The term Peak Water has been put forward as a concept to help understand growing constraints on the availability, quality, and use of freshwater resources. The clearest definitions of the term were laid out in a 2010 peer-reviewed article in the Proceedings of the National Academy of Sciences by Peter Gleick and Meena Palaniappan.[2] They define peak renewable, peak non-renewable, and peak ecological water. There is a vast amount of water on the planet but sustainably managed water is becoming scarce.[3] An updated assessment was published in August 2011 in the Stockholm International Water Institute's journal.[4] Much of the world's water in underground aquifers[5] and in lakes[6] behaves like a finite resource by being depleted. The phrase peak water sparks debates similar to those about peak oil. The concept has sparked such high interest that The New York Times chose the phrase "peak water" as one of their 33 "Words of the Year" for 2010.[7]
There is concern that the state of peak water is being approached in many areas around the world. Some areas are suffering from peak renewable water, where entire renewable flows are being consumed for human use, peak non-renewable water, where groundwater aquifers are being overpumped (or contaminated) faster than nature recharges them (this example is most like the peak oil debate), and peak ecological water, where ecological and environmental constraints are overwhelming the economic benefits provided by water use.[2] If present trends continue, 1.8 billion people will be living with absolute water scarcity by 2025, and two thirds of the world population could be subject to water stress.[8] Ultimately, peak water is not about running out of fresh water, but about reaching physical, economic, and environmental limits on meeting human demands for water and the subsequent decline of water availability and use.
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The Hubbert curve has gained a high degree of popularity in the scientific community for predicting the depletion of various natural resources. M. King Hubbert created this measurement device in 1956 for a variety of finite resources such as coal, oil, natural gas and uranium.[9] Hubbert's curve was not applied to resources such as water originally, since water is a renewable resource. Some forms of water, however, such as fossil groundwater, exhibit similar characteristics to oil, and overpumping (faster than the rate of natural recharge of groundwater) often results in a Hubbert-type peak. A modified Hubbert curve applies to any resource that can be harvested faster than it can be replaced.[1] Like peak oil, peak water is inevitable given the rate of extraction of certain water systems. A current argument is that growing populations and demands for water will inevitably lead to non-renewable use of water resources.[10]
Fresh water is a renewable resource, yet the world's supply of clean, fresh water is under increasing demand for human activities. The world has an estimated 1.34 billion cubic kilometers of water, but 96.5 percent of it is salty.[11] Nearly 70% of that fresh water is frozen in the icecaps of Antarctica and Greenland. Most of the remainder is present as soil moisture or lies in deep underground aquifers as groundwater not accessible to human use. Less than 1% of the world's fresh water or 0.007% of all water on earth is accessible for direct human use. This is the water found in lakes, rivers, reservoirs and those underground sources that are shallow enough to be tapped at an affordable cost. Only this minuscule amount is regularly renewed by rain and snowfall, and is therefore available on a sustainable basis.
| Total Freshwater Supply | ||
|---|---|---|
| Country | (km^3/yr) | Year |
| Brazil | 8233 | 2000 |
| Russia | 4498 | 1997 |
| Canada | 3300 | 1985 |
| Colombia | 3132 | 2000 |
| USA | 3069 | 1985 |
| Indonesia | 2838 | 1999 |
| China | 2830 | 2008 |
| Peru | 1913 | 2000 |
| India | 1908 | 1999 |
| DR Congo | 1283 | 2001 |
| Venezuela | 1233 | 2000 |
| Bangladesh | 1211 | 1999 |
| Burma | 1046 | 1999 |
| Chile | 922 | 2000 |
| Vietnam | 891 | 1999 |
The amount of available freshwater supply in some regions is decreasing because of (i) climate change, which has caused receding glaciers, reduced stream and river flow, and shrinking lakes; (ii) contamination of water by human and industrial wastes; and (iii) overuse of non-renewable groundwater aquifers. Many aquifers have been over-pumped and are not recharging quickly. Although the total fresh water supply is not used up, much has become polluted, salted, unsuitable or otherwise unavailable for drinking, industry and agriculture.
Water demand already exceeds supply in many parts of the world, and as the world population continues to rise, many more areas are expected to experience this imbalance in the near future.
