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Addressing the world water crisis: ASABE members lead in the challenge.

More than a billion people lack access to safe drinking water. Two and a half billion people live without access to adequate sanitation systems necessary to reduce exposure to water-related diseases. The failure of the international aid community, nations, and local organizations to satisfy these basic human needs has led to substantial, unnecessary, and preventable human suffering. Tens of thousands of people, mostly young children and the elderly, die every day from water-related diseases.

Peter H. Gleick. 2007. The human right to water. Pacific Institute for Studies in Development, Environment, and Security, http:/! See also Gleick, P.H. 1999. The human right to water. Water Policy 1(5): 487-503.

Safe drinking water and sanitation are just two aspects of the current world water crisis. A broader view includes safe, economical food; sustainable water resources for irrigation and domestic supplies; public protection from natural disasters (drought mitigation, flood protection, etc.); and environmental quality protection and enhancement. Included in all of these are the water resource impacts from global climate change. All of these areas are exactly where you will find agricultural and biological engineers at the forefront of technology, research, education, and training. ASABE members are the leaders in all of these efforts.

Getting down to water basics

Human physiological drinking water requirement estimates vary from 2.5 to 4 L (0.7 to 1.0 gal) per day with an additional 100 L (26.4 gal) per day for sanitation, hygiene, and other household requirements. Peter Gleick notes that the average European water use is 200 to 300 L (50 to 80 gal) per day per person, while the North American water use is approximately 500 L (132.1 gal) per day per person. A Bedouin is estimated to require only 20 L (5 gal) per day.

The major water requirement for human existence is food. Food security is likely at the forefront, but often the water required to grow the crops is a neglected or a hidden issue. The world's population reached six billion on October 12, 1999 and is projected to be expanding at 80 to 85 million per year. The world's population is projected to expand to between 7.3 and 10.5 billion by 2050 or nearly 14 billion at the current growth rate. Some experts have predicted nearly 67 percent of the world's population will experience water stress--defined as an annual water volume of less than ~1 ML (264,200 gal) per person--by 2050 about 10 times the current number (~7 percent). That translates into a ratio of one out of six people living with water stress in 2050.

Daniel Renault and ASABE member Wesley Wallender emphasized the need to focus productivity in terms of nutritive value per unit of water rather than just traditional productivity (kg/[m.sup.3] or pounds/acre/inch) or value ($/[m.sup.3] or $/acre/in). They provided an extensive list of the nutritive water productivity of various foods in terms of energy (calories), protein, fat, and calcium.

Food and Agriculture Organization (FAO) of the United Nations uses a basis of 2,700 kcal per person per day for the human nutritive requirement. The values reported by Renault and Wallender varied considerably by commodity or crop. For example, in energy terms the nutritive water productivity varied from 102kcal/[m.sup.3] for bovine meat (beef) to 5,626 kcal/[m.sup.3] (21 kcal/gal) for potato to~2,000 to 4,000 kcal/[m.sup.3] (7.6 to 15.1 kcal/gal) for traditional cereal crops (wheat, corn, and rice). One factor in these data is the relatively low fraction of the available water for crop production that is partitioned to transpiration that is the principle driver for carbohydrate production and eventually economic productivity. Table 1 presents my estimates of the fraction of the water supply for irrigated, rainfed, and dryland agricultural systems that are available for crop transpiration that vary from 10 to 35 percent depending mainly on the agricultural production system. These estimates indicate a great potential for both agronomic and engineering improvement.

Population growth will fuel future municipal and industrial water demands. These also provide agricultural and biological engineers unique challenges to treat and utilize the waste water. Beside population growth alone, increased living standards in now less developed parts of the world will increase water demands both for domestic needs but also for higher protein diets. Affluence is largely not addressed internationally, but it is likely to emerge as a major future factor.

Water is life and energy

With these population growth rates and increased living standards, the demands for energy will increase. In many areas, even within the United States, the water required in power generation is expected to escalate adding additional demands for water transfers from agriculture to municipal and industrial uses. Even the water requirements for biofuels were estimated by the National Research Council by ASABE member Otto C. Doering III and ASABE fellow E.A. Hiler to raise issues that are regional in the United States on water use but more generally national on water quality, through nutrient transport of N and P and resulting impacts like hypoxia (low dissolved oxygen levels) caused by nutrient pollution and erosion from marginal croplands.
Table 1. Estimated fractions of available water (in percent) for
various agricultural production systems.

Category Irrigated Rainfed Dryland
 Agriculture Agriculture Agriculture
 total = 1.0 >800 mm/yr <600 mm/yr
 m/yr (total = (>30 (<24
 40 in./year) in./year) in./year)

Storage & conveyance 30 0 0

Runoff & drainage 15-30 40-50 5-25

Evaporation (from 10-15 30-35 35-45
soil and water)

Transpiration 20-35 15-30 10-25

Modified by the author but largely adopted from Wallace, J. S., and
C. H. Batchelor. 1997. Managing water resource, production. Philos.
Trans. R. Soc. London Ser. B 352:937-947.

[H.sub.2]O and future uncertainties

These water conflicts to meet future water demands will further heighten strife between countries as well as the many experienced now between states within the United States as water scarcities become major political issues. Adding to these concerns are the large uncertainties about global climate change impacts on water resources in both quantity and distribution from increasing emissions of [CO.sub.2] and other greenhouse gases, particulate matter, etc. In addition, climate variability both temporally and spatially adds major difficulties and increased complexity in the management of water resources.

