Field Tracer Tests Research Articles

An approach to runoff modelling in small karst watersheds using the SWAT model

The soil and water assessment tool (SWAT) is one of the most widely used hydrological models. However, it has not been extensively applied in karst watersheds due to their geomorphological heterogeneity. Karst watersheds contribute up to 50% of water supply in Europe, while in South China alone, over 100 million people subsist on it. Hence, improving model performance for karst areas is an important area of research. Here, we propose a methodology based on field investigation and tracer test aimed at improving the conceptual understanding of the hydrological processes to guide the modeller. The Miaogou watershed was used as a case study to run the SWAT model using daily streamflow data from 2013 to 2016. Model calibration and validation results were found to be positive. Average R2 and Nash–Sutcliffe efficiency index (NSE) solutions for the validation period are 0.70 and 0.65 respectively. CN2 was the most sensitive parameter due to the concave shape of the basin as well as the presence of a sinkhole that conveys recharge faster to the main stream outlet via a spring. Our findings show that a field-based approach to modelling karst areas helps define watershed surface and groundwater boundaries, which is often neglected. It also serves as a secondary validation that can be applied anywhere rather than relying on computer code alone. In addition, tracer tests highlight the subterranean hydrological processes which define hydrological gains and losses necessary for model parameterization. Overall, this study establishes a positive outlook towards extensive application in other karstified regions of the world.

Modeling the Effect of Hyporheic Mixing on Stream Solute Transport

AbstractMixing in the hyporheic zone plays a key role in controlling the fate and transport of contaminants in streams and rivers. Consistently with recent experimental and numerical results, a physically based one‐dimensional solute transport model is presented that represents hyporheic mixing as a diffusion process exponentially attenuated with depth. When vertical diffusion in the sediment bed is not limited by an impermeable boundary, the moments of the breakthrough curves (BTCs) generated by the model exhibit persistent non‐Fickian behavior and are shown to scale consistently with existing experimental evidence. The ability of the exponentially attenuated mixing model to represent experimental BTCs was tested using data from field and flume tracer experiments, and its performance was compared with that of a classic two‐storage zone model. While both models provided an equally good approximation for the BTCs observed in field tracer tests, the exponentially attenuated mixing model provided better fits for the flume experiments. Analysis of the model equations and their solutions shows that, if the flow cross‐sectional area and wetted perimeter are not predetermined, there are infinite sets of parameter values that produce the same space‐time concentration distributions. The result implies that the physical parameters of hyporheic exchange cannot be determined by sole measurements of the solute BTCs in the surface water unless flow cross‐sectional area and average flow depth can be independently estimated.

Solubility of TINOPAL CBS-X fluorescent dye at different EDTA concentrations and pH values: Implications regarding its applicability in field tracer tests

TINOPAL CBS-X has been described in published literature as a fluorescent dye that is suitable for use as a tracer in groundwater investigations. However, several of these field tests have yielded unexpected results. In this study the influence that the complexation agent EDTA (ethylenediaminetetraacetate) and pH have on the solubility of TINOPAL CBS-X have been systematically investigated in the laboratory and the results obtained validated with thermodynamic calculations using the PhreeqC software. Modeling indicated that the amount of EDTA required for complete TINOPAL CBS-X dissolution is, in many aquifers, so great that its use is no longer feasible. However, softening the water by adding NaOH appears to be a promising way to increase TINOPAL CBS-X solubility. Water with a low availability of bivalent and/or trivalent ions yielded solubilities up to two orders of magnitude higher than waters from limestone aquifers with a high Ca2+ ion content. Results revealed that the spectrum of TINOPAL CBS-X applicability as a conservative tracer in aquatic environments is limited to a limited range of specific water chemistries. The long tailing in the breakthrough curve and the retarded breakthrough of TINOPAL CBS-X in a previously reported carbonate karst aquifer field tracer test was accurately reproduced by a transport model with a modified input function based on solubility modeling. Travel times and attenuation by incompletely dissolved tracers are tend to be overestimated, which can be problematic with regard to predictions of contaminant transport, or the delineation of water protection zones. The use of TINOPAL CBS-X as a conservative tracer and the concentrations required needs therefore to be carefully evaluated with respect to water-hardness, pH, alkalinity, and dilution rates. An input script for PhreeqC is provided to help estimate appropriate concentrations of TINOPAL CBS-X, thus enhancing its potential and reliability for future groundwater research.