Agriculture represents 70% of freshwater use worldwide.[13]
Agriculture, industrialization and urbanization all serve to increase water consumption.
The highest total annual consumption of water comes from India, China and the United States, countries with large populations and extensive agricultural irrigation demand for food production. See the following table:
| Country | Total Freshwater Withdrawal (km^3/yr) | Per Capita Withdrawal (m^3/p/yr) | Domestic Use (%) | Industrial Use (%) | Agricultural Use (%) |
|---|---|---|---|---|---|
| India | 645.84 | 585 | 8 | 5 | 86 |
| China | 549.76 | 415 | 7 | 26 | 68 |
| United States | 477 | 1,600 | 13 | 46 | 41 |
| Pakistan | 169.39 | 1,072 | 2 | 2 | 96 |
| Japan | 88.43 | 690 | 20 | 18 | 62 |
| Indonesia | 82.78 | 372 | 8 | 1 | 91 |
| Thailand | 82.75 | 1,288 | 2 | 2 | 95 |
| Bangladesh | 79.4 | 560 | 3 | 1 | 96 |
| Mexico | 78.22 | 731 | 17 | 5 | 77 |
| Russia | 76.68 | 535 | 19 | 63 | 18 |
| Iran | 72.88 | 1,048 | 7 | 2 | 91 |
| Vietnam | 71.39 | 847 | 8 | 24 | 68 |
| Egypt | 68.3 | 923 | 8 | 6 | 86 |
| Brazil | 59.3 | 318 | 20 | 18 | 62 |
| Uzbekistan | 58.34 | 2,194 | 5 | 2 | 93 |
| Canada | 44.72 | 1,386 | 20 | 69 | 12 |
| Iraq | 42.7 | 1,482 | 3 | 5 | 92 |
| Italy | 41.98 | 723 | 18 | 37 | 45 |
| Turkey | 39.78 | 544 | 15 | 11 | 74 |
| Germany | 38.01 | 460 | 12 | 68 | 20 |
India has 20 percent of the Earth's population, but only four per cent of its water. Water tables are dropping fast in some of India's main agricultural areas. The mighty Indus and Ganges rivers are tapped so heavily that, except in rare wet years, they no longer reach the sea.[15]
India has the largest water withdrawal out of all the countries in the world. Eighty-six per cent of that water goes to support agriculture.[14] That heavy use is dictated in large part by what people eat. People in India consume a lot of rice. Rice farmers in India typically get less than half the yield per unit area and they use 10 times more water than their counterparts in China do. Economic development in some ways makes matters worse. As people's living standards rise, they tend to eat more meat. But it takes tremendous quantities of water to raise animals for food. Growing a tonne of grain requires 1,000 tonnes of water. To produce a tonne of beef takes 15,000 tonnes. To make a single hamburger requires around 4940 liters (1,300 gallons) of water[15] A glass of orange juice needs 850 liters (225 gallons) of fresh water to produce.[16]
China, as the most populous country in the world, has the second largest water withdrawal out of all the countries in the world. Sixty-eight per cent of that water goes to support agriculture and its growing industrial base is consuming twenty-six percent.[14] China is facing a water crisis where water resources are over-allocated, inefficiently used, and grossly polluted by human and industrial wastes. One third of China's population lacks access to safe drinking water. Rivers and lakes are dead and dying, groundwater aquifers are over-pumped, uncounted species of aquatic life have been driven to extinction, and direct adverse impacts on both human and ecosystem health are widespread and growing.
In western China’s Qinghai province, through which the Yellow River’s main stream flows, more than 2,000 lakes have disappeared over the last 20 years. There were once 4,077 lakes.[17] Global climate change is responsible for the reduction in flow of the (Huang He) Yellow River over the past several decades. The source of the Yellow River is the Qinghai-Xizang Tibetan plateau where the glaciers are receding sharply.[18]
In Hebei Province, which surrounds Beijing, the situation is much worse. Hebei is one of China's major wheat and corn growing provinces. The water tables have been falling fast throughout Hebei. The region has lost 969 of its 1,052 lakes.[17] About 500,000 people are affected by a shortage of drinking water due to continuing droughts. Hydro-power generation is also impacted.[19] Two large cities - Beijing and Tianjin depend on Hebei Province to supply their water from the Yangtze River. Beijing gets its water via the newly constructed South-North Water Transfer Project.[20] The river originates in a glacier on the eastern part of the Tibetan plateau.