This year's drought in the southeastern United States illustrates even in a nation with advanced water management how quickly states and regions can emerge in a water conflict due to differing state legal or regulatory variations. In the author's home state and city, the only municipal water supply reservoir, Lake Meredith, is at a record low level now. This raises serious hydrologic questions (that many local ASABE members discuss around coffee or the lunch table at work) about public policy. Did the Conservation Reserve Program designed to reduce water and wind erosion from "highly" eroded lands reduce runoff; did the adoption of conservation tillage designed to leave crop residues to protect the soil surface and reduce water and wind erosion cause reduced runoff; or has the increased brush development caused reduced runoff; or did the salt cedar species invasion along the Canadian River reduce river flows by riparian water uptake, etc.? These all simplify to the question, does advanced technology or government policy result in unintended consequences?

Water for the staff of life

Future food needs will require enhanced productivity from irrigated lands, greater production from waterlogged and salinized lands, and more productivity from rainfed and drylands. As the world's population has increased since the 1960s based on FAO data, irrigated land area has also increased such that the per capita irrigated land has remained relatively stable at about 0.045 ha (0.11 acre) per person. In contrast, arable land area per capita has decreased from 0.38 ha (0.94 acre) per person in 1970 to 0.28 ha (0.69 acre) per person in 1990. Worldwide irrigated land was about 263 Mha (597 million acres) in 1996. Irrigated land comprises 15 percent of the arable land in the world and produces 36 percent of the food. Two-thirds of the world's irrigated area is in Asia. Prior to 1980, the growth in irrigated area exceeded the population expansion, but since 1980 irrigated land area has declined per capita and is expected to continue to decline as few large scale irrigation developments are being constructed or planned while many areas are experiencing serious issues with ground water declines.

Aqua-color coded

Water is often denoted as "blue water" or "green water" or even as "virtual water." Blue water is basically the water used or required for domestic, municipal, industrial, environmental, or recreational uses. Green water is generally the water used in crop production and might include the water used in agricultural food processing. Virtual water represents the water (either green or blue) required to produce a food or industrial commodity that is imported. As an example, grain exported from the United States to another country can represent a water amount that the importing country will not require for food production; hence their grain import is an export of green water from the United States, making the grain import have a virtual water import value.

Society leads

ASABE members are actively at the forefront on irrigation technology, watershed modeling, water quality modeling, education, and training worldwide. Many U.S. and international ASABE members are actively engaged in research, teaching, and training on international water issues. ASABE is an international leader in the world's water crisis in its close partnership with the International Commission of Agricultural Engineers (CGIR) as well as other professional organizations.

ASABE member Luis Pereira from ISA, Technical University of Lisbon, Portugal, is the past president of CGIR, active with International Commission on Irrigation and Drainage, and a noted speaker and researcher on water scarcity issues. ASABE member Gerrit Hoogenboom, University of Georgia at Griffith, has developed computer simulation models that have been used extensively during the last 10 to 15 years to predict growth and development and, ultimately, crop yield as a function of local weather and soil conditions and crop management. Hoogenboom has worked with farmers in the African country of Burkina Faso, who like many of their American counterparts, grow sorghum, millet, and corn, but these crops feed humans not animals.


ASABE members James E. Ayars, USDA-ARS, Parlier, Calif., and Eduardo Bautista, USDA-ARS, Maricopa, Ariz.; the author; Dennis Corwin, USDA-ARS, Riverside, Calif.; and Khaled Bali, University of California at Holtville, led a three-day training course on irrigation technology, salinity, water quality, evapotranspiration, and microirrigation for more than 40 scientists from Iraq sponsored by the USDA-Foreign Agricultural Service and U.S. Department of State in Amman, Jordan, in 2007.

ASABE member Steven R. Evett, USDA-ARS, Bushland, Texas, and Ayars are leading an international effort--the Middle East Regional Irrigation Management Information System--as part of the Middle East Peace Initiative ( bringing together participants from Israel, Jordan, Palestinian Authority, and the United States in one of the most water-scarce regions of the world.

ASABE members are leading a training program, the Indo-U.S. Science and Technology Forum Training School on SWAT (Soil and Water Assessment Tool)/ADAPT (Agricultural Drainage and Pesticide Transport) Modeling for Integrated Water Resource Management, in India and Pakistan. ASABE member Jeffrey Arnold, USDA-ARS, Temple, Texas; ASABE member Prasanna H. Gowda, USDA-ARS, Bushland, Texas; and ASABE member Raghavan Srinivasan, Texas A&M University at College Station, Ashvin K. Gosain, Indian Institute of Technology Delhi, and Sandhya Rao, INRM Consultants, are the principal trainers.

These are just a few of the ASABE members leading the research, education, and training on the world water crisis. Many, many others could be mentioned, particularly on drainage and water quality. Practically every agricultural and biological engineering department or USDA-A RS laboratory with a water emphasis has equally impressive accomplishments that are focused on making water use more productive or effective.

The author wishes to acknowledge as source materials and suggest for further information:

Renault, D., and W. W.Wallender . 2000 Nutritional water productivity and diets. Agric. Water Mgmt. 45(3):275-296.

Schnoor, J. L. (Chair), O. C. Doering HI, D. Entekhabi. E.A. Hiler, T. L. Hullar, G. D. Titman, W. S. Logan (Study Director), N. Huddleston (Communications Officer), and M. Stoever (Sr. Project Assistant). 2007. Water Implications of Biofuels Production in the United States. National Research Council, National Academies Press. Washington. D.C., brief_final.pdf.

Terry A. Howell, Sr.

Terry A. Howell, Sr., ASABE Fellow, is research leader and supervisory agricultural engineer, USDA-ARS, Conservation and Production Research Laboratory, Bushland, Texas, USA;
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Author:Howell, Terry A.
Publication:Resource: Engineering & Technology for a Sustainable World
Date:May 1, 2008
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