New Tools; New Applications; New Challenges
Isotope hydrology has evolved into a multidisciplinary field. As
new approaches are developed, new applications and tools are
added to the isotope toolbox. For example:
Boron isotopes can now be used to identify traces of sewage
pollution in groundwater.
Chlorine isotopes can supply information about the origin of the
salinity and the complexities of flow in large, slow moving
groundwater systems. They can estimate the age of water and may
indicate the size of a reservoir.
Methods are now further refined for the measurement of isotopes
like krypton-85 and helium-3 for determining the age of young
and the origins of fluids.
Traces of now-banned chemical species such as freons can be
employed as environmental tracers of surface pollutants in
shallow ground water.
Among the key challenges in future isotope applications are:
Developing approaches to address the water problems of megacities
Responding to the complex and deepening crisis of environmental
Contributing to understanding global climatic change
Advancing professional sophistication in the practical
of isotope techniques
Raising awareness of the role of isotope techniques in water
resources management and geothermal energy resources.
Isotopes Reveal Leaks in a Dam
The El Colorado dam in Chile forms a reservoir with a volume of
about 1.5 cubic kilometres. Major leakages beneath the wall
developed and a grid of wells was drilled downstream from the dam
to relieve the groundwater pressure.
A field survey revealed that reservoir water had a mean deuterium
concentrarion of -950/00, which differs
from local groundwater having a mean 2H =
-70/00. Analysis of water samples from the
boreholes showed that leakages were most pronounced near the
flanks of the dam wall. Guided by this information, an area of
major leakage on the reservoir floor was later confirmed, using
the artificial radioactive tracer 131I. Mitigation
measures to prevent the eventual collapse of the dam were then
undertaken at this location.