The United States has about 5% (1/20) of the world's population, yet the US uses almost as much water as India (~1/5 of world) or China (1/5 of world) because substantial amounts of water are used to grow food exported to the rest of the world. The agricultural sector in the US consumes more water than the industrial sector, though substantial quantities of water are withdrawn (but not consumed) for power plant cooling systems.[14] There are 36 states in the U.S. in some form of water stress, from serious to severe.
The Ogallala Aquifer in the southern high plains (Texas and New Mexico) is being mined at a rate that far exceeds replenishment—a classic example of peak non-renewable water. Portions of the aquifer will not naturally recharge due to layers of clay between the surface and the water-bearing formation, and because rainfall rates simply do not match rates of extraction for irrigation.[21] The term fossil water is sometimes used to describe water in aquifers that was stored over centuries to millennia. Use of this water is not sustainable when the recharge rate is slower than the rate of groundwater extraction.
In California, massive amounts of groundwater are also being withdrawn from Central Valley groundwater aquifers — unreported, unmonitored, and unregulated.[22] California's Central Valley is home to one sixth of all U.S. irrigated land, and the state leads the nation in agricultural production and exports. The inability to sustain groundwater withdrawals over time may lead to adverse impacts on the region's agricultural productivity.
The Central Arizona Project (CAP) is a 336-mile (541 km) long canal that diverts 489 billion US gallons (1.85×109 m3) a year from the Colorado River to irrigate more than 300,000 acres (1,200 km2) of farmland. The CAP project also provides drinking water for Phoenix and Tucson. It has been estimated that Lake Mead, which dams the Colorado, has a 50-50 chance of running dry by 2021.[23]
The Ipswich River near Boston now runs dry in some years due to heavy pumping of groundwater for irrigation. Maryland, Virginia and the District have been fighting over the Potomac River. In drought years like 1999 or 2003, and on hot summer days the region consumes up to 85 percent of the river's flow.[24]
Turkmenistan, Kazakhstan and Uzbekistan use the most water per capita. See the table below:
| Total Freshwater Withdrawal | Per Capita Withdrawal | Domestic Use | Industrial Use | Agricultural Use | |
|---|---|---|---|---|---|
| Country | (km^3/yr) | (m^3/p/yr) | (%) | (%) | (%) |
| Turkmenistan | 24.65 | 5,104 | 2 | 1 | 98 |
| Kazakhstan | 35 | 2,360 | 2 | 17 | 82 |
| Uzbekistan | 58.34 | 2,194 | 5 | 2 | 93 |
| Guyana | 1.64 | 2,187 | 2 | 1 | 98 |
| Hungary | 21.03 | 2,082 | 9 | 59 | 32 |
| Azerbaijan | 17.25 | 2,051 | 5 | 28 | 68 |
| Kyrgyzstan | 10.08 | 1,916 | 3 | 3 | 94 |
| Tajikistan | 11.96 | 1,837 | 4 | 5 | 92 |
| USA | 477 | 1,600 | 13 | 46 | 41 |
| Suriname | 0.67 | 1,489 | 4 | 3 | 93 |
| Iraq | 42.7 | 1,482 | 3 | 5 | 92 |
| Canada | 44.72 | 1,386 | 20 | 69 | 12 |
| Thailand | 82.75 | 1,288 | 2 | 2 | 95 |
| Ecuador | 16.98 | 1,283 | 12 | 5 | 82 |
| Australia | 24.06 | 1,193 | 15 | 10 | 75 |
Turkmenistan, gets most of its water from the Amu Darya River. The Qaraqum Canal is a canal system that takes water from the Amu Darya River and distributes the water out over the desert for irrigation of its orchard crops and cotton.[25] Turkmenistan uses the most water per capita in the world because only 55% of the water delivered to the fields actually reaches the crops.[14][26]
The two rivers feeding the Aral Sea were dammed up and the water was diverted to irrigate the desert so that cotton could be produced. As a result, the Aral Sea's water has become much saltier and the sea's water level has decreased by over 60%. Drinking water is now contaminated with pesticides and other agricultural chemicals and contains bacteria and viruses. The climate has become more extreme in the area surrounding it.[27]