Tracer test analysis using flow and transport simulation code and new analytical transport model 27 April 2019.

A convergent flow field tracer test, in two phases, with injection of sodium chloride solution, was conducted on a pumping well and neighboring piezometers belonging to the Kovin-Dubovac area drainage system, on the Serbian sector of the Danube River. The initial goal was to determine the values of hydrogeological parameters in order to analyze the results of the subsequent experiments involving injection of the selected solutes. SEAWAT code (through the Visual Modflow™ 2011 interface), as well as the newly developed analytical model for multilayer setting (1D transport solution for tracer injected as a Dirac impulse in a radial convergent flow field), was used to develop and calibrate a model of the studied portion of the aquifer. The new analytical model demonstrated a very good match to the measured values and to the results of numerical simulation, which indicates that it can be of great utility in characterizing transport conditions. PRACTITIONER POINTS: Results confirm the conclusions of research papers on tracer tests that 10-m scale tests regularly point to heterogeneous aquifer. New analytical 1D radial transport model for multilayer setting demonstrated a very good match with numerical simulation and experimental data. Developed analytical model is usable for characterizing transport conditions in a radial convergent multilayer flow field or other settings.

Assessment of Lagrangian particle dispersion model “LAPMOD” through short range field tracer test in complex terrain

In this paper the mesoscale application of the 3D Lagrangian particle dispersion model LAPMOD has been assessed for a field tracer test performed in a short-range complex terrain. The meteorological input was provided through the diagnostic model CALMET, the meteorological pre-processor of the CALPUFF model. The CALMET/LAPMOD coupled system was used to simulate the hourly averaged ground level concentration at 47 discrete receptors. The LAPMOD model has a general tendency to slightly underestimate the hourly averaged ground-level concentrations. A Q-Q plot shows that the predicted concentration distribution has a good comparison with observed one. The Robust Highest Concentration (RHC) indicates that the LAPMOD model slightly underestimates the simulated peak concentration in short-term release conditions. The Fractional Bias (FB), Normalized Mean Squared Error (NMSE), Factor of Two (FAC2), Factor of Four (FAC4) and Factor of Exceedance (FOEX) statistical indices were calculated. The predicted results by LAPMOD are generally in good agreement with observed ones and the model is justified for the use in complex terrain for short-term near-field applications.

Assessment of AERMOD modeling system for application in complex terrain in Pakistan

Atmospheric dispersion models based on Gaussian plume formulation are widely used for regulatory purposes in flat terrain. In this paper, the application of an advanced Gaussian plume modeling system, AERMOD, has been investigated over complex terrain setting through a field tracer test conducted in April 2018 near Islamabad, Pakistan. The model was validated through short term (2 h) release from a point elevated non buoyant source of SF6. The hourly averaged concentrations were measured at 47 discrete sampling points. The mesoscale meteorological model, WRF was coupled with AERMOD to provide hourly surface and upper boundary layer meteorological parameters. The statistical evaluation of model was carried out using Fractional Bias (FB) and Normalized Mean Square Error (NMSE). The quantile-quantile (Q-Q) plot was used to assess model's ability to follow the observed concentration distribution. For this field tracer test the model over-predicted ground level concentrations at the receptors close to the source and underestimated at the receptors located in a valley and far away from the source. Moreover, AERMOD overestimated the concentration at receptors which were at the point of direct impaction of plume and ridge. Overall, the model under-predicted the ground level concentration within a factor of two (FB = 0.63) for this field tracer test. It was found that the model better simulated the higher concentrations which are of primary interest for regulatory purposes.

Analysis Method for Tracer Production Curve in Fractured-vuggy Reservoir

The fracture-vuggy carbonate reservoir in Tahe oilfield is unique and difficult to be analyzed by conventional tracer analysis technology. Based on the geological characteristics of fracture and vug in reservoirs, a theoretical model is established by applying fluent to simulate the flow characteristics of fluids in fracture-vug, so as to analyze the characteristics of tracers under different conditions: The output of tracer under the condition of single fracture shows kurtosis, while under the condition of single vug without kurtosis; The combination of many fractures can either enhance the peak height or show multiple peaks, while the combination of multiple vugs still shows no kurtosis but only extends the range; The output characteristics of series combination of fracture/vug were more influenced by themselves. The smaller the volume of vug is, the less the fractures were influenced, and thus the production becomes more and more similar to fractures; while the rest of them show vug characteristics. Through applying the tracer production curve analysis theory to the actual production data of the field tracer test, and establishing the fracture tunnel ratio and the dominant channel direction judgement method to characterize the reservoir flow path, we found that the ratio of the fracture and vug in the target area is 1:9; the direction of the dominant channel is determined by the size of the Interdistance intercepting area of the injection production well - the larger the section area is, the better the channel is. It indicates that the analytical method of tracer production curve in fracture-vug reservoir is applicable, and it can lay a foundation for improving the theory of tracer production characteristics analysis in fracture-vug reservoirs.

