Delineating groundwater flow-paths in fractured aquifers under hazardous environment using conceptual and geophysical modeling with a case study

doi:10.21203/rs.3.rs-2367575/v1

Construction of landfills and open dumping of solid-waste above fracture-controlled aquifers can increase leachate concentrations, contaminating useable surface and shallow groundwater resources. In such cases, it is essential to define the hydrogeological processes and identify the pathways in the fractured aquifer system for contamination migration near the dumpsite. Abu Zaabal Quarry is a typical example where a solid-waste dumpsite was installed directly on fractured basalt around polluted groundwater ponds. To assess the vulnerability conditions in this complex environment, Seismic Refraction Imaging (SRI) and Electrical Resistivity Tomography (ERT) were integrated with the available geological and hydrogeological information for delineating the effective fractured zones and to refine the site conceptual model of the potential pathways associated with solid waste leachates,

The constructed resistivity and seismic images help to identify interflow zones in the basaltic protective zone and provide valuable information about the orientation and location of fractures feeding the ponds underneath the dumpsite. The presence of NW vertical fractures, which could provide a vertical hydraulic connection with the lower aquifer, allows the percolation of the leachate in the area around the dumpsite. These results show the advantage of using a combination of various geophysical methods for delineating the strikes of the prevailing fracture patterns and clarifying the pollution situation at typical composite landfills worldwide. The proposed conceptual groundwater flow model is critical for understanding hydrogeological and transport processes in such hazardous environments to achieve sustainable management of groundwater resources.

Dumpsite

Electrical Resistivity Tomography (ERT)

Seismic Refraction

fractured rock aquifers

Conceptual model

Fractured basaltic aquifer

Open and sanitary landfills are generally considered to be efficient and economical methods of waste disposal worldwide (El-Fadel et al., 1997; Osinowo et al., 2018; Scott et al., 2005; Srivastava and Chakma, 2022). A sanitary landfill is effectively isolated from the surrounding areas whereas the open dumpsite is not, with this free exchange of contaminates between the landfill and the surrounding environment, is observed in open dumps. Thus, leakage of leachates from the dumpsite into the subsoil and shallow groundwater might permeate through connected fractures, threatening the surrounding ecosystem and public health (Feng et al., 2020). Therefore, the selected site for landfills evidently considers numerous criteria including geological, hydrogeological, and geotechnical characteristics of the suggested site before construction (Allen, 2001; Arjwech et al., 2020; Fellner et al., 2009; Oweis and Khera, 1998; Shu et al., 2018). To reduce the environmental risk of the dumpsites, some regulations should be applied to prevent undesired migration of the leachates to the near-surface groundwater aquifers through vertical pathways such as fractures, fissures, faults, and connected permeable zones, as through the monitoring of transportation of leachates and their pathways delineation (Boateng et al. 2013, Abu Salem et al, 2021).

All over the world, open landfills and dumpsites are widely used as the primary facility for the ultimate disposal of municipal solid waste in fractured rocks; therefore, an inevitable consequence of this practice is leachate generation. Abu Zaabal quarries region in Egypt is a typical example of dumpsites in fractured basalt around surface water ponds (Fig. 1). In 1997, the quarries area was used as a solid waste dump in addition to industrial solid waste such as lead ashes, chemical waste, and rubbish which are gathered around the water ponds and led to an environmental disaster. These dumps were established over highly fractured basalt bedrock which represents an elevated hill around the ponds (Fig. 1). Therefore, the assessment of the environmental problem in the area is considered the main objective of several investigations to study the source and impact of the surficial contaminants and groundwater pollution (e.g. (Korany et al. 1993;Ahmed et al. 2005; El-Fakharany and Mansour 2013; Guda et al. 2020; El-Mathana et al. 2021). However, there is an increasing need to detect permeable pathways in fractured rock elsewhere in the vicinity of landfills for monitoring the contaminant transport and understanding the mechanism of the recharging system in the fractured hard-rock aquifers. In these aquifers, the first few meters are characterized by dense horizontal fractures and fissures, while the sub-horizontal and sub-vertical fractures are decreased with depth and the unweathered basaltic acts as a protective zone for the lower aquifers. Several hypothesizes have discussed the origin, structures, and hydrodynamic characterization of the crystalline rock aquifers (Banks et al., 2009; Cho et al., 2003; Dewandel et al., 2017, 2004; Lachassagne et al., 2021; Maréchal et al., 2004, 2002; Setlur et al., 2019; Worthington et al., 2016; Wyns et al., 2004). However, rare of these studies have produced complete evidence of the efficiency of basaltic rock as a protective layer for leachate migration that can provide valuable inputs related to the surface pollutants and groundwater movement and subsequently locate the preferential flow paths and extensions of lateral and vertical flow beneath landfills.

In such composite environments around landfills and disposal sites, site characterization investigations for continuous monitoring are essential to assess the possible pollution threats. Therefore, the assessment of vulnerability conditions and detection of the potential pathways (i.e. fractures, faults, and permeable zones) through which leachates could potentially percolate to shallow aquifers in the polluted area as in Abu Zaabal quarries are the usual objectives (Abu Salem et al., 2021). Thus, the delineation of the fractures patterns in the basaltic aquifers is essential for mitigation and control of leachates migration from sewage ponds, dumpsites, disposal systems, and other anthropogenic activities (Huan et al., 2020).

