Underground Area Research Articles

Application of Geomechanical Classification Systems in a Tourist Mine for Establishing Strategies within 3G’s Model

Stability problems in rock masses are one of the main causes of subsidence events in underground mining areas. Zaruma, in the South of Ecuador, is characterised by mineral wealth, in which 65% of the population depends directly on artisanal mining activity. However, mineral extraction, without technical considerations and in many cases illegal, has negatively impacted the stability of tunnels generated under the city’s urban area, reporting subsidence events in recent years. The aim of this study is to geomechanically characterise the main gallery of the tourist mine “El Sexmo” using two classic methods of geomechanical classification for the configuration of a model that complies with the 3G’s (geotourism, geoconservation, and geoeducation) and supports the culture of sustainability in all areas of the sector. The methodology consists of (i) a field study design, (ii) a geological–geomechanical survey of the rock mass of a tourist mine using rock mass rating (RMR) and the Q-Barton index, and (iii) establishing a 3G’s model for sustainable development. The results reveal that 100% of the rock mass of the tourist mine presents a rock quality classified as “Fair” (class III) by the RMR method, while, via the Q-Barton method, 92.9% of the rock mass obtains a “Poor” rating, except for station S05, rated “Very Poor”. Furthermore, the study proposes additional support measures for three specific stations based on Q-Barton assessments, including fibre-reinforced sprayed concrete and bolting and reinforced ribs of sprayed concrete, considering that the mine is more than 500 years old and maintains geological features for geoeducation in geotechnical mining. Technical and social problems demand an innovative strategy, which, in this work, focuses on the 3G’s model based on the quintuple innovation helix to develop sustainable underground geotourism.

Identification and Spatiotemporal Migration Analysis of Groundwater Drought Events in the North China Plain

Groundwater droughts can explain developments and changes in groundwater from a climatological perspective. The North China Plain (NCP) is a typical underground funnel area. Therefore, groundwater drought studies in the NCP can provide better understanding of the local hydrogeological characteristics from new perspectives. In this paper, the GRACE groundwater drought index (GGDI) was used to evaluate groundwater drought events in the NCP. Additionally, a new method was proposed in this study for investigating groundwater drought events at the spatiotemporal scale. On this basis, the centroid theory was used to construct an appropriate groundwater drought migration model for the NCP. The results showed that (1) the groundwater drought frequency in the NCP was 24.54%. In addition, the most severe groundwater drought events in the study occurred in March 2020. (2) In total, 49 groundwater drought events occurred in the NCP over the 2003–2020 period. The most intense groundwater drought event occurred over the June 2018–December 2020 period (DE.49), covering the entire study area. DE.29 was the second most intense groundwater drought event over the August 2012–September 2013 period (14 months), resulting in a maximum arid area of 75.57% of the entire study area. (3) The migration of the groundwater drought events was in the southwest–northeast and northeast–southwest directions, which was consistent with the terrain inclination, while most of the groundwater drought centroids were concentrated in Area II. The groundwater drought event identification method and the groundwater drought migration model were effective and reliable for assessing groundwater drought events in the NCP and provided a better understanding of developments and changes in groundwater droughts, which is of great practical significance and theoretical value for the rational development and use of groundwater resources, as well as for guiding industrial and agricultural activities.

Monitoring the subsidence at different periods in high underground water level coal mine areas using differential interferometric synthetic aperture radar (D-InSAR)

Monitoring the subsidence at different periods in high underground water level coal mine areas can provide a data basis for land reclamation. For the purpose of monitoring subsidence in I working face located in Guotun Coal Mine, 22 Sentinel-1 images were processed by using differential interferometric synthetic aperture radar (D-InSAR). After dividing subsidence periods, the characteristics and monitoring accuracy at different subsidence periods were explored. The results showed that: (1) The formation of single-gradient subsidence funnel is an important sign to identify active period. (2) The root mean square error (RMSE) and mean absolute error (MAE) in central area of subsidence are reduced by 50% and 49%, respectively, compared with those in edge area. (3) The monitoring accuracy is high at different subsidence periods. The coefficient of determination (R2) can reach more than 0.89. Therefore, D-InSAR technique can accurately monitor the subsidence at different periods based on Sentinel-1 data.