Numerical simulation of solute transport and structural analysis for groundwater connection medium based on the tracer test

AbstractSolute transport characteristics and groundwater connection structures are mainly studied in this paper by adopting the numerical simulation and field tracer test. Firstly, the simulation method of solute transport is proposed. Then two kinds of representative geological models of tracer test are built, and the process of solute transport is simulated. The variation characteristics of solute transport under the conditions of straight pipeline and branch pipeline are summarized by analysis of the simulation results. The effects of the pipeline width, flow velocity and path difference of branch pipelines on the tracer curve are discussed. General laws of groundwater connection tracer curve are obtained. Finally, based on the field test results, and combined with engineering geological conditions, characteristics of karst groundwater systems, the groundwater connection structures are analysed and speculated in detail by the flow velocity and local monitoring curve. The results show that: (i) As the flow velocity increases, the peak of the tracer curve decreases gradually, as well as the time to peak; (ii) The peak of the tracer curve gradually decreases with the increasing pipeline width; (iii) Under the different path difference of branch pipeline, the tracer curves all present obvious ‘trailing’ phenomenon; (iv) The analysis process of groundwater connection structures can provide references for the same type of hydrological geological problems.

Numerical methods and analysis for a multi-term time–space variable-order fractional advection–diffusion equations and applications

Field experiments of solute transport through heterogeneous porous and fractured media show that the growth of contaminant plumes may convert between diffusive states. In this paper, we propose a multi-term time–space variable-order fractional advection–diffusion model (MTT-SVO-FADM) to describe the underlying transport dynamics. We consider a numerical approach based on the implicit numerical method for numerical solution of this model. A fully-discrete numerical scheme is developed by using the classical finite difference method. The unconditional stability and convergence of the scheme are discussed and theoretically proved. We use a modified grid approximation method (MGAM) to estimate the model’s parameters. The MTT-SVO-FADM is then applied to describe transient dispersion observed at a field tracer test and four numerical experiments. The results show that this model can simulate the experimental data more accurately and can efficiently quantify these transitions. • A multi-term time–space variable-order fractional advection–diffusion model is proposed. • A fully-discrete numerical scheme is developed. • The unconditional stability and convergence of the scheme are discussed and proved. • A modified grid approximation method is used to estimate the model’s parameters. • This model is applied to describe transient dispersion observed at a field tracer test and four numerical experiments.

Disagreeing Evaluations for Slug Tests in Monitoring Wells: Importance of Standards

Hundreds of variable-head permeability (slug) tests were carried out in monitoring wells to assess the hydraulic conductivity, K, of an unconfined sand-and-gravel aquifer and, after that, the migration of contaminants. The pollution case has generated a legal dispute about the loss of many water supply wells and major health issues. The experts for the defendants had analyzed the slug test data with methods that differ from the standards. For the legal issues, the author reanalyzed all test data and made all verifications as required by standards. The new K values were about three times higher than the initial values obtained without respect to the standards, a major difference. The divergence was solved by studying the statistical distributions of K values. The initial values were too low to explain the high K values obtained with pumping tests, but the new K values correctly explained them. The new K values predicted groundwater velocity values at least three times higher than the initial values predicted with K values obtained without following the standards. These higher velocities were confirmed by field tracer tests performed by independent companies that designed and operated field pilot tests for decontaminating groundwater. The capacity to reconcile medium-scale tests (slug tests in monitoring wells) and large-scale tests (pumping tests in large wells) forms new evidence that strengthens the reasons for why it is important to follow the standards and make the required verifications.