Geochemical, hydrogeological, and geotechnical techniques are the traditional methods of groundwater pollution investigation and leachate maps. However, these methods are costly, time-consuming, and labor-intensive (Zume et al., 2006) and thus gradually replaced by geophysical methods, which are non-invasive, much cheaper and facilitate rapid data acquisition with a high temporal and spatial resolution (Reynolds, 2011). Geophysical methods have become frequently successful in many environmental investigations as a significant tool for characterization, and long-term monitoring of waste disposal sites (Gemail 2012; Pujari et al. 2007; Soupios et al. 2007; Soupios and Ntarlagiannis 2017). A combination of different geophysical methods has been shown to be suitable for fractures mapping and tracing the preferential flow paths and extensions of lateral and vertical flow around landfills (Bowling et al. 2007; Schrott and Sass 2008; Chang et al. 2012; Gemail et al. 2017; Oudeika et al. 2020). Therefore, integrating and comparing the results from two or more geophysical methods allow a more detailed and robust image of the buried structures and contaminates flow paths where each method allows to detect of specific physical properties and/or structural features reducing the ambiguities characteristic in each method.

Accordingly, the electrical methods (i.e., DC resistivity, VLF, SP, and electromagnetic methods) are the most suitable tools for identifying high conductivity structures due to shallow groundwater and leachate flow in the fractured aquifer system. In contrast, the seismic and GPR methods are supportive to describe complex structural situations where the subsurface materials can change dramatically in a short distance (Gemail et al. 2004; Konstantaki et al. 2014; Shebl et al. 2019; Gemail et al. 2020; Youssef et al. 2021).

Reasonably, an integrative approach of Electrical Resistivity Tomography (ERT) and Seismic Refraction Imaging (SRI) were employed in the Abu Zaabal quarries region for detailed imaging of the vertical fracture sets in the exposed basaltic sheet around a solid waste dumpsite located near the surface water ponds (Fig, 1). The proposed multi-disciplinary geophysical approach was validated using the conceptual model of groundwater flow in the fractured aquifer and synthetic modeling of resistivity data to understand the groundwater flow regime in the front of the water ponds and landfill site.

More than fifty years ago, the quarry ponds were created due to the quarrying operations of basalt by the Abu Zaabal Quarry Company, and groundwater began to flow causing the origin of the ponds of surface water in the region, with increasing the level of water inside the ponds even equal with the water level of the Ismailia Canal. The basaltic quarries of the Abu Zaabal region are located about 30 km to northeast Cairo (Fig. 1). It covers about 2 km² to the west of the Ismailia Canal and is located at latitudes between 30.26° and 30.29°N, and longitudes 31.35° and 31.39°E in decimal degrees. To the east of the Abu Zaabal Quarries, an industrial area has been designated for the relocation of lead smelters and foundries from Cairo (Fig. 1c).

The Abu Zaabal area occupies a small part at the contact between the structural elevated ridges of Cairo-Suez Road to the south, and the eastern part of the Nile Delta-alluvial plain to the north (Said, 1990). The area has a smooth topography with elevations varying between 25 m (a.s.l) in the northeast of the large pond (Fig. 1b) and 18 m (a.s.l), in the south near the Ismailia Canal. As seen in Fig. (1b), the area between the Ismailia Canal and the surface ponds is characterized by the occurrence of a series of NW-SE elongated low relief ridges orientated perpendicular to the Ismailia Canal and alternating with in-between shallow elongated depressions. In addition, the ponds are bounded by NW-SE basaltic ridges.

Geologically, the area is located along the edge of the Nile Delta Quaternary sediments which consist of Pleistocene silt, sands, and gravels with lenses of clay. The Oligocene Basalt is exposed in the area surrounded by the Pleistocene sediments as illustrated in the surface geological map of Fig. (2). Abu Zaabal area occupies a small part at the contact between the structural elevated ridges of Cairo-Suez Road to the south, and the eastern part of the Nile Delta-alluvial plain to the north (Fig. 2). The basaltic sheet has an average thickness of 30 m and is underlined by fine-grained clayey and porous sandstones belonging to the Lower Oligocene (Fig. 3). The whole succession in the area is covered by an accumulation of Quaternary sands and silts of a variable thin thickness and increases northwards in the Delta plain (Said, 1990). Structurally, the area is affected by major faults and fractures trending NNW-SSE, NW-SE, and E-W (El-Dairy, 1980; El-Fayoumy, 1968; Elshazly et al., 1975; Shata, 1988).

