Contents
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Foreword
Introduction
Managing Water Resources
 Guarding the Guarani
 Poisoned Waters
 Great Lakes
Food Security for the Poor
Health Problems of the Poor
Environmental Management
Strengthening Nuclear Safety
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Guarding the Guarani: Improving Management of South America’s Precious Groundwater

The Guarani is the largest aquifer in South America: it extends over 1.2 million square kilometres in Brazil alone—equal to the areas of England, France, and Spain combined. The system is shared by Argentina, Brazil, Paraguay, and Uruguay, and already supplies some 15 million people in the region. Best estimates show that the Guarani contains enough water to supply 360 million people on a sustainable basis. Already, some 500 cities and towns across Brazil draw their water from the Guarani.

South America, guarani

Isotopic tools are helping four South American countries get a handle on sustainable management of the giant Guarani aquifer. The Guarani watershed is depicted above.

Since water consumption is rising rapidly for domestic, industrial and agricultural uses, the continent is turning increasingly to groundwater, which is especially valuable because it does not normally require chemical treatment. But the Guarani is a unique resource that must be managed strategically and protected to ensure its sustainability.

“The Guarani system is a striking example of an international water body threatened by environmental degradation,” says Karin Kemper, a water resources specialist with the World Bank. “Without better management, the aquifer is likely to suffer from pollution and rapid depletion. Uncontrolled exploitation could reduce it from a strategic water reserve to a degraded resource that is a focus of conflict in the region.”

This is the principal challenge being undertaken by the four national governments together with the Global Environment Facility (GEF), a funding consortium jointly managed by the UNDP, UNEP, and the World Bank. A GEF grant of US$ 27 million is helping to ensure that, in the face of increasing scarcity and pollution of surface waters, the aquifer is preserved and kept available as an important reserve for the future.

The GEF project is supporting the creation of a common institutional and technical framework for managing the Guarani. This entails consolidation of scientific knowledge, implementation of a management plan, and enhancing stakeholder participation through communication and environmental education.

guarani

Isotopic tools are helping four South American countries get a handle on sustainable management of the giant Guarani aquifer.
The Guarani watershed is depicted above.

The governments and the GEF have sought help from the IAEA in utilising the analytical techniques of isotope hydrology. These methods facilitate the systematic measurement and interpretation of hydrological information that cannot be obtained by any other means. Isotope hydrology offers a set of unique tools, which are often the most cost-efficient and easiest to use. Isotopic information is usually combined with other hydrological information to produce a comprehensive understanding of an underground system and provide a scientifically sound basis for management decisions (see box for details).

The principal threat to the aquifer system stems from uncontrolled pollution in its extraction and recharge areas. IAEA participation is improving the understanding of these potential threats.

As Laurence Gourcy of the IAEA Isotope Hydrology Section explains, “This is a unique opportunity to contribute significantly to protecting the Guarani Aquifer by ensuring the quality of the analyses, and the reliability of laboratories and isotope expertise. There is a pressing need for better international collaboration of activities related to isotope hydrology.”

The Power of Isotopic Tools

One body of water appears much like another. But at the atomic level, water can be identified by its natural isotopic composition, which varies according to the history of its pathway through the hydrological cycle. During evaporation and condensation, the concentration of oxygen and hydrogen isotopes making up the water molecule undergoes small changes.

Over 99 per cent of all oxygen is oxygen-16, but the remainder are the heavier isotopes oxygen-17 and oxygen-18. The heavier isotopes evaporate more slowly and condense more quickly. Continuous monitoring of the isotopic content of rain and snow provides scientists with isotopic “fingerprints” for hydrological purposes.

Isotopic analytical methods have many applications in water management including:

• Estimating the extension and limits of an underground reservoir in an aquifer system.

• Determining how quickly the resource is replenished and, therefore the rate at which it can be used.

• Providing estimates of the degree of mixing and interconnection of groundwater in complex aquifer systems, hence providing information on how to manage groundwater extraction from the system.

• Determining the location and proportion of rainfall that is recharging the groundwater systems and providing information on the scale of the recharge, flow, and discharge of groundwater systems, and hence identifying appropriate management strategies.

• Assessing the vulnerability of groundwater to pollution by determining how rapidly it moves (flow rate) and where in the system it is being recharged. Surface sources of pollution can then be identified as natural, industrial, agricultural, or domestic.

Without preventative measures, uncontrolled pollution in its extraction and recharge areas could threaten the Guarani aquifer, which contains sufficient water to supply 360 million people on a sustainable basis.

The IAEA project component is enhancing knowledge in several scientific areas: • Defining the key hydrodynamic features of the aquifer;

• Assessing water quality and differentiation of contamination patterns in terms of origin, impacts, and pathways of pollutants;

• Improving analysis of groundwater's origin and age, evolution, boundary conditions, recharge-discharge charateristics, and geothermal character; and

• Assembling a comprehensive, multilateral database to be shared among the four countries.

The IAEA will also support specialized training and participation of international experts to strengthen applications across the region. “Scientists in the field are currently completing a wells inventory, setting up a monitoring network, determining key parameters to be measured, providing technical training of staff, and preparing a hydrogeological map and conceptual model,” says the IAEA’s Laurence Gourcy. “Within a few years, we hope to have a comprehensive information system functioning fully to guard the Guarani from the most dangerous sources of contamination.”

By building the capacity of local institutions in handling more sophisticated science and technological tools, the IAEA is thus helping South America realize the objective of comprehensive and sustainable management of its precious water reserves.

  Managing Water Resources in an Era of Scarcity
Introduction...

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“Without better management, the Guarani aquifer is likely to suffer from pollution and rapid depletion. Uncontrolled exploitation could reduce it from a strategic water reserve to a degraded resource.”
Karin Kemper,
World Bank
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