In developed and developing countries alike, fierce competition among water users is rising as people demand more and more from limited water resources. Tensions are particularly severe in places that face population pressures, rapid urbanization, and urgent development needs.
A number of developed, water-short countries—including Belgium, the United Kingdom, Poland, and Singapore—have faced tensions over water. The western United States has witnessed tension between (a) farmers with irrigation needs, and (b) urban areas with municipal demands. San Diego, California is a classic case, but the city negotiated a landmark deal with vegetable growers in the Imperial Valley. The farmers now conserve water and sell the surplus to the city (Purdum, 1997).
China is already practising what many water experts call the “zero-sum game” of water management. The zero sum game—when authorities increase water supply to one user by taking it away from another—involves both competing areas and competing types of use, as when cities compete with farmers or when human needs compete with those of ecosystems. China's freshwater supplies have been estimated to be capable of supporting 650 million people sustainably—only half of the country's current population of 1.2 billion (Qu Geping, personal communication, 1993). Across northern and central China some 300 major cities, including Beijing, face critical shortages. There is simply not enough water to meet the competing needs of the country's cities, industries, and agriculture. China has depleted underground aquifers and dammed, diverted, and drained surface waters. The water table under China's capital has dropped by roughly two meters a year for the last decade. One-third of the wells dried up because the pipes no longer reach the shrinking aquifer (Brown & Halweil, 1998). As the influx of China's rural farm workers seeking urban jobs grows ever larger, Beijing's water shortages are expected to worsen. The government is planning a huge aqueduct that will ferry water from the Danjiangkou Reservoir in Henan Province to Beijing, across 1,300 kilometers of heavily farmed agricultural land—land that also needs the water for food production.
China's Yellow River is a classic case of the zero-sum game in operation. The river is so over-subscribed that, for an average of 70 days a year for the past decade, its waters have dried up before reaching the Bohai Sea. In 1995, this dry period lasted for 122 days. In May 1996, one of the few years when farming villages near the river's mouth could take water to feed their crops, the government told them not to touch a drop. Instead, all of the water went to a state-owned oil field further downstream, bypassing hundreds of parched farms and factories along a 400- kilometer stretch of the river (Tyler, 1996).
Monday, October 8, 2007
Water problems within countries.
Regions and states of many large countries (such as India, China, and the United States) could also join the water-stressed category. Already, 19 major Indian cities face chronic water shortages, and India as a whole is expected to enter the water-stressed category by 2030 (Gardner-Outlaw & Engelman, 1997).
China, which has 22 percent of the world's population but only seven percent of all freshwater runoff, will be just above the 1,700 cubic meters per capita line that designates “waterstress.”
China, which has 22 percent of the world's population but only seven percent of all freshwater runoff, will be just above the 1,700 cubic meters per capita line that designates “waterstress.”
The Era of Water Shortages
Hydrologists consider a country to be under water stress when its annual water supplies drop to between 1,000 and 1,700 cubic meters per person. In turn, countries face water scarcity when their annual water supplies drop below 1,000 cubic meters per person. Once a country enters the water-scarce category, it faces severe constraints on food production, economic development, and protection of natural ecosystems.
More and more countries are facing water stress and scarcity as their populations grow, urbanization accelerates, and water consumption increases. Thirty-one countries (with a combined population of close to half a billion) faced water stress or scarcity as of 1995. The number of people estimated to live in water-short countries increased by nearly 125 million between 1990 and 1995.
By 2025, 50 countries and more than 3.3 billion people will face water stress or scarcity. By 2050, the number of countries afflicted with water stress or scarcity will rise to 54, and their populations to 4 billion people—40 percent of the projected global population of 9.4 billion. The majority of these countries—40 of them—are in the Near East, North Africa, and sub-Saharan Africa (Gardner-Outlaw & Engelman, 1997; UNFPA, 1997).
More and more countries are facing water stress and scarcity as their populations grow, urbanization accelerates, and water consumption increases. Thirty-one countries (with a combined population of close to half a billion) faced water stress or scarcity as of 1995. The number of people estimated to live in water-short countries increased by nearly 125 million between 1990 and 1995.