From a hydrogeological point of view, the basaltic sheet is confined to the lower Oligocene sand aquifer. As seen in the geological cross-section of Fig. (3), the basaltic sheet is exposed around the quarries ponds and beneath the dumpsite due to normal faults that separate the Pleistocene sediment and the basalt to the east from the younger sediment to the west. Based on a series of geotechnical investigation boreholes drilled by Chemonics (Elansary et al., 2000) for assessing the geotechnical properties of the proposed industrial area, the area east of the exposed basalt is covered by the Miocene alluvium sand and gravels. The lead ashes and other industrial wastes are gathered and stocked in this sandy soil and fractured basalts without any precaution and may seep into the shallow groundwater rising the pollution risk in the area. In addition, the groundwater aquifer in the area is hydraulically connected with the Nile Delta Quaternary aquifer which is recharged mainly from the Ismailia Canal to the south of the dumpsite. According to El-Fakharany and Mansour (2013), new hydrogeological conditions are developed in Abu Zaabal Quarries. The deepening of the quarries and removal of the basaltic cap is associated with continuous groundwater flow, either from the Oligocene aquifer or leakage from the Ismailia Canal (Fig. 1b). In such a hazardous environment, the ponds and dumpsites may degrade the groundwater quality of the Quaternary and Oligocene aquifers due to the presence of the expected faults, fractures, and joints in the basalt, which helps the hydraulic connection between the surface ponds and the groundwater.

Jeannin and Grasso (1995) presented a conceptual model to demonstrate the water flow scheme in the epikarst or subcutaneous zone at the top of fractured aquifer system which is similar to the present case study of the Abu Zaabal basaltic aquifer. In this model (Fig. 4a), the near-surface epikarst layer is equivalent to the highly fissured alteration zone of the basalt due to extreme weathering which extends to 3–7 m depth below ground surface and is characterized by vertical and horizontal fracture networks (Fig. 4b) The perched water within this zone flows laterally through small conduits towards vertical major fractures with slow percolation. In this context, the unsaturated zone where a part of the water or leachates is stored and slowly released, which is considered as a low vulnerability based on the connection of the horizontal conduits (Fig. 4b) while, the rest quickly flow into the vertical fracture network increasing the aquifer vulnerability (Doerfliger et al., 1999; Doerfliger and Zwahlen, 1995; Williams, 2008).

Therefore, the vertical fracture sets in the area are the key feature for geophysical imaging in the present study where there is no detailed study has shown the linkage between the surface pollutants and groundwater around the dumpsites and Abu Zaabal ponds.

3.1. Data acquisition

Based on the geological setting of the area and conceptual model of water flow in fractured rocks (Fig. 4), the geophysical surveys were carried out in the front of the surface water ponds to characterize the fractures around the dumpsite and delineate the expected flow paths. Five vertical electrical soundings with Schlumberger array were carried out first to determine the thickness and the existence of basaltic sheet around the dumpsite (Fig. 1c). The maximum current electrode spacing (AB) was 300m which seems to be enough to penetrate the expected basaltic sheet and reaches the Oligocene sands. Additionally, thirty-one seismic profiles were measured in two perpendicular directions to detect the common fracture trends in the area (Fig. 1c). One from the northeast to the southwest parallel to the Ismailia Canal and another direction northwest to the southeast perpendicular to the first direction and also perpendicular to the Ismailia Canal (Fig. 1c). These profiles were carried out to measure the P-wave with 92 m long and geophone spacing of 4m. Single 28-Hz vertical geophones were used as receivers. The record length is 1024 ms with a 0.125 ms sampling rate. The acquired seismic data was done using a Seismograph of 24 channels (OYO MCSEIS-SX). Based on the seismic refraction results, six Dipole-Dipole (DD) ERT profiles were measured across the expected fracture strikes in the front of the dumpsite and the water ponds (Fig. 1c). The DD array is the most sensitive to horizontal changes in the subsurface resistivities such in the case of vertical structures like faults, and fractured zones which are common in the surveyed area. To reduce the systematic errors during measurements as much as possible, the ERT profiles were collected using Siber-48 (48 channels) multi-electrode automatic system with 235 m length and 5m minimum electrode distance. These parameters are suitable for imaging the vertical fractures in the basaltic sheet to a depth of 25 m. For data quality control (QC) during the field work, the apparent resistivities were collected with the standard deviation errors (Q %) from repeat cycles. The measurements with a standard deviation error of more than 5% were repeated or rejected.

3.2. Resistivity modeling and flow path conceptual model

To have cross-validation of all the geophysical data and the conceptual flow model, a synthetic modeling process was carried out to configure a 2D electrical resistivity signature of fractures along with the measured profiles. According to the conceptual flow model in Fig. (4), the fluid flow within the upper extremely weathered zone (equivalent to epikarst) has a lateral movement through small conduits towards vertical component with slow percolation into the tight horizontal fissures. This zone is defined as a temporary perched aquifer due to the fact that beneath this zone, the un-weathered basalt has lower permeability (Doerfliger et al., 1999). In contrast, the presence of vertical fractures at shallow depths near the dumpsite can significantly influence the lower aquifer recharge and contaminant transport (Goyal et al., 2021).

The conceptual model parameters (e.g., thickness of highly weathered zone, heterogeneities in the overburden, width and direction of fractures, and depth to the lower aquifer) were used in combination with the field observations as initial geological inputs to create the 2D synthetic model with the same survey parameters (Fig. 5). In the second step, 1D sounding points were inverted using IPI2WIN program Ver.3.0.1 (Bobachev et al., 2009) to determine the optimum thickness of the overburden and basaltic sheet. The inverted resistivities and layer thicknesses from 1D soundings and boreholes information were employed to build a 2D dipole-dipole model using the numerical modeling program of RES2DMOD Ver. 3.03 (Geotomo, 2018). The finite-difference algorithm was used to improve the calculated apparent resistivities at the nodes of the rectangular fine mesh in the horizontal direction to simulate the electrical response of vertical fractures and heterogeneities in the weathered basaltic sheet that control the flow paths and perched water around dumpsite and surface ponds (Fig. 5).

