Feature Stories

World Water Day 2005:  Water for Life

With assistance from the International Atomic Energy Agency, Morocco is using isotope hydrology to find new sources of water. (Photo credit: L. Wedekind/IAEA).

New Sources of Water in Morocco

IAEA Helps North African Countries

(From World Water Day 2002)

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? Droughts, attributed to global climate change, are becoming more common in Morocco. In the 20th century, four of its 11 droughts were in the decade that ended in the mid 1990s.

Guelmin is on the edge of the Sahara in the south of a country of 27 million people, where water, a scarce commodity, is becoming scarcer. 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 in serious trouble.

The dilemma confronting the old town of Guelmin 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 called for in 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 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, which 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 programme to transfer this technology 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.