk of waterborne disease.
When regions run dry, the results can prove costly to food manufacturers. Since the same water resources are shared by municipalities, industry, and agriculture, curtailment may occur as these resources diminish. When there is a shortage, manufacturers are often the first to lose water use. Closures or production-limiting rationing has already occurred in El Paso, San Antonio, Kentucky, Southern California, China, Pakistan, India, and Thailand.
Food companies need to make long-range plans and invest now to become self-sustained to survive periods of shortfall. These efforts can also send a strong message to the community that the company is a partner in trying to relieve water stress in the region. Companies should:
• Establish management plans for current water use and for development of processes that use less water.
• Replace aged equipment with new technology to eliminate water losses and minimize contamination.
• Meet with the water provider to make long-range plans for shortages and establish time frames for warnings and delivery restrictions.
• Install water-storage facilities and water-purification technology to enable conservation and self-sufficiency during long-term shortages.
• Become politically active in development of water policies. There has been no global assessment of how much water will be required to produce the food supplies needed during the next quarter century, nor whether that water will be available when and where it is needed. Without such assessments, countries will not be able to accurately predict their future food import requirements or prepare for the economic and social disruption that will ensue as farmers lose their water. Food processors are also at the mercy of these factors. When the well runs dry, all of us will be affected.
by Wayne R. Bidlack is Dean, College of Agriculture, California State Polytechnic University, Pomona.