The 2D forward model represents vertical and declined fractures in the basalt overlain by highly weathered overburden. The calculated model was exported as data file with 5% arbitrary noise. Sequentially, the calculated 2D forward model was inverted using iterative robust and constrained least-squares algorithms in ZONDRES2D (Zond, 2018) and Res2Dinv (Geotomo, 2018) programs. The optimum inversion parameters were selected to image the suggested fracture sets. The final adjusted inversion parameters were saved in a file and read before starting the inversion of measured profiles around the dumpsite. The measured DD profiles were inverted and the resistivity response of vertical fractures can be clearly delineated compared with the prior synthetic model.

On the other hand, the seismic data were processed using the ZondST2d software (Zond, 2016) where the first arrivals were picked in interactive and semi-automatic modes for plotting travel time curves and velocity analysis. A band-pass filter was applied with a frequency range of 5 to 85 Hz to enhance the signal. In addition, the visible gains were applied to adequately recognize the first arrivals. The travel time curves were inverted using the smoothness-constrained algorithm to produce a 2D tomography section for interpretation and correlation with 2D ERT profiles.

4.1. Delineating the active groundwater flow-paths.

Delineating the fault/fracture zones in the basaltic bedrock typically involves the consideration of the thickness and nature of the highly weathered zone, which frequently contains gradient permeable paths over the basalt with vertical features and planar discontinuities. Accordingly, the permeability and water movement paths in the basaltic rocks are highly variable and depend mainly on the interconnected open spaces at the top and bottom of the basalt. In the basaltic sheet, the fractures and joints develop in the top unconsolidated zone and the permeability decreases gradually with the depth. Therefore, the inspection of the seismic profiles revealed three hydrogeological boundaries based on fractures/faults zones, water-table depth, and bedrock vertical channels (Fig. 6). The topmost zone is 3–7 m thick with a velocity ranging from 325 to 850 m/s, the second layer has a thickness of about 12 m and a velocity in the range of saturated zone (1200–1850 m/s), while in the deeper layer, the velocity is raised to > 3000 m/s due to low permeability in the basaltic bedrock (Fig. 6). The seismic signature of the velocity sections was comparable to the conceptual flow model (Fig. 4), where the velocity increases with increasing depth that corresponds to basaltic bedrock with sharp vertical channels. The direct comparison of the estimated water table and the measured water table in the borehole (BH2) shows the capability of seismic refraction tomography for determining the water table and delineation of aquifer boundaries (Fig. 6).

Table (1) lists the comparisons between the drilled borehole information by El-Mathana et al. 2021 and the current geophysical results in addition to the monitoring of water quality degradation close to the dumpsite and polluted water ponds. On the basis of the local depths of the saturated layers, as determined by the seismic velocity, the top of the water table was computed and presented in Fig. (7a) for a better understanding of the role of subsurface structures (joints, fractures, and faults) in recharging system and groundwater movement around the polluted ponds and dumpsite. In addition, the average depths to the basaltic bedrock as marker layer were estimated from the seismic lines as seen in the depth map of Fig. (7b).

Table (1)

Monitoring of water level and water quality from 1975 to current in the quarries pond and the close boreholes. The borehole BH5 was selected in the southwest outside the study area as reference point.

Water sample	Distance from dumpsite (m)	Ground Elevation (m)	Estimated depth to water table (m, a.s.l)			pH	Water Quality (mg/L)
			Borehole/ ponds	Seismic Refraction	ERT*		TDS	Cations				Anions			No3	COD^**
			Borehole/ ponds	Seismic Refraction	ERT*		TDS	Na	K	Mg	Ca	Cl	SO4	Hco3	No3	COD^**
Groundwater quality
BH1 (2019)¹	50 S	20.5	15.0	15.2	15.5	7.3	9656	127.5	27	272.3	316	2018.	2987.	218	21.7	47
BH2 (2019)¹	187 SW	20.6	15.3	15.0	15.4	5.5	9736	1927	28	297	369	2083	3115	236	--
BH3 (2019)¹	686 NE	17.2	12.7	11.9	12.3
BH4 (2019)¹	733 N	18.6	--	--	--	5.5	2752	540	14.5	81	152	306	25	270	0.35	47
BH5 (2021 )⁶	1760 SW					8.69	1251	93	11	42	212	231	153	30	-----
Monitoring of water quality in the large pond from 1975 to 2021
Large pond 1975²						7.7	846	----	----	----	----	199	----	-----	-----
Large pond 1993³						8.8	3500	758.7	11.6	425	332	3152	1215	732	-----
Large pond 1999⁴			7.51			7.16	3780									225
Large pond 2005⁵						8.18	4512	988	18	145	15.5	1346	1056	280.7	16.7
Large pond 2017⁶						8.26	11464	3069	51	263	431	2862	4343	Nil	Nil
Large pond 2019¹			11.3			7.8	14024	2614	31.7	353.4	310	3182	3585	172.7	130	238
Large pond 2021⁶			11.85			8.83	15702	4123	149	417	912	6685	3143	120	Nil