Tracer Tests in Stratified Alluvial Aquifers: Predictions of Effective Porosity and Longitudinal Dispersivity versus Field Values

Tracer tests in aquifers are key tests to delineate protection perimeters around drinking water wells. They help to determine field values of effective porosity, ne, and longitudinal dispersivity, αL, from curve fitting to a breakthrough curve (BTC). It is difficult to predict ne, but correlations obtained with field or numerical tracer tests may be used to predict αL. The BTCs of field tracer tests differ from those predicted by the advection-dispersion theory in three ways: (1) early arrival with smaller than expected ne, (2) scale-dependent αL, and (3) a long thick tail. In this article, physical principles are used to obtain new closed-form predictive equations for ne and αL in stratified alluvial aquifers. The new equations give ne and αL for the hydraulically equivalent homogeneous aquifer. The predicted values for ne are shown to fit the field values of seven well-documented field tracer tests. The new equations explain the ne field values and can explain field values of αL for stratified aquifers, their variation with distance, and the variance of the ln(K) distribution. If the tracer is injected for a limited time, the predicted BTC also displays the three usual features of field data, which simply result from a lognormal K-distribution. The new equations and their experimental verification correctly elucidate some difficulties due to aquifer heterogeneity and improve our ability to predict groundwater movements in the subsurface.

Comparison of Time Nonlocal Transport Models for Characterizing Non-Fickian Transport: From Mathematical Interpretation to Laboratory Application

Non-Fickian diffusion has been increasingly documented in hydrology and modeled by promising time nonlocal transport models. While previous studies showed that most of the time nonlocal models are identical with correlated parameters, fundamental challenges remain in real-world applications regarding model selection and parameter definition. This study compared three popular time nonlocal transport models, including the multi-rate mass transfer (MRMT) model, the continuous time random walk (CTRW) framework, and the tempered time fractional advection–dispersion equation (tt-fADE), by focusing on their physical interpretation and feasibility in capturing non-Fickian transport. Mathematical comparison showed that these models have both related parameters defining the memory function and other basic-transport parameters (i.e., velocity v and dispersion coefficient D) with different hydrogeologic interpretations. Laboratory column transport experiments and field tracer tests were then conducted, providing data for model applicability evaluation. Laboratory and field experiments exhibited breakthrough curves with non-Fickian characteristics, which were better represented by the tt-fADE and CTRW models than the traditional advection–dispersion equation. The best-fit velocity and dispersion coefficient, however, differ significantly between the tt-fADE and CTRW. Fitting exercises further revealed that the observed late-time breakthrough curves were heavier than the MRMT solutions with no more than two mass-exchange rates and lighter than the MRMT solutions with power-law distributed mass-exchange rates. Therefore, the time nonlocal models, where some parameters are correlated and exchangeable and the others have different values, differ mainly in their quantification of pre-asymptotic transport dynamics. In all models tested above, the tt-fADE model is attractive, considering its small fitting error and the reasonable velocity close to the measured flow rate.

Hydrogeological controls of variable microbial water quality in a complex subtropical karst system in Northern Vietnam

Karst aquifers are particularly vulnerable to bacterial contamination. Especially in developing countries, poor microbial water quality poses a threat to human health. In order to develop effective groundwater protection strategies, a profound understanding of the hydrogeological setting is crucial. The goal of this study was to elucidate the relationships between high spatio-temporal variability in microbial contamination and the hydrogeological conditions. Based on extensive field studies, including mapping, tracer tests and hydrochemical analyses, a conceptual hydrogeological model was developed for a remote and geologically complex karst area in Northern Vietnam called Dong Van. Four different physicochemical water types were identified; the most important ones correspond to the karstified Bac Son and the fractured Na Quan aquifer. Alongside comprehensive investigation of the local hydrogeology, water quality was evaluated by analysis for three types of fecal indicator bacteria (FIB): Escherichia coli, enterococci and thermotolerant coliforms. The major findings are: (1) Springs from the Bac Son formation displayed the highest microbial contamination, while (2) springs that are involved in a polje series with connections to sinking streams were distinctly more contaminated than springs with a catchment area characterized by a more diffuse infiltration. (3) FIB concentrations are dependent on the season, with higher values under wet season conditions. Furthermore, (4) the type of spring capture also affects the water quality. Nevertheless, all studied springs were faecally impacted, along with several shallow wells within the confined karst aquifer. Based on these findings, effective protection strategies can be developed to improve groundwater quality.

