The Water Footprint of Humanity

I have seen the statement that 90% of water used globally is used for agriculture, more and more frequently. This “new” statistic has replaced the often quoted World Health Organization statement that 80% of freshwater used is for irrigation. The WHO number is based on measurement of water withdrawals from rivers and groundwater for irrigation. The 90% number (it is actually 92%) is from a recent paper by Arjen Y. Hoekstra and Mesfin M. Mekonnen of the University of Twente in the Netherlands titled “The Water Footprint of Humanity.” They estimated the consumptive use of rainwater for agricultural production and add that amount of water to groundwater pumping and surface water diversion to examine the consumptive use of water for agriculture.  Thus, the 90% of water used globally refers to an estimate of how much irrigation water and rainfall water is consumed  by crops and agriculture in general.

The Water Footprint has no relationship to the rainwater available and does not relate in any way to the sustainability of surface and groundwater use patterns. In all countries the amount of water in agricultural products accounts for the largest proportion of water used. According to their methods agriculture accounts for 92% of the water footprint, industry 4.4% and domestic use (the water we drink and bath with) accounts for 3.6%.  I’m not at all sure that utilization of rainwater in watering crops a meaningful measurement of water use. It leaves unaddressed sustainability of water use, the importance of (or lack of importance of) the rainfall on woodlands, recharging of groundwater that is not being depleted, stormwater runoff and other rainwater uses. It almost implies an ownership of rainwater that falls in various lands. The purpose of the work was to develop a global water management tool, but does not address the complicated aspects of water that is at times renewable and other times not.

In an attempt to look at water beyond the watershed these two Dutch scientists in a series of studies have attempted to trace the concept they called the Water Footprint, by including data on rainwater use and volumes of water used for human and animal waste assimilation to track waters movement in water-intensive commodities as they move across the globe. By importing food, a country externalizes their water footprint.  The scientists identified the water content of various foods by estimates based on global precipitation, temperature, crop, and irrigation maps and the yield, production, consumption, trade and wastewater treatment statistics for nations. There are assumptions underlying this data on planting and harvesting dates per crop per region, feed composition per animal and country as well. In addition the scientists assumed that industrial water supply are spread according to population densities.

Arjen Y. Hoekstra and Mesfin M. Mekonnen then estimated the water content of all products and determined a trade balance with water content in a product as the measure. Using their methodology the major gross virtual water exporters are the United States, China, India, Brazil, Argentina, Canada, Australia, Indonesia, France and Germany. The scientists note that “all these countries are partially under water stress, which raises the question whether the …choice to consume the limited national (surface and groundwater) resources for export is sustainable and most efficient.” Good question. These scientists were trying to develop a way to look at the global dimension of freshwater resources to try to understand and ultimately solve the most pressing and urgent water problems, addressing the limits on the supply of and contamination of fresh water on the planet, and the ability of the planet to feed themselves. However, their operating framework ignores comparative advantage (French wine) and seems to suggest that water in agricultural products is not properly valued. However, they cannot actually determine what the country limit to agricultural production is because they have not addressed the limits of water supply, and unsustainable use of water.

Let’s look at this from another angle.  All the water on earth is over 4 billion years old. “It's one of the more astonishing things about water — all the water on Earth was … here when Earth was formed, or shortly thereafter…in the first 100 million years or so. There is, in fact, no mechanism on Earth for creating or destroying large quantities of water.” The quote above is from Charles Fishman’s book, The Big Thirst: The Secret Life and Turbulent Future of Water. All the water that ever was or will be on earth is here right now. More than 97% of the Earth’s water is within the in oceans. The remaining 2.8% is the water within the land masses. The land masses contain all the fresh water on the planet. Of the land surface water, 77% is contained in icecaps and glaciers and for all practical purposes is inaccessible in the short run, and on a warmer planet will not be stored in ice. The remaining fresh water is stored primarily in the subsurface as ground water with a tiny fraction of a percent of water is stored as rivers and lakes which are renewed by rainfall.

Only a fraction of water falls as rain each year to make the rivers flow, recharge lakes and groundwater. The water on earth never rests, it is constantly moving within the hydrologic cycle along various complex pathways and over a wide variety of time scales. Water moves quickly through some pathways -rain falling in summer may return to the atmosphere in a matter of hours or days by evaporation. Water may travel through other pathways for years, decades, centuries, or more—the groundwater stored in the Wasia aquifer in Saudi Arabia fell from the atmosphere as rain thousands of years ago. In the Middle East, in California, in India and throughout the planet we are using groundwater faster than it is being recharged. We are using up our stored water reserves to grow food and the water reserves are shrinking. So, that determining the water footprint in the way that Arjen Hoekstra and Mesfin Mekonnen have attempted does not convey the limited time that mankind can continue to use water in the way that we are using water now.  