Saudi Arabia, Libya, Yemen and United Arab Emirates have hit peaks in water production and are depleting their water supply. See the table below:
| Total Freshwater Withdrawal | Total Freshwater Supply | Total Freshwater Shortfall | |
|---|---|---|---|
| Region & Country | (km^3/yr) | (km^3/yr) | (km^3/yr) |
| Saudi Arabia | 17.32 | 2.4 | -14.9 |
| Libya | 4.27 | 0.6 | -3.7 |
| Yemen | 6.63 | 4.1 | -2.5 |
| United Arab Emirates | 2.3 | 0.2 | -2.2 |
| Kuwait | 0.44 | 0.02 | -0.4 |
| Oman | 1.36 | 1.0 | -0.4 |
| Israel | 2.05 | 1.7 | -0.4 |
| Qatar | 0.29 | 0.1 | -0.2 |
| Bahrain | 0.3 | 0.1 | -0.2 |
| Jordan | 1.01 | 0.9 | -0.1 |
| Barbados | 0.09 | 0.1 | 0.0 |
| Maldives | 0.003 | 0.03 | 0.0 |
| Antigua and Barbuda | 0.005 | 0.1 | 0.0 |
| Malta | 0.02 | 0.07 | 0.1 |
| Cyprus | 0.21 | 0.4 | 0.2 |
According to Walid A. Abderrahman (2001), "Water Demand Management in Saudi Arabia", Saudi Arabia reached peak water in the early 1990s, at more than 30 billion cubic meters per year, and declined afterward. The peak had arrived at about midpoint, as expected for a Hubbert curve.[30] Today, the water production is about half the peak rate. Saudi Arabian food production has been based on "fossil water"—water from ancient aquifers that is being recharged very slowly if at all. Fossil water is non-renewable, just as oil is, and it is unavoidable that it has to run out someday. Saudi Arabia has abandoned its self-sufficient food production and is now importing all of its food.[29] Saudi Arabia has built desalination plants to provide about half the country’s fresh water. The remainder comes from groundwater (40%), surface water (9%) and reclaimed wastewater (1%).
Libya is working on a network of water pipelines to import water, called the Great Manmade River. It carries water from wells tapping fossil water in the Sahara desert to the cities of Tripoli, Benghazi, Sirte and others. Their water also comes from desalination plants.[32]
Peak water has occurred in Yemen.[33][34] Sustainability is no longer attainable in Yemen, according to the government's five-year water plan for 2005-2009.[35] The aquifer that supplies Sana'a, the capital of Yemen, will be depleted by 2009. In its search for water in the basin, the Yemeni government has drilled test wells that are 2 kilometers (1.2 mi) deep, depths normally associated with the oil industry, but it has failed to find water. Yemen must soon choose between relocating the city and building a pipeline to coastal desalination plants.[36]
As of 2010, the threat of running out of water was considered greater than that of Al-Qaeda or instability. There was speculation that Yemenis would have to abandon mountain cities, including Sanaa, and move to the coast. The cultivation of khat and poor water regulation by the government were partly blamed.[37]
United Arab Emirates has a rapidly growing economy and very little water to support it. UAE requires more water than is naturally available. They have reached peak water. To solve this, UAE has a desalination plant near Ruwais and ships its water via pipeline to Abu Dhabi.[38]
Water shortage may cause famine in Pakistan.[39][40] Pakistan has approximately 35 million acres (140,000 km2) of arable land irrigated by canals and tube wells, mostly using water from the Indus River. Dams were constructed at Chashma, Mangla, and Tarbela to feed the irrigation system. Since the completion of the Tarbela Dam in 1976 no new capacity has been added despite astronomical growth in population. The gross capacity of the three dams has decreased because of sedimentation, a continual process. Per-capita surface-water availability for irrigation was 5,260 cubic meters per year in 1951. This has been reduced to a mere 1,100 cubic meters per year in 2006. The water shortage will cause a wheat deficit of 12 million tonnes per year by 2012–13.