From:1 El-Mathana et al. 2021, 2- Abdel Aal 1975, 3- Korany et al. 1993, 4- Elansary et al. 2000, 5- Ahmed et al. 2005, and 6- Current study

* ERT Electrical Resistivity Tomography,

**COD Chemical Oxygen Demand

Both depth maps (Fig. 7) clearly identify the NW-SE structural framework of the shallow basaltic bedrock in the same direction of quarries ponds that is covered by the saturated highly fractured basalt and fills. As mentioned early in the topographic map (Fig. 1b), the NW-SE basaltic ridge is alternated by sedimentary depressions in the northeast and southwest boundaries of the quarries ponds. It is important note that the ponds are bounded by the same NW-SE trend, which is perpendicular to the Ismailia Canal. In this context, the water levels in the Ismailia Canal and the surface ponds are approximately equal (12.0 and 11.85 m a.s.l, respectively). This means that the Oligocene aquifer in the quarries ponds is directly connected to the Quaternary aquifer near the Ismailia Canal through vertical faults, fractures, and joints. According to the depth of the basaltic bedrock (Fig. 7b), the dumpsite and the ponds lie in a relatively low permeability basaltic zone. However, the presence of the highly weathered overburden and vertical fractures increases the hazardous situation in the area underneath the dumpsite and close to the ponds. As discussed in the conceptual model (Fig, 4), the highly weathered overburden is characterized by several horizontal fractures in the first few meters (3–7 m), while the density of these fractures is decreased with the depth. By focusing on fracture network connectivity around the dumpsite and the ponds, the waste leachates and highly polluted water from ponds move laterally through the horizontal fractures towards the lowlands of the exposed basalt as seen in the estimated water level map from seismic results (Fig. 7a).

Reasonably, the DD ERT profile-E6 was carried out perpendicular to the NW-SE basaltic ridge and close to the highly polluted large pond (Fig. 8). It is interesting to note that the area close to the ponds and dumpsite (SW end of DD profile in Fig. 8), a sharp decreasing trend in the resistivity is clearly observed at the same water level in the pond and close to the surface near the dumpsite where the TDS of water in the pond is about 15702 ppm. This very low resistivity anomaly (> 10 Ωm.) marks the negative impact of the highly fractured overburden below the dumpsite and the recharge’s pathway from the surface pond. Therefore, the resistivity distribution away from the pond indicates a gradually increasing trend to confirm the estimated flow paths from the seismic results (Fig. 7a) where the area around the surface ponds and dumpsite is considered as point-source of pollution in the whole area. In such a situation, the vertical fractures and faults detection is a key for a better understanding of leachates and groundwater flow in the area. It is worth noting that faults and vertical fractures can be seen as vertical low resistivity anomalies in the resistive basaltic bedrock (Fig. 8). The comparatively low resistivity anomalies in the basalt (20 to > 10 Ω m) of ridge-like structures might be related to the degree of saturation and high permeable materials that can favor leachate percolation and may act as a preferential flow path for recharging the lower sand aquifer as indicated from the vertical electrical sounding point (VES-4) at the NE end of DD profile-E6 (Fig. 8) where the resistivity decreases to > 10 Ωm. in the basal sand aquifer.

4.2. Impact of vertical fractures and conceptual model

The profile (E1) runs in the front of the dumpsite (Fig. 1) and cuts the southeastern edge of the NW-SE active trend (Fig. 7a) for imaging the vertical pathways that can act as pathways for surface pollutants and/or move the water from the Ismailia Canal to the water ponds. Comparing the DD and seismic profiles in Fig. (9), it can be seen that the profiles are coherent and compatible for detecting the vertical fractured zones. Along the DD section (Fig. 9a), several resistivity features are observed that can be classified into two resistivity sets: the overburden appears as a horizontal shallow zone with low resistivity and rests on more complex high resistivity at the depth indicated by fractured basalts. The basal high resistivity layer intersecting with the vertical low resistivity sharp patterns is interpreted as saturated fractured zones. These fractured zones are the most compelling trends that feed water sources in the ponds passing beneath the dumpsite. It is clear that the low resistivity overburden is characterized by a maximum thickness (> 15 m) in the eastern part of the profile and becomes thinner to the west where the basaltic bedrock arises to the surface around the ponds due to the faulting system in the middle part. Accordingly, the shallow western bedrock increases the local appearance of perched water (hanging water) as explained early in the conceptual flow model in the fractured rocks of Figs. (4 and 5). The jointed results of ERT and SRI profiles show that a highly fracture/fault zone exists in the middle part and extends to the west as illustrated with the connected grey polygon in Fig. (9). The presence of such vertical pathways increases the possible pollution threats where the leachates could potentially percolate to shallow aquifers. In such a composite environment around dumpsite or landfills, site characterization investigations for continuous monitoring are essential to assess the possible pollution threats. Therefore, the assessment of vulnerability conditions and detection of the potential pathways (i.e. fractures, faults, and permeable zones) through which leachates could potentially percolate to shallow aquifers in the polluted area as in Abu Zaabal Quarries are the usual objectives (Abu Salem et al. 2021; Gemail 2015; Gemail et al. 2017).

