Environmental Tracers to Study the Origin and Timescales of Spring Waters

Environmental tracers can add valuable insights to the assessment of spring vulnerability that are not available with any other method. They can identify the origin of contaminants, help to specify from which aquifer formation(s) the water originates, give clues on the infiltration conditions of the water such as temperature and altitude to identify recharge locations and processes, and define the timescales of groundwater flow and, in ideal cases, deconvolute the age distribution. Environmental tracers will rarely directly define the vulnerability of springs toward changes in hydraulic gradient, but they may give invaluable contributions to a conceptualization that is the basis for assessing the impact of a change in hydraulic gradients. The available tracer tools are discussed in this chapter and brought into the context of other investigations such as conceptual hydrogeological models, geophysics, and hydrochemistry. A detailed case study demonstrates the capabilities under ideal conditions.