A Comprehensive Study of the Suitability of Urban Underground Spaces for Connection Development: A Case Study of the Erhai Lake Basin, China

Urban underground space (UUS) involves multiple stakeholders whose concerns span the entire life cycle of underground space. The government pays more attention to the social benefits of UUS to the region, developers pay more attention to the economic benefits brought by the development of UUS, and users pay more attention to the comfort level of UUS operation. This study used the analytic Hierarchy Process (AHP), government, developers, and users to construct a comprehensive evaluation index system of underground space development needs. Different from previous studies, considering the need for future connectivity development in the UUS circle, this paper proposes to comprehensively consider the impact of connectivity development on regional suitability through coupled AHP and cellular automata (CA). The results show that about 102.67 km2 (13.03%) underground area of Erhai Lake Basin is suitable for underground space development. Compared with the traditional evaluation method, the evaluation result of about 31.41 km2 (3.99%) area was improved, and the fragmentation problem between blocks was improved. This method is of great value to the comprehensive development of UUS in the Erhai Lake Basin and is helping to improve future underground space planning.

Shear behavior and damage evolution of the interface between rough rock and cemented tailings backfill

The shear behavior of the interface between rock and cemented tailings backfill (CTB) is extremely critical to the backfill design and stability of the backfilled underground mined-out areas. The corresponding shear behavior and surface damage can be significantly affected by the roughness of the rock surfaces. In our study, sandstone with the same rough surface were prepared using rock engraving technology. The direct shear tests on the rough rock-CTB interfaces were carried out under four different normal stresses and six different roughness of the rock surfaces. The interfacial shear strength and corresponding surface damage were analyzed. A new shear strength criterion of the rough rock-CTB interface was then proposed and verified. Our study shows that the compressive deformation of the combined specimen is much larger than that of dilatancy under a higher normal stress. The residual shear strength is less affected by the rock surface roughness under lower normal stress. The corresponding shear strength of the rough rock-CTB interface does not necessarily increase with the rock surface roughness due to the large strength difference between the sandstone and CTB. The interfacial damaged zones, which increase with the normal stress, are roughly concentrated in the larger concave section of the corresponding 2D profiles. The established shear strength criterion of the rock-CTB interface consists of basic mechanical and morphology parameters which can be easily estimated by the general laboratory tests. The findings obtained from this study can be used to quantify the effect of the rough rock-CTB interface on the stability of CTB.

Ground Deformation Monitoring over Xinjiang Coal Fire Area by an Adaptive ERA5-Corrected Stacking-InSAR Method

Underground coal fire is a global geological disaster that causes the loss of resources as well as environmental pollution. Xinjiang, China, is one of the regions suffering from serious underground coal fires. The accurate monitoring of underground coal fires is critical for management and extinguishment, and many remote sensing-based approaches have been developed for monitoring over large areas. Among them, the multi-temporal interferometric synthetic aperture radar (MT-InSAR) techniques have been recently employed for underground coal fires-related ground deformation monitoring. However, MT-InSAR involves a relatively high computational cost, especially when the monitoring area is large. We propose to use a more cost-efficient Stacking-InSAR technique to monitor ground deformation over underground coal fire areas in this study. Considering the effects of atmosphere on Stacking-InSAR, an ERA5 data-based estimation model is employed to mitigate the atmospheric phase of interferograms before stacking. Thus, an adaptive ERA5-Corrected Stacking-InSAR method is proposed in this study, and it is tested over the Fukang coal fire area in Xinjiang, China. Based on original and corrected interferograms, four groups of ground deformation results were obtained, and the possible coal fire areas were identified. In this paper, the ERA5 atmospheric delay products based on the estimation model along the LOS direction (D-LOS) effectively mitigate the atmospheric phase. The accuracy of ground deformation monitoring over a coal fire area has been improved by the proposed method choosing interferograms adaptively for stacking. The proposed Adaptive ERA5-Corrected Stacking-InSAR method can be used for efficient ground deformation monitoring over large coal fire areas.

