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IAEA General Conference
45th Regular Session



Programme
Biting the fly
Saving a mother's life
Counting every drop
Finding safe waters below

Serving Human Needs

Counting Every Drop

Isotope hydrology permits better management of precious water supplies and provides a view of climate change through a prism to the past
by Peter Rickwood, IAEA Division of Public Information

Its water supply faltering the future of Guelmin, an old desert town in the south of Morocco, looked grim unless a new source was found says Abdelaziz Zerouali.

"Without sufficient water the people of Guelmin would have had to get out of the region," said Zerouali, a hydrologist in Morocco’s water directorate.

But where should a population of 100,000 townspeople, small farmers, and nomads raising camels and sheep, go to and where should they look for water?

Guelmin is on the edge of the Sahara in the south of a country of 27 million people, where water is a scarce commodity.
Monitoring Climate
Unlocking Water's Code

This is Morocco’s doorway onto the desert, where the Chergui wind raises temperatures above 40C in late spring and summer. Without swift resolution before its water ran out, Guelmin would have been caught in a vortex of events spinning out of its control.

The dilemma confronting the old town sums up a parlous global situation that is worsening: "year by year demand was increasing, " said Zerouali. "This was a little aquifer…a few springs with little flow in a valley."

In the 20th century as the human population tripled, fresh water consumption rose six-fold.

Without more efficient water use, by 2025, about half the world’s population will be living in high water stress regions, where agricultural, industrial and domestic users compete, says the World Water Vision Unit of the World Water Council.

As it is, one in five people don’t have access to safe and affordable drinking water - and each year over three million people die of waterborne diseases, among them more than two million young children.

A key goal of the United Nations’ Millennium Report is to reduce by half the number of people without adequate, affordable and safe water.

However, to achieve it will require not only better management of water but knowledge about which available reserves are able to provide long term support.

It’s not as simple as drilling a hole in the ground, or diverting a watercourse. The bid to develop viable new supplies is frequently overshadowed by high cost, frustration and failure.

A groundwater system can be a complex and unknown maze hidden deep beneath the surface of the Earth.

When hydrologists find such a source they need to know whether it will become salty, or if there is a risk from pollution? What is the amount of use it can sustain -- is there a water supply renewing it.?

Or is it palaeowater - a fossil reserve, the legacy of a wet period in Earth’s history, that once used will never be replenished, whose use is as unwise as building a wooden house and burning it to stay warm.

The traditional tools available - long term records that in many developing counties are simply not available - are painstakingly slow, says Pradeep Aggarwal, head of the isotope hydrology section in the United Nations International Atomic Energy Agency (IAEA).

In Guelmin hydrologists knew where to find a new source of water in less than two years.

The dwindling aquifer that supplies the town is now being recharged by diversion of a watercourse, 80 km. away, that previously flowed, untapped, into the sea.

The success in finding a solution to Guelmin’s uncertain future -- Zerouali declares it a victory -- was sealed by isotope hydrology, a technique that is increasingly being applied in management of the global water crisis.

"It gave us another tool," said Zerouali. "The study of water resources is difficult and it is important that we can use many tools as possible for better understanding."

Isotope hydrology is not a silver bullet, but it fine tunes information about the pulse of water on Earth, providing broad application to improved understanding of the complex process by which it is transported.

It is being used to not only penetrate the darkness about managing fresh water reserves, but about climate change -- water vapor is one of the most abundant and important greenhouse gases -- the safety of dams and geothermal energy.

The Pulse of Water

On Earth water moves in a complex dance between the sea, in the air, and land.

This great pulse of water, of transpiration from the leaves of trees, evaporation from ocean and lakes, falling rain, rivers, or groundwater, is known as the hydrological cycle.

At each stage there is a small change registered by a difference in the concentration of oxygen and hydrogen isotopes in water that establishes a fingerprint. Isotopes of pollutants in the environment, such as trace metals, or chemical compounds that are dissolved in water, also provide clues.

Isotopes are atoms of an element that are chemically identical but physically different. Nuclear science is able to distinguish them using mass spectometry, to "weigh" them.

Both hydrogen and oxygen, the elements of water, possess mostly light isotopes.

When there is evaporation of water vapour from the ocean their heavier isotopes condense first and fall as rain before the light water.

Most water vapour in the atmosphere is generated over oceans. The further rain falls from the coast the fewer heavy isotopes it contains.

But when water vapour condenses to form rain, heavier isotope laden water falls first, and the further it falls from the ocean over land the less heavy isotopes it will contain.

Mountains and winds make a slight difference, but the process can be measured and scientifically interpreted. By determining the composition of isotopes in a water sample a record of its passage can be assembled.

This allows hydrologists to navigate groundwater sources and determine their history and the pathways they have followed: whether the reserve is replenished by rain, is at risk from pollution, whether it is young, or old water.

Morocco added isotope hydrology to its tool kit for water management after the IAEA initiated a four year program to provide isotope hydrology to nine North African countries.

Morocco’s centre for nuclear research has now set up its own isotope hydrology laboratory with technical help from the agency. It is the 42nd such laboratory for which the IAEA has provided support in a developing nation, as part of its commitment to building local skills by transferring technology.