By 2025, 50 countries and more than 3.3 billion people will face water stress or scarcity. By 2050, the number of countries afflicted with water stress or scarcity will rise to 54, and their populations to 4 billion people—40 percent of the projected global population of 9.4 billion. The majority of these countries—40 of them—are in the Near East, North Africa, and sub-Saharan Africa (Gardner-Outlaw & Engelman, 1997; UNFPA, 1997).
A Future of Scarcity
Years of rapid population growth and increasing per capita consumption have squeezed the world’s freshwater resources. As global population has grown to nearly 6.1 billion today (and continues to grow by about 78 million people each year), the demand for fresh water in some areas exceeds nature's capacity to provide it. A growing number of countries are expected to face water shortages in the near future—shortages that will be fueled by problems both on the demand side (notably rapid population growth) and on the supply side (mainly inadequate water supplies and poor policies).
Declining Water Availability Per Capita
There is no more water on earth now than there was 2,000 years ago, when the population was less than 3 percent of its current size. Fresh water's per capita availability, which has been falling for centuries, has been dropping more precipitously in recent years as the globe's population growth has exploded. Unsurprisingly, the availability of fresh water has also fallen, from 17,000 cubic meters per person in 1950 to 7,044 cubic meters in 2000 (World Resources, 2000). The supply of fresh water per capita is one third lower now than it was as recently as 1970, a direct result of the nearly 2 billion people added to the planet since.
While population growth rates are slowing in most developing countries, absolute numbers of people added each year remain near historic highs. As a result of projected population growth, global per capita availability of fresh water is likely to be no more than 5,100 cubic meters in the year 2025 (Gardner-Outlaw & Engelman, 1997).
China and India, the world's first and second most populous countries, respectively, provide examples of how even modest population growth rates can translate into large absolute numbers because of an already-enormous population base. China's population growth rate in 2000 was only 0.9 percent—but, with China's total population at over 1.2 billion, even this small growth rate translates into an additional 12 million people each year. Similarly, India's population growth rate of about 1.8 percent means that about 18 million people a year will be added to its current population of one billion. The world's annual population growth of 78 million a year (as of 2000) implies an increased demand for fresh water on the order of 64 billion cubic meters a year—an amount equivalent to the entire annual flow rate of the Rhine River, assuming countries continue to withdraw water at current rates (Clarke, 1991). And, as noted above, rapid population growth not only makes it increasingly difficult to provide adequate supplies of fresh water; it can also strain resources for proper sanitation, housing, health care, education, employment, and food supplies.
Declining Water Availability Per Capita
There is no more water on earth now than there was 2,000 years ago, when the population was less than 3 percent of its current size. Fresh water's per capita availability, which has been falling for centuries, has been dropping more precipitously in recent years as the globe's population growth has exploded. Unsurprisingly, the availability of fresh water has also fallen, from 17,000 cubic meters per person in 1950 to 7,044 cubic meters in 2000 (World Resources, 2000). The supply of fresh water per capita is one third lower now than it was as recently as 1970, a direct result of the nearly 2 billion people added to the planet since.
While population growth rates are slowing in most developing countries, absolute numbers of people added each year remain near historic highs. As a result of projected population growth, global per capita availability of fresh water is likely to be no more than 5,100 cubic meters in the year 2025 (Gardner-Outlaw & Engelman, 1997).
China and India, the world's first and second most populous countries, respectively, provide examples of how even modest population growth rates can translate into large absolute numbers because of an already-enormous population base. China's population growth rate in 2000 was only 0.9 percent—but, with China's total population at over 1.2 billion, even this small growth rate translates into an additional 12 million people each year. Similarly, India's population growth rate of about 1.8 percent means that about 18 million people a year will be added to its current population of one billion. The world's annual population growth of 78 million a year (as of 2000) implies an increased demand for fresh water on the order of 64 billion cubic meters a year—an amount equivalent to the entire annual flow rate of the Rhine River, assuming countries continue to withdraw water at current rates (Clarke, 1991). And, as noted above, rapid population growth not only makes it increasingly difficult to provide adequate supplies of fresh water; it can also strain resources for proper sanitation, housing, health care, education, employment, and food supplies.