Removal of NO at low concentration from air in urban built environments by activated miscanthus biochar

This work presents an innovative and sustainable approach to remove NO emissions from urban ambient air in confined areas (underground parking areas or tunnels) using low-cost activated carbons obtained from Miscanthus biochar (MSP700) by physical activation (with CO2 or steam) at temperatures ranging from 800 to 900 °C. The NO removal capacity of the activated biochars was evaluated under different conditions (temperature, humidity and oxygen concentration) and compared against a commercial activated carbon. This last material showed a clear dependence on oxygen concentration and temperature, exhibiting a maximum capacity of 72.6% in air at 20 °C, whilst, its capacity notably decreased at higher temperatures, revealing that physical NO adsorption is the limiting step for the commercial sample that presents limited oxygen surface functionalities. In contrast, MSP700-activated biochars reached nearly complete NO removal (99.9%) at all tested temperatures in air ambient. Those MSP700-derived carbons only required low oxygen concentration (4 vol%) in the gas stream to achieve the full NO removal at 20 °C. Moreover, they also showed an excellent performance in the presence of H2O, reaching NO removal higher than 96%. This remarkable activity results from the abundance of basic oxygenated surface groups, which act as active sites for NO/O2 adsorption, along with the presence of a homogeneous microporosity of 6 Å, which enables intimate contact between NO and O2. These features promote the oxidation of NO to NO2, which is further retained over the carbon surface. Therefore, the activated biochars studied here could be considered promising materials for the efficient removal of NO at low concentrations from air at moderate temperatures, thus closely approaching real-life conditions in confined spaces.

High-Resolution Quasi-Three-Dimensional Transient Electromagnetic Imaging Method for Urban Underground Space Detection

Transient electromagnetic (TEM) method is a geophysical technique suitable for efficient detection of urban underground space, which can be used for advance detection of road collapse and underground water inrush accidents. In actual urban geological detection, engineers hope to be able to quickly characterize the underground space in 3-D, so as to assess the potential underground subsidence area or water inrush area risk. However, due to the complexity of urban geology, it is difficult for conventional 3-D imaging techniques to take into account both imaging efficiency and imaging accuracy. To address this issue, this article proposes a fast, high-resolution TEM quasi-3-D imaging strategy suitable for urban geology. We convert the TEM data into pseudoseismic wavelet data to identify the geological correlation of the 3-D spatial survey area, and then impose adaptive spatial constraints on the 3-D imaging. Simulation and application case results show that, compared with conventional imaging techniques, our proposed new strategy can effectively improve imaging resolution while ensuring computational efficiency. The research results provide a feasible technical solution for rapid high-resolution 3-D detection of urban geology.

The Synergistic Effect of Topographic Factors and Vegetation Indices on the Underground Coal Mine Utilizing Unmanned Aerial Vehicle Remote Sensing.

Understanding the synergistic effect between topography and vegetation in the underground coal mine is of great significance for the ecological restoration and sustainable development of mining areas. This paper took advantage of unmanned aerial vehicle (UAV) remote sensing to obtain high-precision topographic factors (i.e., digital elevation model (DEM), slope, and aspect) in the Shangwan Coal Mine. Then, a normalized difference vegetation index (NDVI) was calculated utilizing Landsat images from 2017 to 2021, and the NDVI with the same spatial resolution as the slope and aspect was acquired by down-sampling. Finally, the synergistic effect of topography and vegetation in the underground mining area was revealed by dividing the topography obtained using high-precision data into 21 types. The results show that: (1) the vegetation cover was dominated by "slightly low-VC", "medium-VC", and "slightly high-VC" in the study area, and there was a positive correlation between the slope and NDVI when the slope was more than 5°. (2) When the slope was slight, the aspect had less influence on the vegetation growth. When the slope was larger, the influence of the aspect increased in the study area. (3) "Rapidly steep-semi-sunny slope" was the most suitable combination for the vegetation growth in the study area. This paper revealed the relationship between the topography and vegetation. In addition, it provided a scientific and effective foundation for decision-making of ecological restoration in the underground coal mine.