The quality of drinking water is vital for human health. Peak water constraints result in people not having access to safe water for basic personal hygiene. "Infectious waterborne diseases such as diarrhea, typhoid, and cholera are responsible for 80 percent of illnesses and deaths in the developing world, many of them children. One child dies every eight seconds from a waterborne disease; 15 million children a year."[41]
Vital aquifers everywhere are becoming contaminated with toxins. Once an aquifer is contaminated, it is not likely that it can ever recover. Contaminants are more likely to cause chronic health effects. Water can be contaminated from pathogens such as bacteria, viruses, and parasites. Also, toxic organic chemicals can be a source of water contamination. Inorganic contaminants include toxic metals like arsenic, barium, chromium, lead, mercury, and silver. Nitrates are another source of inorganic contamination. Finally, leaching radioactive elements into the water supply can contaminate it.[42]
Some large or small conflicts of the future may be fought over some aspects of water, including availability, quality, and control. Water has also been used as a tool in conflicts or as a target during conflicts that start for other reasons.[43] Water shortages may well result in water conflicts over this precious resource.[44]
In West Africa today and in many other places, Nepal, Bangladesh, India (such as the Ganges-Brahmaputra), and Peru, major changes in the rivers, generate a significant risk of violent conflict in coming years. Water management and control could well play a part in future resource wars between contending parties desiring scarce resources.[45]
No matter how freshwater is used, whether for agriculture, industry, or municipalities, there is great potential for better conservation and management. Water is used inefficiently nearly everywhere. Until actual scarcity hits, many take access to freshwater for granted. Water resources can be properly managed and water can be conserved. And, sometimes “backstop” water sources are viable.
Water conservation refers to reducing the use of water.[46] There are several things that can be done to conserve water. Most irrigation systems waste water. Typically, only between 35% and 50% of water withdrawn for irrigated agriculture ever reaches the crops. Most soaks into unlined canals, leaks out of pipes, or evaporates before reaching (or after being applied to) the fields. Swales and cisterns can be used to catch excess rainwater and store it for the dry season. Water should be used more efficiently in industry. Industry should use a closed water cycle if possible. Also, industry should prevent polluting water so that it can be returned into the water cycle. Whenever possible gray waste water should be used to irrigate trees or lawns. Water drawn from aquifers should be recharged by treating the wastewater and replacing it back into the aquifer.[47] Finally, water can be conserved by not allowing fresh water to be used to irrigate luxuries such as golf courses. Luxury goods should not be produced in areas where fresh water has been depleted. For example, 1500 liters of water is used on average for the manufacturing of a single computer and monitor.[48]
Sustainable water management involves the scientific planning, developing, distribution and optimum utilizing of water resources under defined water polices and regulations. Examples of policies that improve water management include the use of technology for efficiency monitoring and use of water, innovative water prices and markets, irrigation efficiency techniques, and much more.[49]
Experience shows that higher water prices lead to improvements in the efficiency of use—a classical argument in economics, pricing, and markets. Many examples support this approach. In 2008, Clark County, Nevada, raised its water rates to encourage conservation.[50] Economists propose to encourage conservation by adopting a system of progressive pricing whereby the price per unit of water used would start out very small, and then rise substantially for each additional unit of water used. This approach—tiered rate structures - has been used for many years in many places, and is becoming more widespread.[51] A Freakonomics column in The New York Times similarly suggested that people would respond to higher water prices by using less of it, just as they respond to higher gasoline prices by using less of it.[52] The Christian Science Monitor has also reported on arguments that higher water prices curb waste and consumption.[53]
Conversely, certain kinds of subsidies can lead to inefficient use of water. Water subsidies often involve contentious policy issues that are political in nature. In 2004, the Environmental Working Group criticized the U.S. federal government for selling subsidized water to corporate farms for an average price of only $17 per acre foot (326,000 gallons).[54]
In chapter 10 of his book The Ultimate Resource 2, Julian Simon claimed that there is a strong correlation between government corruption and lack of sufficient supplies of safe, clean water. Simon wrote, "... there is complete agreement among water economists that all it takes to ensure an adequate supply for agriculture as well as for households in rich countries is that there be a rational structure of water law and market pricing. The problem is not too many people but rather defective laws and bureaucratic interventions; freeing up markets in water would eliminate just about all water problems forever... In poor water-short countries the problem with water supply—as with so many other matters—is lack of wealth to create systems to supply water efficiently enough. As these countries become richer, their water problems will become less difficult...".[55] This theoretical argument, however, ignores strong barriers to open water markets, including the difficult of moving water from one region to another, water rights laws that prevent redistribution based solely on economic value, and grossly imperfect information on water use. And indeed, actual experience with peak water limits in some wealthy, but water-short countries and regions still suggests serious difficulties in reducing water challenges.