As of 2010, 783 million people worldwide still relied on unimproved water sources (surface water from lakes, rivers, dams, or unprotected dug wells or springs) for their drinking, cooking, bathing and other domestic activities. In 2004 (the last year for which statistics were available), water, sanitation and hygiene was responsible for 1.9 million annual deaths from diarrhea. Most diarrhea deaths in the world (88%) are caused by unsafe water contaminated by human or animal waste, sanitation or hygiene. In addition, there are estimated to be as many as one billion hungry people in the world, some even in the United States.

The earth has a fixed amount of land and water. Water is complicated by the variability in weather and the variable length of different parts of the water cycle. Precipitation does not fall in the same amounts throughout the world, in a country, or even a region and varies from year to year. We are on a trajectory towards a world where ever increasing numbers of people will not have food security and will starve during drought years.  Farmers in the United States feed 20% of the world’s population on just 10% of the earth’s surface that is how we ended up the largest virtual water exporter. The U.S. agricultural sector is the most successful in the world, but will not be able to meet the world’s projected food demand and we may not want to mine groundwater in California to export Almonds. California might want to drink some of that water. Even if all the world’s farmers adopted conservation-based agricultural production techniques (emphasizing soil health) there are limits to what the earth can reliably produce each year. During a “good” period of temperature and rainfall in the most agriculturally productive areas and the most marginal areas the world’s population and demand for food will grow to exceed the average production and the next drought or the exhaustion of a groundwater aquifer will bring catastrophic consequences. It has always been the nature of man (see the Mayan Empire).

According to the Dutch scientists, over a fifth of the nations are net water importers, they have an external water footprint. Many highly water scarce countries (that can afford it)  are externally water dependent- Kuwait, Jordan, United Arab Emirates, Israel, Yemen, Malta, and Cyprus. Though, not all countries with a large external water footprint are water scarce. One of the interesting observations was that the Netherlands and United Kingdom are net importers of food and thus water.   Arjen Y. Hoekstra and Mesfin M. Mekonnen state “For governments in water-scarce countries such as in North Africa and the Middle East, it is crucial to recognize the dependency on external water resources and to develop foreign and trade policies…” to ensure a sustainable and secure import of water intensive commodities (food). It is not viable to irrigate crops with desalinated water.  According to the US Geological Survey it takes 20 gallons of water (on average) to grow one apple, 4,000 gallons of water to grow one bushel of corn, 11,000 gallons of water to grow one bushel of wheat, 15,000 gallons of water to raise a cow. The Dutch scientists finish by pointing out that China with  a relatively internal water footprint is leasing lands in Africa to secure their food supply and water resources outside their country.

Lake Lanier, Atlanta’s Water and the New Water Reality

Lake Sidney Lanier Reservoir commonly known as Lake Lanier was created by the U.S. Army Corps of Engineers when they constructed the Buford Dam in 1956. According to Charles Fishman in “The Big Thirst” in the 1950’s when Lake Lanier was created the city of Atlanta did not finance a share of the project believing that the city that typically receives almost 50 inches of rain on average a year would never need the water. Atlanta has grown far beyond the expectations of those city fathers and the downstream states of Alabama and Florida have through legal action sought to limit the quantity of water Georgia can retain for their use above Buford Dam, arguing that Florida and Alabama need an adequate flow of water down the Chattahoochee River for power production and drinking water supply in Alabama and for maintaining adequate fresh water flow to the Apalachicola Bay to keep the salinity balance to maintain the estuary ecology, fishing habitats and breeding grounds in Florida. Georgia has single mindedly sought to protect the ability of Atlanta-area water utilities to withdraw unlimited water from the reservoir to meet the unrelenting water demand of the Atlanta metropolitan area for lifestyle water (gardens and green lawns) and life essential water through litigation rather than through conservation and smart planning. A grassroots effort has been launched by the local governments, water authorities, environmental groups, farm groups, industry and others-in short, the ACF stakeholders themselves, to try to achieve equitable water-sharing solutions among stakeholders that balance economic, ecological and social values, while ensuring sustainability for current and future generations.

In the Washington Metropolitan area where two states and the District of Columbia are dependent on the flows of the Potomac River they have the Interstate Commission on the Potomac River Basin, ICPRB, which was authorized by congress in 1940.  ICPRB allocates and manages water resources of the river through the management of the jointly owned (and financed) Jennings Randolph Reservoir (built in 1981), Potomac River Low Flow Allocation Agreement (1978) and the Water Supply Coordination Agreement in 1982 which designated a section of the ICPRB as responsible for allocating water resources during times of low flow and assists in managing water withdrawals at other times. These steps improved reliability of the water supply and ensured maintenance of in-stream flows to meet minimum aquatic habitat requirements. The task of cooperation may be more difficult for Georgia, Alabama and Florida where the distance creates different views of how much water is available and makes it difficult to see that they are joined in a regional watershed.