Freshwater Availability and Us
While 70 percent of the earth’s surface is water, only three percent of it is fresh water—and almost all of that three percent is inaccessible for human use (Lean & Hinrichsen, 1994; Lefort, 1996). About three-quarters of all fresh water on earth is locked away in the form of ice caps and glaciers located in polar areas far from most human habitation. In all, only about 0.01 percent of the world’s total water supply is considered available for human use on a regular basis. If the world’s freshwater supply amounted to the contents of a bathtub, the amount easily accessible to humanity would fill a thimble.
Nevertheless, even this thimble full of water is, in theory, enough to sustain an estimated 20 billion people. But in reality, only a small amount of the freshwater supply is reliable enough to be considered accessible year after year. Globally, 505,000 cubic kilometers of renewable fresh water shifts from the sea to the land every year as rain or snow via the hydrological cycle; but only 47,000 cubic kilometers per year can be considered accessible for human use (Gleick, 2000).
Nevertheless, even this thimble full of water is, in theory, enough to sustain an estimated 20 billion people. But in reality, only a small amount of the freshwater supply is reliable enough to be considered accessible year after year. Globally, 505,000 cubic kilometers of renewable fresh water shifts from the sea to the land every year as rain or snow via the hydrological cycle; but only 47,000 cubic kilometers per year can be considered accessible for human use (Gleick, 2000).
Sunday, September 30, 2007
Population and Fresh Water
Population and water resources are closely connected. The availability of fresh water limits how many people an area can support, while population growth, urbanization, and migration all affect the availability and quality of water resources. Population growth increases demand for water for food production, household consumption, and industrial uses. At some point, however, this increased demand becomes overuse, leading to depletion and pollution of surface and groundwater supplies that can cause chronic water shortages.
Scarce and degraded water supplies also often cause critical health problems. Polluted water, water shortages, and unsanitary living conditions kill over 12 million people a year (WHO, 1997) and cause a great deal of illness such as cholera, hepatitis A, amoebic dysentery, schistosomiasis, and dengue and malaria fevers. And this increasing competition for limited water supplies also causes social and political tensions. River basins and other water bodies do not respect national borders: one country’s use of upstream water often removes that water from use by downstream countries. There remains a real risk across the globe of escalating tension and perhaps conflict over access to freshwater supplies. Slowing population growth, conserving water. In less than 30 years, 50 countries could face serious water shortages, affecting more than 3.3 billion people—40 percent of the projected global population (Gardner-Outlaw & Engleman, 1997). The world, especially water-scarce countries (those with less than 1,000 cubic meters per person per year) that are afflicted with rapid population growth, must slow the growth in demand for water by slowing population growth as soon as possible. Family-planning services will empower millions of couples to space and limit their births if they so desire.
At the same time, the world’s “water profligacy” must end as soon as possible.
Throughout the world, enormous amounts of water are wasted due to inappropriate agricultural subsidies, inefficient irrigation systems, imprudent pricing of municipal water, poor watershed management, pollution, and other practices. The world can no longer afford to waste its precious supplies of fresh water.
Scarce and degraded water supplies also often cause critical health problems. Polluted water, water shortages, and unsanitary living conditions kill over 12 million people a year (WHO, 1997) and cause a great deal of illness such as cholera, hepatitis A, amoebic dysentery, schistosomiasis, and dengue and malaria fevers. And this increasing competition for limited water supplies also causes social and political tensions. River basins and other water bodies do not respect national borders: one country’s use of upstream water often removes that water from use by downstream countries. There remains a real risk across the globe of escalating tension and perhaps conflict over access to freshwater supplies. Slowing population growth, conserving water. In less than 30 years, 50 countries could face serious water shortages, affecting more than 3.3 billion people—40 percent of the projected global population (Gardner-Outlaw & Engleman, 1997). The world, especially water-scarce countries (those with less than 1,000 cubic meters per person per year) that are afflicted with rapid population growth, must slow the growth in demand for water by slowing population growth as soon as possible. Family-planning services will empower millions of couples to space and limit their births if they so desire.
At the same time, the world’s “water profligacy” must end as soon as possible.
Throughout the world, enormous amounts of water are wasted due to inappropriate agricultural subsidies, inefficient irrigation systems, imprudent pricing of municipal water, poor watershed management, pollution, and other practices. The world can no longer afford to waste its precious supplies of fresh water.
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