To the west of the first profile (E1), the profile (E5) runs on the southeast edge of the dumpsite and perpendicular to the primary trend of the small pond (Fig. 1c). As seen in Fig. (10), the incorporation of the 2D-ERT and seismic sections along this profile identified the main vertical fractured zone in the middle part and extends towards the east. The significant variation of resistivity values in the top surface layer reflects the heterogeneities of weathered basalts where the western side has high values from 50 to 153 Ωm. due to the shallow basalt bedrock. In contrast, the eastern parts are characterized by low resistivity values between 10 and 25 Ωm. due to the dominance of fine materials and highly weathered basalt which extends to 15 m depth. The basaltic bedrock is revealed below the highly weathered overburden on the eastern side with a resistivity value of 150 Ωm. Whereas, the descent and height of the basaltic bedrock are controlled by the fracture/ fault sets in the area (Fig. 10). At a distance of 140–180 m along with the DD profile, a vertical low resistivity anomaly extending downwards, a shape that can be related to a major fracture zone connecting the surface with the subsurface in the front of the dumpsite. Accordingly, the advantage of the DD array can be noticed through the sharp boundaries of fractures where it is sensitive to the vertical structures as in the present case; in addition, the DD array subsequently follows fractures throughout with depth (Loke et al., 2013). All seismic and ERT profiles were inspected using the same approach to distinguish the active flow path trends around the dumpsite and water ponds.

To delineate the preferential vertical pathways in the basalt around the dumpsite, the parallel DD profiles were compiled with its perpendicular line (E4) as presented in Fig. (11). The pseudo-3D visualization in Fig. (11) clearly shows the orientation and location of the near-surface vertical fractures and faults that connect the highly weathered overburden with horizontal permeability and lower aquifer. The near-vertical resistivity contrast in all ERT profiles sections with an NW-SE orientation is consistent with the accepted topographical, geological, and hydrogeological information of the area where this trend is the perpendicular to Ismailia Canal (Fig. 1b). In the highlands around the ponds and the dumpsite, internal faulting in the basalt may account for the appearance of vertical offsets and some of the variation in the thickness and nature of the overburden. The low resistivity discontinuities divide the basaltic bedrock into blocks which reflect the changing in water content and fillings. In the topmost zone, the resistivity distributions display low values of 15 Ωm at the surface in the front of the dumpsite (E1, E2, and E3, respectively in Fig. 11) where clay-rich soils, weathered basalt, and perched water are more conductive. In contrast, these values increase up to 100 Ωm far away from the ponds along E6 (15 m depth) due to the low water content in the uplands of basalt. These results are well correlated with the water table and estimated bedrock depth maps from seismic refraction (Fig. 7).

Based on the integrated results of geophysical data and field observation, a conceptual hydrogeological model of groundwater and leachates flow through fractured basalt is presented in Fig. (12). This conceptual flow model comprises an upper weathered basalt, an intermediate layer of densely fractured basalt and a deep layer of poorly fractured rock with NW-SE sub-vertical fracture zones. The highly weathered overburden with horizontal permeability gradient is connected with the deeper layer through the vertical fractures and faults. In such case, the aquifer vulnerability for wastewater and leachates is a function of the fracture permeability of the overlying weathered basalt and rock column around the polluted ponds and dumpsite. Thereby, the constructed model is similar to that discussed by (Dewandel et al., 2017; Jeannin and Grasso, 1995; Lachassagne et al., 2021; Maréchal et al., 2004; Wyns et al., 2004) and provides a simplified representation of the spatial heterogeneity in the fractured aquifer and the suspicions on the permeability associated with weathering and fractured basalt (Fig. 4). The understanding and illustration of the obtained conceptual model allowed to development of a comprehensive quantity of applied geophysical approaches in the hydrogeology of fractured aquifers and vulnerability mapping under hazardous environments. This conceptual model with geophysical results improves the quantitative water resources management, modeling, and protection of fractured aquifers close to point sources of pollution,

In addition, the current results of geophysical interpretation are correlated well with the borehole information and the recent research results of El-Mathana et al. 2021 using the mass transport model to simulate the leachates flow nearby the dumpsite. This correlation indicated that the leachate mainly affects the water quality of the surface ponds and groundwater by a radius of approximately 1–2 Kilometers where the ponds and the dumpsite are located in the uplifted basalt with horizontal fractures (low permeability gradient) that delayed the leachate and limited its flow extent. El-Mathana et al. 2021 discussed the future scenarios using comprehensive simulation and numerical groundwater modeling and indicated that the dumpsite needs to be closed to not receive any further solid waste, in addition to reduce the pumping from the nearby wells to delay the vertical circulation of pollutants through the vertical fractures (Fig. 12).

The comparison between developed conceptual flow model and geophysical data demonstrates that the combination of electrical resistivity tomography and seismic refraction methods with field observations can improve the understanding of hydrogeological processes in the deeper zone and the calibration of the corresponding leachates flow model in the overburden fractured zone (Fig. 12). Therefore, the identification of spatial subsurface vertical structures (i.e. fractures and/or faults) is even a more critical for developing the conceptual flow model in the fractured bedrock under impact of hazardous environments as in the current case study.