Groundwater Vulnerability and Delineation of Protection Zones in the Discharge Area of a Karstic Aquifer—Application in Agyia’s Karst System (Crete, Greece)

This work represents a contribution to the protection techniques of karst aquifers against groundwater pollution. The paper sets out the methodology being introduced for the protection of the karstic system that gives rise to five (5) major groups of springs and supplies fourteen (14) pumping wells near Agyia Chania (Crete, Greece). Starting from a geological and hydrogeological survey of the area, the work presents a vulnerability assessment of the karstic aquifer based on the application of three index-based methods (EPIK, PRESK and DRISTPI). The protection zones for the discharge area of the aquifer were delineated through an integrated geomorphological approach and groundwater flow modeling. At first, the risk of polluting substances migration from ground surface to groundwater was considered based on the spatial distribution of vulnerability. Following this, the vulnerability was evaluated in the saturated zone, where the attenuation mechanisms of contaminants were reducing due to the raised flow velocity. The groundwater flow and contaminant transport processes was considered using the MODFLOW code. Next, the data from the vulnerability mapping and the groundwater flow simulation were merged into an integrated assessment to delimit the protection zones for the water abstraction points. The vulnerability assessment outlines zones of high vulnerability in the SE part of the area, far away from the discharge zone of the aquifer and the water abstraction points. These zones are associated with an intensive infiltration process via carbonate formations. Protection Zone I was delineated 20 m around the water abstraction points, and it should be excluded from any anthropogenic activity. Protection Zone II coves part of the very high and high vulnerability zones defined by the DRISTPI method (located upwards of the water abstraction points), as well as an area downwards of springs and wells, where the flow path lines which demonstrate the subsurface travelling time of 50 days are projected to the ground surface. Protection Zone III extends outside Zone Ι and Zone ΙΙ, up to the limits of the hydrogeological or hydrological basin, whichever is larger. It includes the entire capture zone (i.e., the surface and underground catchment area) that feeds the water abstraction points. In this manner the protection zones include the entire contributing area to water abstraction points, not just the ground surface recharge zone.

Machine learning model for predicting blast fume dilution time in underground working areas

ABSTRACT In underground mines, accurate prediction of dilution time is crucial to protect miners from toxic fumes as well as minimize production delays and ventilation costs. Previous researchers have used empirical equations, mine ventilation software, and computational fluid dynamics to calculate dilution time. These traditional methods have high computational cost and design limitations. In this research, machine learning (ML) techniques and data analytics were used to: (i) develop a ML model to predict dilution time based on five on-site blasting and auxiliary ventilation parameters and (ii) determine the order of importance of these parameters. The advantages of using the ML model over the traditional methods are its ability to consider a large number of factors, detect complex nonlinear relationships, and predict the dilution time near-instantaneously. Results show that the normalized artificial neural network has the best prediction capability with an R 2 of 0.987. Among the blasting and ventilation parameters measured, air volumetric flow rate significantly affected the dilution time, followed by duct distance from face and the amount of explosive.