Back in Georgia- in 1989 after four years of drought, the U.S. Army Corps of Engineers recommended the 20% of the water used to generate hydroelectric power be diverted for Atlanta’s water supply.  Alabama and Florida objected and filed suit against Georgia and the U.S. Corps of Engineers in 1990, arguing that diverting water to Atlanta was environmentally harmful and economically problematic, and that in any case it required congressional approval because the purpose of the Buford Dam was not to supply water to Atlanta. Thought Atlanta has an average annual rainfall of almost 50 inches a year it varies tremendously in 2007 rainfall was less than 32 inches and in 2009 it was over 69 inches.

Drought has always occurred in Georgia. Five times in the past 90 years has Georgia had multi-year droughts that were called “Droughts of the Century.” An analysis of rainfall in Georgia by the U.S. Geological Survey found that  normal and above-average rainfall years occurred or 43% of the time in the past quarter century and drought and severe drought years occurred 57% of the time. If the weather patterns change the problem could be exacerbated, but what has really changed in Georgia to make the problem acute is the population of Atlanta metropolitan area has grown from about 2 million in 1970 to 5.5 million in 2010 without giving any thought to water resources which have not increased and that unrelenting growth impacted water infiltration and hydrology.  While on average there may still be adequate water to sustain the region.  It is clear that Georgia and Atlanta need to be proactive and plan for regular prolonged drought occurring each decade. Georgia has not been at all proactive in protecting the hydrology and water infiltration and regulating consumption of water in the Atlanta metropolitan area, preferring instead litigation in order to obtain more water from Lake Lanier. Georgia has encouraged unsustainable water usage through largely unregulated growth of population, industry and agriculture without any consideration given to historic drought experience and ever increasing demand for water.

Back in 2009 (a year that saw more than 69 inches of rain in Atlanta) as part of the never ending litigation between Georgia, Florida and Alabama Federal District Judge Paul Magnuson ruled that Georgia either had to reach an agreement with her neighbors by July 2012, or return to 1970s water withdrawal levels. Instead of working towards an agreement, Georgia once more chose litigation and the Eleventh Circuit Court of Appeals found that the 1950s legislation approving the construction of the Buford Dam, (which, in turn, created Lake Lanier), anticipated that the metro-Atlanta area would need greater water withdrawal from the lake over time. The Eleventh Circuit Court overruled Magnuson’s 2012 water-sharing deadline. The Eleventh Circuit Court of Appeals sent the case to the Army Corps of Engineers, which controls Buford Dam, telling the group to review Georgia’s water needs against the environmental impact, as well as Florida and Alabama’s water demands.

Alabama and Florida appealed to the U.S. Supreme Court,who declined to hear the case on Monday letting the decision of the EleventhCircuit Court stand. Nonetheless, none of these decisions will create water in Lake Lanier or increase water resources enough to fully supply all needs during a prolonged drought now or a shorter one as demand for water continues to grow. Lake Lanier must be shared and the demand for water during droughts has exceeded the resources available. No matter the outcome of the case Georgia will have to take responsibility for managing its water resources. “More reservoirs” is not a rational response to drought, due to several factors, including the inevitable and large-scale evaporation issue and the cost of construction. Drought is not only part of our lives, but an increasingly, a recurring part of our lives due to the impact of impervious ground cover and increased demand have had on the storage capacity of the watershed. Water usage must be rationalized to the complete hydrological cycle and reliance on water conservation and reuse to stretch existing supplies for use during drought. Finally, litigation does not increase water supplies. Lives, livelihoods, food supply and cost, and life styles are dependent on water as a community, region and nation we need to understand that. 

Water Sustainability and Charles Fishman’s “The Big Thirst”

“The Earth's surface is 71 percent covered in water, and water is the primary force shaping every element of the character of the planet — the geology, the weather, the range and variety of life, the planet's gleaming profile in space…”
…”The total water on the surface of Earth (the oceans, the ice caps, the atmospheric water) makes up 0.025 percent of the mass of the planet — 25/100,000ths of the stuff of Earth.”
“…Scientists don't agree on the precise age of the water on Earth, but it's certainly 4.3 or 4.4 or 4.5 billion years old. It's one of the more astonishing things about water — all the water on Earth was delivered here when Earth was formed, or shortly thereafter…in the first 100 million years or so. There is, in fact, no mechanism on Earth for creating or destroying large quantities of water. What we've got is what's been here, literally, forever…”

