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IAEA Marks World Water Day

Laser Spectrograph Device Revolutionizes Water Resource Management

Emilio Hespanhol, a chemist from Universidade Estadual Paulista in São Paulo, Brazil, uses a laser spectrograph during training in the IAEA's Isotope Hydrology Laboratory. The laser spectrograph consists of both the large black body that houses the laser, and on which the monitor rests, and the sampling apparatus on the left. (Photo: S. Henriques/IAEA)

Finding available, clean and safe water is a cornerstone of human development. Nuclear techniques can help in identifying and guarding water resources in countries all over the world.

Sierra Leone receives most of its rainfall between July and September but for six months of the year (November to April), rainfall is virtually non-existent. During the rainy months farmers and households practice rainwater harvesting. And when the rains cease, they use water stored deep beneath the surface - called groundwater.

Researcher Mohamed Matthew Blango from Njala University worries about the negative impact rainwater harvesting could have on the dynamics and recharge rates of groundwater. He and his team at the university are part of an IAEA-funded project studying groundwater hydrology in Sierra Leone.

Last week he came to the IAEA's headquarters in Vienna, Austria to be trained in the use of a new machine that promises to radically improve their ability to test their theories and understand the country's freshwater resources. "Water is a key bottleneck for the economic development of our country. We need to find a reliable supply of fresh water for the dry season," said Blango.

Detecting the age and history of water

The relatively small laser spectrograph "uses finely tuned laser light to excite and detect specific isotopic molecules in water, enabling us to answer questions like: Is this lake evaporating? Will this region have enough water to meet the needs of the growing population? Is our dam leaking? How can we share the water resources of our transboundary aquifer equally?" said Leonard Wassenaar, who heads the IAEA’s isotope hydrology lab. See also this video explaining the use of isotope techniques. 

The laser spectrograph is used in water resource management, which involves figuring out how much fresh water a country has, where that water is coming from, where it's going and what is happening to it along the way. Isotopes of water, depending on their origin, age, and the processes they’ve been through, have unique markers or fingerprints. These fingerprints are what the laser spectrograph measures to provide invaluable information to water resource managers, governments and scientists.

"The IAEA's water resources programme is an important part of the global effort to address water shortage and quality, over-exploitation, and the impact of climate change on water resources," says Luis Araguás Araguás, an isotope hydrologist at the IAEA.

"We receive a lot of rainfall but much of it is wasted as runoff," said Blango from Sierra Leone. "So I want to see how we can impact the recharge of groundwater. That will in turn help in irrigation during the dry season."

Sierra Leone has already received a laser spectrograph from the IAEA, and Blango’s training also includes device assembly and maintenance.

To date, the IAEA has purchased laser spectrographs for use in more than 50 Member States, and has provided cost-free training in how to use the equipment to 100 scientists from 58 countries.

Hands-on

During the week of 16 to 20 March six scientists from Brazil, Cameroon, Greece, Italy, Sierra Leone and South Korea attended a training course at the IAEA to learn how to use the device and interpret its results. Lectures take up the first two days. And by the third, students were working on their own projects.

One of the six is Emilio Hespanhol, a chemist from Brazil. He's part of a team at Universidade Estadual Paulista in São Paulo that's working to create a comprehensive database of isotopic measurements in water from across the country in order to "facilitate future studies".

The creation of this database is the first step in the government's efforts to improve water resource management across the South American nation. The Guarani Aquifer, one of the largest groundwater reservoirs in the world, has been one of the resources Brazil and its neighbouring countries have been studying using nuclear techniques.

Revolutionary tech

Wassenaar describes the laser spectrograph as nothing short of revolutionary. Its low cost, low energy needs and sturdy build mean that many more developing countries can reap the benefits of isotopic analysis for water management. And it can be operated after just one week of training, in contrast with a mass spectrometer that requires an operator with an advanced degree and years of experience.

"In countries where the power supply is unreliable, and electricity gets cut off at night, the fact that the laser spectrograph can simply be turned back on with no ill effects and virtually no waiting time is very useful," said Wassenaar. "I've seen people run laser instruments in the field from the back of a truck."

The problem with old water

The isotopic fingerprinting undertaken with this equipment is helping countries answer some tough questions about freshwater availability in the next half century and beyond. Especially in places where there are acute water shortages.

"The planet has a dramatically increasing population and in many parts of the world that puts huge stress on water resources," said Wassenaar.

"If you're pumping ancient water that has been stored in the earth for tens of thousands or millions of years, it will not replenish very quickly. That could be a potential threat to your water resource. If isotopic analysis tells you that your water is very young, you will have a fast replenishment rate. Then that resource is a little bit easier to manage."

As a necessity for life, water is without a substitute. The IAEA supports many Member States through technical cooperation and other projects worldwide, helping them use nuclear techniques to measure and manage their water resources - from establishing an isotope laboratory in Iraq for studying groundwater, to using drip irrigation in Mauritius for improving crop yields and conservation, to developing water use and management policies in the Sahel region of Africa. 

We receive a lot of rainfall but much of it is wasted as runoff. So I want to see how we can impact the recharge of groundwater. That will in turn help in irrigation during the dry season.
Mohamed Matthew Blango, Researcher, Njala University, Sierra Leone