Fast Detection and Classification of Dangerous Urban Sounds Using Deep Learning

Video analytics is an integral part of surveillance cameras. Compared to video analytics, audio analytics offers several benefits, including less expensive equipment and upkeep expenses. Additionally, the volume of the audio datastream is substantially lower than the video camera datastream, especially concerning real-time operating systems, which makes it less demanding of the data channel’s bandwidth needs. For instance, automatic live video streaming from the site of an explosion and gunshot to the police console using audio analytics technologies would be exceedingly helpful for urban surveillance. Technologies for audio analytics may also be used to analyze video recordings and identify occurrences. This research proposed a deep learning model based on the combination of convolutional neural network (CNN) and recurrent neural network (RNN) known as the CNN-RNN approach. The proposed model focused on automatically identifying pulse sounds that indicate critical situations in audio sources. The algorithm’s accuracy ranged from 95% to 81% when classifying noises from incidents, including gunshots, explosions, shattered glass, sirens, cries, and dog barking. The proposed approach can be applied to provide security for citizens in open and closed locations, like stadiums, underground areas, shopping malls, and other places.

Low-Cost GNSS Simulators With Wireless Clock Synchronization for Indoor Positioning

In regions where global navigation satellite systems (GNSS) signals are unavailable, such as underground areas and tunnels, GNSS simulators can be deployed for transmitting simulated GNSS signals. Then, a GNSS receiver in the simulator coverage outputs the position based on the received GNSS signals (e.g., Global Positioning System (GPS) L1 signals in this study) transmitted by the corresponding simulator. This approach provides periodic position updates to GNSS users while deploying a small number of simulators without modifying the hardware and software of user receivers. However, the simulator clock should be synchronized to the GNSS satellite clock to generate almost identical signals to the live-sky GNSS signals, which is necessary for seamless indoor and outdoor positioning handover. The conventional clock synchronization method based on the wired connection between each simulator and an outdoor GNSS antenna causes practical difficulty and increases the cost of deploying the simulators. This study proposes a wireless clock synchronization method based on a private time server and time delay calibration. Additionally, we derived the constraints for determining the optimal simulator coverage and separation between adjacent simulators. The positioning performance of the proposed GPS simulator-based indoor positioning system was demonstrated in the underground testbed for a driving vehicle with a GPS receiver and a pedestrian with a smartphone. The average position errors were 3.7 m for the vehicle and 9.6 m for the pedestrian during the field tests with successful indoor and outdoor positioning handovers. Since those errors are within the coverage of each deployed simulator, it is confirmed that the proposed system with wireless clock synchronization can effectively provide periodic position updates to users where live-sky GNSS signals are unavailable.

Development of stability criteria for risk reduction in the Desa Kubang Tangah in Sawahlunto Indonesia

Sawahlunto City is one of 19 cities/regencies in West Sumatra Province that is highly vulnerable to landslides. The topography is steeply wavy, including in Kubang Tangah village, Lembah Segar subdistrict. The city already has a land use plan that limits urban development. During the Dutch East Indies government, Sawalunto was known as a coal mining city. This city did not develop for a time after coal mining stopped. Studies that provide scientific considerations are needed, considering that this city has limited land, is prone to landslides, and is an underground mining area. As such, geological studies and geotechnical investigations are carried out to obtain the necessary data, followed by an analysis of the potential for landslides in the Kubang Tangah village area, which, in April 2023, experienced a landslide disaster resulting in road infrastructure and several houses being damaged. Furthermore, based on the analysis of safety factor criteria using the limit equilibrium method, which compares driving forces and slope-resisting forces, it is proposed to be considered in plans to develop settlements and road infrastructure to reduce the risk of landslides.