Nabil Mosleh of the nuclear centre said that it will support Morocco’s water authority, by applying isotope hydrology, to map the country’s water reserves. The isotopic hydrology laboratories will also act as a quality assurance centre for neighboring African countries.

Population and Climate

Although it is estimated there is sufficient fresh water on Earth to support about 20 billion people, seasonal weather patterns disrupt its supply and distribution is uneven.

China has 21 per cent of the Earth’s population and, in its rivers and lakes, seven per cent of its water. Lake Baikal in south eastern Siberia contains one fifth of the world’s total surface fresh water.

The human population is expected to continue its relentless growth from six billion at the turn of the century to nine billion by 2050.

Hand in hand with the soaring population the world is likely to become warmer as climate change persists. Prudent management of water will become even more crucial and more challenging.

The leading edge of climate change is already being felt with heavier rainfall in a slim band around the tropics and in temperate and higher zones in the northern hemisphere, according to findings of the Intergovernmental Panel on Climate Change (IPCC). In parts of Asia and Africa there are more frequent periods of drought.

What happens next, its magnitude, how human societies can adapt and what effective defenses can be built to withstand the adverse effects of climate change, requires more understanding of the flux of water on Earth.

Climate change – perhaps never so fast before – is not a new phenomenon on the planet.

Clearer knowledge about previous periods of climate change would be a touchstone for climate experts grappling with current events and may make the difference between providing sufficient drinking water, food and energy in future.

The IPCC has set as a priority area the need to reconstruct past climate periods in order to have a key to understanding the present.

Riddles abound in Earth’s climate history. Why in the 10,000 year period since the termination of the last great ice age has there been such rapid see-sawing between periods of warming and cooling?

Assembling climate history from information provided by conventional measuring is limited to time spans of decades or a century.

The sweep of time to draw distinctions between industrial and pre-industrial era climate change, alone, needs a system that clocks centuries.

Isotopes open a window onto extended periods of weather events over thousands of years. Their signatures are preserved wherever the water cycle is recorded, In ocean and lake sediments, tree rings, glaciers and ice caps, deposits in caves, and groundwater.

At a conference organized by the IAEA in Vienna, in April 2001, experts from 38 countries reported on the use of isotopes in a variety of applications.

They ranged from assessing the role of deforestation in the Amazon Basin and its impact on the hydrological cycle, to recording changes in climate regulating ocean currents, in the World Ocean Circulation Experiment.

Monitoring Climate

A little known organization, a product of the Cold War, has been keeping isotopic records of the climate during four decades.

In 1961 an international program was initiated to monitor the movement of fallout of radioactive isotopes from nuclear weapons testing in the atmosphere.

At its height there were over 500 testing stations around the planet in the Global Network for Isotopes in Precipitation (GNIP), collecting rain samples to be measured for isotope content. Declining levels of radioactivity led to the reduction of the network to about 200 meteorological stations.

The information collected by the IAEA and World Metreological Organization (WMO) has renewed significance because it provides a benchmark for global warming. There is pressure to restore the network to its former strength.

From outer space the Earth is a blue orb that appears to be mostly covered in water.

Over 97 per cent of the water on Earth is salt or brackish. Of the remainder about 75 per cent of it is inaccessible, locked away in ice caps and glaciers.

The inventory of fresh water, available for human use, is less than one tenth of one per cent of all of Earth’s water.

The lament of the poet Samuel Taylor Coleridge’s Ancient Mariner, "water, water, everywhere nor any drop to drink," may seem most appropriate.

But the conclusion of the World Water Vision, to whose development 15,000 people contributed, is that the water crisis is a crisis of management.

"We have badly threatened our water resources with bad institutions, bad governance, bad incentives, and bad allocations of resources".

Solutions are available and others are being developed, some supported by tools such as isotope hydrology, that can divert the crisis.

And it will take better understanding of the steps to the ancient dance between water and climate before it’s clear how events occurring now will affect the hydrological cycle and the provision of water.

But there is no other choice.

"Good water, good life,
poor water, poor life,
no water, no life"

--Peter Blake, British artist, b.1932

Unlocking Water's Code

Consider: water the element that drives Earth’s climate and keeps the planet habitable makes up over 60 per cent by weight of our bodies.

Forty years ago the human population was three billion; today it is over six billion. By 2050 it is expected to hit nine billion. But the amount of water available to meet its needs remains unchanged. Without water human beings survive little more than three days.

The case to be made for water – an irreplaceable element for survival on Earth – is, in the parlance of law, open and shut.

The case to be made for raising knowledge by which to better manage its store on Earth is equally compelling. If current rates of use prevail, half the population will be short of water by 2025.

However, locked in every drop of water is information that can be used as a tool in managing it more wisely. Its application offers better understanding of climate change, and helps meet the challenge of providing access to safe drinking water for the one billion people on Earth without it.

A key to unlocking water’s code is isotope hydrology, by which a comprehensive picture can be built up establishing its source, its age, movement, threat from pollution, all of which is critical to making more efficient use of it.


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