Understanding the main hydrological processes in hazardous environments as establishing landfills, dumpsites, and wastewater disposal in fractured bedrock is of critical importance for building a suitable management strategy of pollutants and water resources conservation. In the Abu Zaabal open quarries, an integrated interpretation of geophysical data with field observation and borehole information was carried out to define the location, orientation, and extent of fractures in basaltic bedrock underlying the dumpsite; and refine the site conceptual flow model that describes the groundwater and leachates movements in the area.

In the current approach, the preliminary field observations and 1D resistivity interpreted results were employed effectively to build a synthetic model reflecting the dominated fractures and the conceptualization of water circulation processes in the overburden subsoils. The synthetic modelling of geological and hydrogeological settings is of weighty value for the inversion of ERT profiles where the optimum inversions parameters were adapted based on the suggested model for imaging the vertical pathways in the overburden and the few meters of the basalt. The combined ERT and seismic refraction methods have proved their efficiency for delineating such geological structures. The DD sections illustrate the deeper vertical fractures in the basalt that act as a preferential flow path for the perched wastewater and leachates beneath the dumpsite. It is clear that the ERT and seismic sections illustrated the same anomalies that were detected by both supplementary methods in addition to the lateral heterogeneities in the highly weathered overburden. Accordingly, the conductive anomalies around the waste dumpsite are interpreted to extend vertically through the overburden, into the shallow basalt bedrock, and laterally to the lowlands nearby the dumpsite (approximately 1–2 km around the dumpsite).

The joint use of seismic and resistivity imaging indicates the major fracture strike directions in basalt bedrock are generally oriented nearly NW-SE and NE-SW perpendicular to the Ismailia freshwater canal. These results complement what is known of the local geology and geomorphology of the basalt outcrops in the ponds. These vertical zones connect the lower Oligocene aquifer and the near-surface overburden and act as high vulnerability zones in the area. According to the ERT and seismic refraction sections, the water table depth varies between 4-6m below the ground surface (13–15 m.a.s.l) in the area nearby the dumpsite, while the perched water and leachates are appeared over the shallow impermeable basalt subsoil as hanging water zone. Therefore, the withdrawal of water through artesian wells in the north and north east of the region leads to an increase in the speed of pollutants through the vertical fractures therefore care must be taken to deal with this part and any contaminants or wastes must be far away and take more protective action.

Data Availability

The datasets generated during and/or analysed during the current study are available from the corresponding author on reasonable request.

Competing interests

The authors declare no competing interests.

Author Contributions

This work was made possible by significant contributions from all authors. KH. G, and A. Gh. Conceptualization, Methodology (ERT and Seismic), Validation, Formal analysis (Geophysical data modeling), Data Curation (geophysical metadata. Writing - Review & Editing the final MS, Visualization, Supervision the research team. K.E., Sh S, and S., Sh. Data Curation (geophysical metadata), Visualization, Supervision. A.S Conceptual modeling and Geological interpretation., Writing—Review & editing the final MS. All authors contributed critically to the drafts and gave final approval for publication. All authors have read and agreed to the published version of the manuscript.

