» Hydrological tracing

Hydrological tracing


Artificial tracers in hydrology

The use of artificial tracers in hydrogeology is a very ancient technique. It is an effective tool for managing and preserving water resources and protecting the environment.


The increasing demand for hydrological assessments requiring the use of artificial tracers is motivated by two main factors: the challenge of managing water resources and the growth in pollutant shipments.


This new technique means that the fluorescent and saline properties of tracers can be employed to detect the point of origin of water, the location of run-off and hydraulic connections, and to reveal the risks of pollutants spreading.


The results obtained can provide definitive answers to all these problems, helping empower economic and social actors regarding their environmental impact.


Below, a reminder of the different possible applications and their objectives:





Abstraction of groundwater/spring water

Delimitation of a supply catch basin

Check that a determined point is found in the catch basin

Study of the respective inputs of different waters

Protection areas of under-ground waters

Check of an hydraulic connection between the injection and catch point

Study of transit times and flow velocity

Sizing of protection zones

Supply areas of run-offs

Delimitation of feeding areas

Check that a given location is found in the feeding area of capture

Knowledge of underground inflows

Risks assessment / Incidents simulation

Check of a hydraulic connection and an installation/ a capture site

Assessment of the operational timing

Monitoring of implantation of the supervision point

Estimate of the size of the impacts during risk assessments  

Simulation of the incidental effect causing infiltration of dangerous liquids in underground waters

Contaminated Sites / Dubious areas

Study of seepage runoff

Verification of the right place of sampling points downstream from a site


Verification of outflows under existing landfills 

Monitoring of seepage paths : meteoric waters flow towards foreseen drainages

Monitoring of waterproofing of cover layers

Assessment of sites for new landfills : e.g. verification that a site is away from a supply catch basin  

Verification of the right spot of the surveillance point

Interaction surface waters / ground waters

Detection and localization of seepage or water flows exfiltration sections

Detection of outflows under water streams

Identification of drain places of closed lakes

Detection of parasite waters

Identification et quantification of the arrival to a seepage catch coming from a water stream

Verification of the arrival to a capture of close rainwater infiltrations


Control of the representativeness of underground water samples through tagging the drilling fluid

Control of leak-proof caps dividing various levels of catchment

Expert assessment in case of damages

Verification of the point of entry of waters seeping into a building 

Determination of aquifer parameters / Modelling of ground-water flows

Determination hydraulic parameters such as  the  outflow velocity and dispersion coefficient  

Calculation of the storing volume from empty volumes allowing outflow

Adapt and validate outflow models and mass transport in solution form

Verifications of outflows directions predicted with respect to observed directions


In particular in karstic environment, artificial tracing remains essential to mark out hydrogeological systems and assess the transit characteristics from the Residence Time Distribution (RTD). Although karstic and cracked environments concentrate the larger variety of tracing applications, the latter are not limited to this type of environment:


Aquifers Types

Ways for tracers’ application

Karstic Aquifers

Regional recognition of underground outflows

Development of conceptual models of karstic systems

Delimitation of catchment basins from karstic sources

Highlight of the flux of karstic waters

Aquifers in loose rocks

Regional studies of underground outflows

Delimitation of catchment basins

Experimental simulation of the spread of pollutants

Determination of aquifer’s parameters

Delimitation of input areas of polluting material

Flows in aquifer slopes and in cracked rocks

Highlight of outflows in bedrocks

Studies of aquifer structures (cracks, rifts, furrow etc.)


Highlight of preferential flows in water slopes (water veins…)



Artificial tracers and Hydrology



CATALOG 2022/2023







The use of fluorescent dyes as tracers in highly saline groundwater


Source: Journal of Hydrology ( 2008) 358, 124-133



Utilisation des traceurs artificiels en hydrogéologie

Guide pratique


Groupe de travil Traçage de la Société suisse d'hydrogéologie SSH


Source: Berichte des BWG, Série Geologie - Rapports de l'OFEG, Série Géologie - Rapporti dell' UFAEG, Série Géologia No 3 - Berne 2002



Toxicité et écotoxicité des principaux tracurs fluorescents employés en hydrogéologie et de leurs produits de dégradation




Source: KARSTOLOGIA n°58, 2011 (41 à 53)



Evaluation de traceurs artificiels pour l'étude du transport de solutés dans les eaux souterraines




Source: Rapport du BRGM R 38323 de Février 1995



Guide méthodologique
Les outils de l'hydrogéologie karstique pour la caractérisation de la structure et du fonctionnement des systèmes karstiques et lévaluation de leur ressource

Mars 2010


Proposition dune grille dévaluation des résultats des traçages en milieu karstique (au moyen de traceurs fluorescents)

CFH - Colloque Hydrogéologie et karst au travers des travaux de Michel Lepiller 17 mai 2008


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