Extensive research has shown the direct links between water resources, the hydrologic cycle, and climatic change. As climate changes, there will be substantial impacts on water demands, precipitation patterns, storm frequency and intensity, snowfall and snowmelt dynamics, and more. Evidence from the IPCC Working Group II, has shown climate change is already having a direct effect on animals, plants and water resources and systems. Some findings of a 2007 report (Climate Change 2007: Climate Change Impacts, Adaptation and Vulnerability) include : 75–250 million people across Africa could face water shortages by 2020. Crop yields could increase by 20% in East and Southeast Asia, but decrease by up to 30% in Central and South Asia. Agriculture fed by rainfall could drop by 50% in some African countries by 2020.[56] A wide range of other impacts could affect peak water constraints.
Loss of biodiversity can be attributed largely to the appropriation of land for agroforestry and the effects of climate change. The 2008 IUCN Red List warns that long-term droughts and extreme weather puts additional stress on key habitats and, for example, lists 1,226 bird species as threatened with extinction, which is one-in-eight of all bird species.[57][58]
The concept of a "backstop" resource is a resource that is sufficiently abundant and sustainable to replace non-renewable resources. Thus, solar and other renewable energy sources are considered "backstop" energy options for unsustainable fossil fuels. Similarly, Gleick and Palaniappan defined "backstop water sources" to be those resources that can replace unsustainable and non-renewable use of water, albeit typically at a higher cost.[2] The classic backstop water source is desalination of seawater. If the rate of water production is not sufficient in one area, another "backstop" could be increased interbasin transfers, such as pipelines to carry freshwater from where it is abundant to an area where water is needed.[46] Water can be imported into an area using water trucks.[46] The most expensive and last resort measures of getting water to a community such as desalination, water transfers are called “backstop” water sources.[1] Fog catchers are the most extreme of backstop methods.
To produce that fresh water, it can be obtained from ocean water through desalination.[46] A January 17, 2008 article in the Wall Street Journal stated, "World-wide, 13,080 desalination plants produce more than 12 billion US gallons (45,000,000 m3) of water a day, according to the International Desalination Association."[59] Israel is now desalinizing water at a cost of US$0.53 per cubic meter.[60] Singapore is desalinizing water for US$0.49 per cubic meter.[61] After being desalinized at Jubail, Saudi Arabia, water is pumped 200 miles (320 km) inland though a pipeline to the capital city of Riyadh.[62]
However, there are several factors that currently keep desalination from being the cure-all for water shortages: the high capital costs to build the desalination plant, the high cost of the water produced, the energy required to desalinate the water, the environmental issues with the disposal of the resulting brine and the high cost of transporting water.[63]
Nevertheless, some countries such as Spain are increasingly relying on desalination because of the continuing decreasing costs of the technology.[64]
At last resort, it is possible in some particular regions to harvest water from fog using nets. The water from the nets drips into a tube. The tubes from several nets lead to a holding tank. Using this method, small communities on the edge of deserts can get water for drinking, gardening, showering and clothes washing.[65] Critics say that fog catchers work in theory but have not succeeded as well in practice. This is due to the high expense of the nets and pipe, high maintenance and low quality water.[66]
An alternative approach is that of the Seawater Greenhouse which consists in desalinating seawater through evaporation and condensation inside a greenhouse using solar energy as the only energy supply. Succeful pilots have been conducted growing crops in desertic locations and a commercial operation is currently running in Australia[67].