The quotes above are from Charles Fishman’s book, The Big Thirst: The Secret Life and Turbulent Future of Water. It is a very elegant and well researched story of how water is used throughout our economies and is the basis of all life and wealth. However, his discussion of water does not clearly focus on the sustainability of our water supply. Mr. Fishman clearly identifies that the water infrastructure is not being adequately maintained in the United States and does not adequately exist in much of the rest of the world. Vast amounts of water leaks from our delivery system, but is not necessarily lost from the water cycle. The real problem is that we are not only mining our water reserves, we are destroying the methods that nature stores fresh water that allows us to have a predictable and reliable supply of water. We as a nation and mankind need to address both problems. The need for water is constant it does not come and go with the weather. The need for water grows with population and wealth. All the ways that water supports our lives are discussed in the book making it well worth reading. There is adequate fresh water in the United States, but it is not delivered uniformly or when we need it. The Mississippi has flooded vast portions of the Midwest while Texas has been having a drought.

Water is our most valuable resource and how we manage its use or allow its abuse may determine the fate of our country and mankind. According to the US Geological Survey about 26 % of the freshwater used in the United States in 2000 came from ground-water sources; the other 74 % came from surface water. Groundwater is an important natural resource, especially in those parts of the country that don't have ample surface-water sources, such as the arid West and in times of drought. Groundwater is a renewable resource, but not in the way that sun light is. Groundwater recharges at various rates from precipitation. The actions of man can impact the recharge rate of groundwater. Changing land use and increasing the amount of impermeable area by paving or building can reduce groundwater recharge.

When you withdraw the groundwater from fine-grained compressible confining beds of sediments and do not replace it, the land subsides. In the pursuit of wealth the ground water in the incredibly fertile Central Valley was pumped to such an extent that the ground subsided more than 75 feet in some places. The area was identified by the research efforts of Joseph Poland as the location of maximum subsidence in the United States due to groundwater mining. Once the land subsides, it looses its water holding capacity and will never recover as an aquifer. Groundwater mining in the Central Valley was believed to have slowed in the past few decades, but it continues as documented by the recent data from the University of California’s Center for Hydrologic Modeling Gravity Recovery and Climate Experiment, GRACE.

The twin satellites of the GRACE program monitor each other while orbiting the Earth, and produce some of the most precise data ever collected on the planet’s gravitational variations. This information is used to determine the changes in ice, snow, groundwater basins, and surface water from season to season and over time. Though the amount of water on Earth is static, the location of the water and its availability for use by man does change. The GRACE program reports that from October 2003 to March 2010, aquifers under the state’s Central Valley were drawn down by 25 million acre-feet — almost enough to fill Lake Mead, California’s and the nation’s largest reservoir. The GRACE program also identified several other areas of the earth where groundwater levels have fallen. These areas include northern India, North Africa, and northeastern China.

California is my usual canary in the mine for water resource management and mismanagement. They have all the resources of knowledge and wealth available to mankind and yet struggle with the politics of addressing their impending water crisis. California local water agencies have invested in water recycling, conservation, groundwater storage and other strategies to stretch supplies, but the demand for cheap water exceeds supply as evidenced by the unsustainable groundwater usage. Year round agriculture that supplies food to the nation (grapes, almonds, avocados, lemons, melons, peaches, plums, and strawberries, oranges, apricots, dates, figs, kiwi fruit, nectarines, olives, pistachios, prunes, and walnuts, garlic, tomatoes, lettuce, cattle and calves) has been made possible by the ample supply of water used for irrigation. The limit to California’s agricultural bounty and the wealth of the ranch owners is water availability.

The water available is a combination of surface water diversions and groundwater pumping. In 2006 before the beginning of the last drought, California used almost 31 billion gallons of water a day for irrigation. This is 351 gallons of water a day for each agricultural dollar earned each year and represents almost 80% of the water used in the state each year (excluding non consumptive power usage). All attempts to reduce water usage have been directed to California residential communities to reduce their per capita water use 20% by 2020. The water that is allocated to agriculture remains cheap water. Food needs to reflect the real cost of the water and the permanent loss of ground water. There is not enough water to support the total level of agriculture in the state. Even as the per capita water usage falls the total water used will grow with the population, but there will be no growth in the water supply for the state and if climate projects are at all true, then there will be less water delivered by snowfall and rain. As documented by GRACE California has continued to make up the short fall in water by using more groundwater than recharges and the groundwater table continues to fall. Water is wealth and life. California is spending its wealth on agriculture in the Central Valley growing cheap walnuts for China and grapes and strawberries for me and when it is gone they will leave behind a desert with water pipes running south to Los Angeles.