Investigation of the hydraulic connection between the upper storage reservoir and the underground powerhouse in the Hongping Pumped Storage Hydroelectric Powerstation

Field tracer tests in fractured rocks were performed to investigate the hydraulic connection between the upper storage reservoir and the underground powerhouse in the Hongping Pumped Hydroelectric Storage Powerstation (HPHSP). Data from tracer measurement points indicated the appearance of multiple peak values during the course of tracer migration, which revealed multiple water pathways in fractured aquifers owing to the development and intersection of fractures and faults. Also, complex hydrogeological structural systems were proposed according to geological data from borehole logs and outcrops seen in the exploration adit. These structures revealed the different permeability and strong heterogeneity of the fractured media and can, therefore, explain the existence of a concentrated water-conducting passage from the upper storage reservoir to the underground powerhouse. Multiple peak values in the field tests were examined using a laboratory cross-fracture experiment involving tracer migration and numerical simulation based on transition probability. According to the observed data and the numerical results, the laboratory model and simulation method can capture the characteristics of groundwater flow and tracer migration in fractured rocks.

River-spring connectivity and hydrogeochemical interactions in a shallow fractured rock formation. The case study of Fuensanta river valley (Southern Spain)

In upland catchments, the hydrology and hydrochemistry of streams are largely influenced by groundwater inflows, at both regional and local scale. However, reverse conditions (groundwater dynamics conditioned by surface water interferences), although less described, may also occur. In this research, the local river-spring connectivity and induced hydrogeochemical interactions in intensely folded, fractured and layered Cretaceous marls and marly-limestones (Fuensanta river valley, S Spain) are discussed based on field observations, tracer tests and hydrodynamic and hydrochemical data. The differential flow measurements and tracing experiments performed in the Fuensanta river permitted us to quantify the surface water losses and to verify its direct hydraulic connection with the Fuensanta spring. The numerical simulations of tracer breakthrough curves suggest the existence of a groundwater flow system through well-connected master and tributary fractures, with fast and multi-source flow components. Furthermore, the multivariate statistical analysis conducted using chemical data from the sampled waters, the geochemical study of water-rock interactions and the proposed water mixing approach allowed the spatial characterization of the chemistry of the springs and river/stream waters draining low permeable Cretaceous formations. Results corroborated that the mixing of surface waters, as well as calcite dissolution and CO2 dissolution/exsolution, are the main geochemical processes constraining Fuensanta spring hydrochemistry. The estimated contribution of the tributary surface waters to the spring flow during the research period was approximately 26–53% (Fuensanta river) and 47–74% (Convento stream), being predominant the first component during high flow and the second one during the dry season. The identification of secondary geochemical processes (dolomite and gypsum dissolution and dedolomitization) in Fuensanta spring waters evidences the induced hydrogeochemical changes resulting from the allogenic recharge. This research highlights the usefulness of an integrated approach based on river and spring flow examination, dye tracing interpretation and regression and multivariate statistical analysis using hydrochemical data for surface water-groundwater interaction assessment in fractured complex environments worldwide, whose implementation becomes critical for an appropriate groundwater policy.

A MAR to address the water with high content of suspended solid with a case study in the Yellow River flood plain, China

Managed Aquifer Recharge (MAR) system is often adapted to alleviate drawdown cone and increase the water supply. In this study, an Open channel-Underground perforated pipe-Shaft system which included three identical subsystems was designed on the basis of local ditches, and applied at the Yellow River flood plain, Linqing city in North China. Three anti-clogging methods of the filter tank, inclined underground perforated pipe and shaft were adopted to lower the amount of fine suspended particles in source water. The dimensions and materials of each subsystem were tested and then determined by analytical method, numerical method and laboratory physical model experiment. The filter tank bottom area is 4m2, perforated pipe diameter of 30cm, length of 200m made from plastic blind drains wrapped with geo-textile and 20cm of coarse sand filled around, slope of 1/500, and the shaft depth of 10m. A pilot project was constructed in the study area covering 5.4hm2. Field recharge experiment and tracer test were conducted so as to monitor groundwater level and flow rate in perforated pipe. The measurements showed that the total infiltration amount attained from the field recharge experiment was 65,925m3, which was close to the simulation results by analytical and numerical methods; the average velocity in the perforated pipe between the inlet and the shaft was 150m/h approximately by both tracer test and theoretical calculation. This MAR project has the advantages of no energy consumption, no land occupation, managed groundwater recharge and water logging control. Therefore, its wider application in the location with similar conditions can be expected in future.