A Novel Pressure Relief Hole Recognition Method of Drilling Robot Based on SinGAN and Improved Faster R-CNN

The drilling robot is the key equipment for pressure relief in rockburst mines, and the accurate recognition of a pressure relief hole is the premise for optimizing the layout of pressure relief holes and intelligent drilling. In view of this, a pressure relief hole recognition method for a drilling robot, based on single-image generative adversarial network (SinGAN) and improved faster region convolution neural network (Faster R-CNN), is proposed. Aiming at the problem of insufficient sample generation diversity and poor performance of the traditional SinGAN model, some improvement measures including image size adjustment, multi-stage training, and dynamically changing iteration times are designed as an improved SinGAN for the generation of pressure relief hole images. In addition, to solve the problem that the traditional depth neural network is not ideal for small-size target recognition, an improved Faster R-CNN based on multi-scale image input and multi-layer feature fusion is designed with the improved SqueezeNet as the framework, and the sample data collected from ground experiments are used for comparative analysis. The results indicate that the improved SinGAN model can improve the diversity of generated images on the premise of ensuring the quality of image samples, and can greatly improve the training speed of the model. The accuracy and recall rate of the improved Faster R-CNN model were able to reach 90.09% and 98.32%, respectively, and the average detection time was 0.19 s, which verifies the superiority of the improved Faster R-CNN model. To further verify the practicability of the proposed method, some field images were collected from the underground rockburst relief area in the coal mine, and a corresponding test analysis was carried out. Compared with three YOLO models, the accuracy and recall rate of improved Faster R-CNN model improved significantly, although the training time and recognition time increased to a certain extent, which proves the feasibility and effectiveness of the proposed method.

Research into the coal quality with a new selective mining technology of the waste rock accumulation in the mined-out area

Purpose. The research purpose is to study the formation of quantitative-qualitative indicators of mined coal under conditions of dynamic changes in space and time with a new stope mining technology with waste rock accumulation in the underground mined-out area. Methods. The contours are formed for mining low-thickness coal reserves and extracting thicknesses, undercut rock volumes in the stoping and preparatory faces in the conditions of the Heroiiv Kosmosu mine. The average density values of coal, rock layers and wall rocks in the seam within the boundaries of mining contours are determined based on the geological data of wells and mining operations. The graphic basis is executed in the AutoCAD program. A digital spatial model of the С10t seam contours is used, according to the schedule for organizing stope and preparatory operations. The volumes of waste rocks and minerals involved in the formation of quantitative-qualitative rock mass indicators in a given time period are calculated. Findings. It has been determined that during mining of coal reserves from the studied mining area (equal to extraction site), the volume of production and the operational coal ash content in the mining technology with waste rock accumulation averages 376.5 thousand tons and 15.2%, while with traditional technology – 621.3 thousand tons and 46.7%. Nevertheless, it has been proven that in terms of energy equivalent, the value of mined coal using the mining technology with waste rock accumulation is higher by 7.4% than the traditional technology (9.6 TJ versus 8.9 TJ). Originality. For the first time, a mechanism for the formation of operational ash content and energy value of coal has been revealed when combining the processes of drifting operations to prepare reserves from new extraction pillars with associated stope operations into a new selective mining technology with waste rock accumulation in the mined-out area. Practical implications. An algorithm for predicting the operational ash content and quality of coal when using selective mining technology with waste rock accumulation in the mined-out area has been developed, which is important for the technical and economic indicators of coal mines.

Study on the Application of Elastic Wave CT Technique to Detect the Effect of Post-Grouting of Pile Foundation

The post-grouting technology can effectively improve the bearing capacity and reliability of foundation piles, and it is of great academic and economic significance to evaluate the effect of post-grouting. However, in general, the evaluation of the effect of post-grouting slurry on foundation piles is still relatively single, and most researchers only test the improvement of the bearing characteristics of post-grouting piles, but there are few research results on the distribution state of slurry consolidation and the range of the reinforced soil. In this paper, elastic wave CT was used to detect the bridge piles of Taizhou Bay Du Xiaipu Bridge, and elastic wave CT technology was applied to the detection of the post-grouting effect of foundation piles experimentally. The spatial distribution characteristics of the underground grouting reinforcement area were revealed from the perspective of visualization, and the influencing factors of the elastic wave inversion results were analyzed. The conclusions obtained from elastic wave CT detection were similar to those of electromagnetic wave CT, and the laws are basically consistent with the current engineering experience, reflecting the applicability of using elastic wave CT to detect the effect of post-grouting of pile foundation.

Research on the Control Process of Mining and Combustion Disturbance Zone Based on the Three-Dimensional Dynamic Distribution Model of Void Fraction

ABSTRACT The cavities formed by the combustion of underground coal fires and the overlying rock damage caused by the combustion will cause the surface to subside or even collapse, forming crisscrossing surface cracks. On the basis of studying the fracture, subsidence and caving characteristics of overlying strata in the coal seam mining-combustion composite open space, the temporal and spatial development of the coal seam mining-combustion composite open space and the three-dimensional movement law of the induced overlying rock are studied in order to build three-dimensional dynamic theoretical distribution model of porosity in coal seam mining and combustion disturbance zone. Based on the porosity evolution model, the fire zone isotope radon method is used to detect the temperature anomalous area in the goaf. According to the location of the abnormal high-temperature area, a comprehensive treatment method is carried out, which is mainly based on the combined grouting of the upper and lower the mine, and supplemented by nitrogen injection and three-phase foam injection, thereby to solve the problem of difficult quantitative characterization of the multi-void medium in the mining-influenced underground coal fire area and targeted treatment for coal fire prevention and control in the mining-combustion disturbance area.

Methodology for the estimation of mining face stresses using rock core diametrical deformation

In-situ stress measurements usually take place away from the underground mine work areas to capture the pre-mining stress tensor. However, mining face stresses around drifts, ramps, and stopes in underground mines are quite different from pre-mining stresses due to the excavations created by mining activities and the presence of geological structures. Therefore, investigating the development of an effective and practical method to estimate mining-induced stresses near a mining face should prove useful in practice. This study presents a simple and practical methodology based on rock core deformations for determining mining-induced stresses near underground mine openings, such as drifts and crosscuts where the near-field stresses in the sidewalls, the back, and the face could be of concern to the stability of the opening. The analytical solution developed in this paper can be used to determine the major and minor principal stresses near the mine opening in a plane perpendicular to the borehole axis and parallel to the free mining face. The analytical solution has been validated with published test results of laboratory experiments on rock cores extracted while subjected to uniaxial compression. It is shown that the results presented by the proposed method agree well with the applied stresses measured in laboratory experiments.

A Virological Perspective on the Use of Bacteriophages as Hydrological Tracers

Hydrological tracers, commonly used for characterizing water flow paths and sources, do not often meet all the requirements of an ideal tracer. Trans-disciplinary approaches are advocated as the way forward to enlarge the number of tracers available for investigating hydrological processes. Since the 19th century, hydrological tracers have been increasingly used, particularly in underground areas. The tracer toolbox at hand includes a large variety of options, including fluorescent dyes, isotopes, salts or bacteriophages, with each tracer offering specific qualities and complementarities. While their potential for hydrological studies has been studied in karstic environments since the 1960s, bacteriophages remain insufficiently understood. According to the selection methodology used in this review, more than thirty experiments have been listed, involving in total around seventeen different bacteriophages. These have facilitated the investigation of groundwater, surface water (i.e., river, lake and marine water), wetland and wastewater hydrological processes. The tracing experiments have also highlighted the possible interaction between bacteriophages and the surrounding environments. Bacteriophages have successfully helped researchers to understand the water flow within watersheds. Certain advantages, such as the sensitivity of detection, the ease of producing high concentrations of bacteriophages to be injected, their specificity for a host and their non-pathogenicity for human and animal cells, make bacteriophages appreciable tracer candidates for tracing experiments. However, the adsorption process or environmental factors such as temperature, pH and UV light considerably impact the fate of bacteriophages, thereby leading to an attenuation of the phage signal. Considering both the flaws and the qualities of bacteriophages, their use as hydrological tracers requires new insight and further discussions regarding experimental tracing conditions.