Longitudinal dispersion coefficient in ice-covered rivers

ABSTRACTThe focus of this paper is on the ice-cover effects on the longitudinal dispersion coefficient in rivers. The dispersion coefficients due to either the vertical or transverse velocity shear are calculated using Elder’s or Fisher’s triple integral equation, respectively, based on the assumptions of a parabolic cross section and a vertical logarithmic velocity distribution in both the riverbed and the ice-cover zones. The results show that in ice-covered natural rivers, where the aspect ratio is usually larger than 10, the dispersion coefficient due to the transverse velocity shear is 50 times greater than that due to the vertical velocity shear. An analytical formula for longitudinal dispersion coefficient is further developed by the simplification of Fischer’s triple integral equation, and it is validated against field tracer tests with discrepancy between observations and predictions less than 150%. Comparing the proposed formula to the most widely-used Fischer’s formula demonstrates that for wide and shallow rivers the presence of ice-cover will lead to about a three-fold increase in the magnitude of the longitudinal dispersion.

Field Tracer Test for the Design of LNAPL Source Zone Surfactant Flushing

AbstractA field tracer test was carried out in a light nonaqueous phase liquid (LNAPL) source zone using a well pattern consisting of one injection well surrounded by four extraction wells (5‐spot well pattern). Multilevel sampling was carried out in two observation wells located inside the test cell characterized by heterogeneous lithology. Tracer breakthrough curves showed relatively uniform flow within soil layers. A numerical flow and solute transport model was calibrated on hydraulic heads and tracer breakthrough curves. The model was used to estimate an average accessible porosity of 0.115 for the swept zone and an average longitudinal dispersivity of 0.55 m. The model was further used to optimize the relative effects of viscous forces versus capillary forces under realistic imposed hydraulic gradients and to establish optimal surfactant solution properties. Maximum capillary number (NCa) values between injection and extraction wells were obtained for an injection flow rate of 16 L/min, a total extraction flow rate of 20 L/min, and a surfactant solution with a viscosity of 0.005 Pa⋅s. The unconfined nature of the aquifer limited further flow rate or viscosity increases that would have led to unrealistic hydraulic gradients. An NCa range of 3.8 × 10−4 to 7.6 × 10−3 was obtained depending on the magnitude of the simulated LNAPL‐water interfacial tension reduction. Finally, surfactant and chase water slug sizing was optimized with a radial form of the simplified Ogata‐Banks analytical solution (Ogata and Banks 1961) so that injected concentrations could be maintained in the entire 5‐spot cell.

Combining 3D Hydraulic Tomography with Tracer Tests for Improved Transport Characterization.

Hydraulic tomography (HT) is a method for resolving the spatial distribution of hydraulic parameters to some extent, but many details important for solute transport usually remain unresolved. We present a methodology to improve solute transport predictions by combining data from HT with the breakthrough curve (BTC) of a single forced-gradient tracer test. We estimated the three dimensional (3D) hydraulic-conductivity field in an alluvial aquifer by inverting tomographic pumping tests performed at the Hydrogeological Research Site Lauswiesen close to Tübingen, Germany, using a regularized pilot-point method. We compared the estimated parameter field to available profiles of hydraulic-conductivity variations from direct-push injection logging (DPIL), and validated the hydraulic-conductivity field with hydraulic-head measurements of tests not used in the inversion. After validation, spatially uniform parameters for dual-domain transport were estimated by fitting tracer data collected during a forced-gradient tracer test. The dual-domain assumption was used to parameterize effects of the unresolved heterogeneity of the aquifer and deemed necessary to fit the shape of the BTC using reasonable parameter values. The estimated hydraulic-conductivity field and transport parameters were subsequently used to successfully predict a second independent tracer test. Our work provides an efficient and practical approach to predict solute transport in heterogeneous aquifers without performing elaborate field tracer tests with a tomographic layout.

Experimental Study of Heat Transport in Fractured Network

Fractured rocks play an important role in transport of natural resources through subsurface systems. In recent years, interest has grown in investigating heat transport by means of tracer tests, driven by the important current development of geothermal applications. Many field and laboratory tracer tests in fractured media show that fracture - matrix exchange is more significantfor heat than mass tracers, thus thermal breakthrough curves are strongly controlled by matrix thermal diffusivity. In this study, the behaviour of heat transport in a fractured network, at bench laboratory scale, has been investigated.