Abdel Aal, A.Y., 1975. Geological study on Abu Zaabal basalts of Egypt. M.Sc. Thesis. Ain Shams University, Cairo, Egypt.
Abu Salem, H., Gemail, K.S., Nosair, A.M., 2021. A multidisciplinary approach for delineating wastewater flow paths in shallow groundwater aquifers: A case study in the southeastern part of the Nile Delta, Egypt. J Contam Hydrol 236, 103701. https://doi.org/10.1016/J.JCONHYD.2020.103701
Ahmed, M.A., El-Hemamy, S.T., Abd El-Samie, S.G., 2005. Sources of water emanating from the quarrying locations in Abu Zaabal area, Egypt. Al-Azhar Bull Sci 16, 39–54.
Allen, A., 2001. Containment landfills: the myth of sustainability. Eng Geol 60, 3–19. https://doi.org/10.1016/S0013-7952(00)00084-3
Arab Society of Mining and Petroleum, 1970. Scientific and applied symposium on groundwater in Egypt, part II, Nile Valley and Delta. Bull. 25, Cairo (in Arabic).
Arjwech, R., Somchat, K., Pondthai, P., Everett, M., Schulmeister, M., Saengchomphu, S., 2020. Assessment of Geological, Hydrogeological and Geotechnical Characteristics of a Proposed Waste Disposal Site: A Case Study in Khon Kaen, Thailand. Geosciences 2020, Vol. 10, Page 109 10, 109. https://doi.org/10.3390/GEOSCIENCES10030109
Banks, E.W., Simmons, C.T., Love, A.J., Cranswick, R., Werner, A.D., Bestland, E.A., Wood, M., Wilson, T., 2009. Fractured bedrock and saprolite hydrogeologic controls on groundwater/surface-water interaction: a conceptual model (Australia). Hydrogeol J 17, 1969–1989.
Boateng, E., Asare, V.-D.S., Danuor, S., 2013. Detection and Delineation of Contaminant Migration using the Terrain Conductivity Technique outside the Perimeters of the Dompoase Landfill Facility in Kumasi–Ghana. Journal of Environment and Earth Science 3, 13–24.
Bobachev, A., Modin, I., Shevinin, V., 2009. IPI2Win V2. 0: User’s Guide. Department of Geophysics, Moscow State University. Moscow State 452.
Bowling, J.C., Harry, D.L., Rodriguez, A.B., Zheng, C., 2007. Integrated geophysical and geological investigation of a heterogeneous fluvial aquifer in Columbus Mississippi. J Appl Geophy 62, 58–73. https://doi.org/10.1016/J.JAPPGEO.2006.08.003
Chang, P.-Y., Chen, C., Chang, S.-K., Wang, T.-B., Wang, C.-Y., Hsu, S.-K., 2012. An investigation into the debris flow induced by Typhoon Morakot in the Siaolin Area, Southern Taiwan, using the electrical resistivity imaging method. Geophys J Int 188, 1012–1024. https://doi.org/10.1111/j.1365-246X.2011.05310.x
Cho, M., Choi, Y., Ha, K., Kee, W., Lachassagne, P., Wyns, R., 2003. Relationship between the permeability of hard rock aquifers and their weathering, from geological and hydrogeological observations in South Korea, in: International Association of Hydrogeologists Conference on «Groundwater in Fractured Rocks.
CONOCO, 1987. Geological map of Egypt 1:500,000, in: Klitzsch, E., List, F.K., Pohlmann, G. (Eds.), Map Sheets NH36NW and NH35NE. CONOCO with Cooperation of the Egyptian General Petroleum Corporation, Cairo.
Dewandel, B., Alazard, M., Lachassagne, P., Bailly-Comte, V., Couëffé, R., Grataloup, S., Ladouche, B., Lanini, S., Maréchal, J.-C., Wyns, R., 2017. Respective roles of the weathering profile and the tectonic fractures in the structure and functioning of crystalline thermo-mineral carbo-gaseous aquifers. J Hydrol (Amst) 547, 690–707.
Dewandel, B., Lachassagne, P., Qatan, A., 2004. Spatial measurements of stream baseflow, a relevant method for aquifer characterization and permeability evaluation. Application to a hard‐rock aquifer, the Oman ophiolite. Hydrol Process 18, 3391–3400.
Doerfliger, N., Jeannin, P.-Y., Zwahlen, F., 1999. Water vulnerability assessment in karst environments: a new method of defining protection areas using a multi-attribute approach and GIS tools (EPIK method). Environmental Geology 39, 165–176. https://doi.org/10.1007/s002540050446
Doerfliger, N., Zwahlen, F., 1995. EPIK: a new method for the delineation of protection areas in karstic environment, in: International Symposium on Karst Waters and Environmental Impacts, Antalya, Turkey. pp. 117–123.
Elansary, A., BrownL, P.E., Larochelle, R., 2000. Landfill Development and Operations Plan for the Abou-Zaabal Quarry in the Governorate. CAIP, Cairo Air Improvement Project Lead Pollution Abatement Component. USAID Contract No. 263-C-00-97-00090-00, USAID/Egypt, Office of Environment.
El-Dairy, M.D., 1980. Hydrogeological studies on the eastern part of Nile Delta using isotope techniques. M.Sc. Thesis, El-Azhar Univ., Egypt. A master thesis submitted to Zagazig Uni., Egypt.
El-Fadel, M., Findikakis, A.N., Leckie, J.O., 1997. Modeling leachate generation and transport in solid waste landfills. Environ Technol 18, 669–686.
El-Fakharany, M.A., Mansour, N., 2013. Using modflow and MT3D groundwater flow and transport models as a management tool for the Quaternary aquifer, East Nile Delta, Egypt. Int. J. Sci. Comm. Human 1.
El-Fayoumy, I.F., 1968. Geology of groundwater supplies in the region east of the Nile Delta. Ph.D. Thesis, Cairo Univ., Egypt.
El-Mathana, M.E., Mostafa, N.G., Galal, M.M., Elawwad, A., 2021. Assessment and simulation of a solid waste dumpsite impact on the surrounding water resources: A case study in Abu Zaabal, Egypt. Heliyon 7, e08421. https://doi.org/10.1016/J.HELIYON.2021.E08421
Elshazly, E.M., Abdel-Hady, M.A., Elshazly, M.M., Elghawaby, M.A., Elkassas, I.A., Salman, A.B., Morsi, M.A., 1975. Geological and groundwater potential studies of El Ismailiya master plan study area. R.S.R. project, Academy Sci., R.T. Cairo.
Fellner, J., Döberl, G., Allgaier, G., Brunner, P.H., 2009. Comparing field investigations with laboratory models to predict landfill leachate emissions. Waste Management 29, 1844–1851. https://doi.org/10.1016/J.WASMAN.2008.12.022
Feng, S.J., Zhao, Y., Zhang, X.L., Bai, Z.B., 2020. Leachate leakage investigation, assessment and engineering countermeasures for tunneling underneath a MSW landfill. Eng Geol 265, 105447. https://doi.org/10.1016/J.ENGGEO.2019.105447
Gemail, K., Samir, A., Oelsner, C., Mousa, S.E., Ibrahim, S., 2004. Study of saltwater intrusion using 1D, 2D and 3D resistivity surveys in the coastal depressions at the eastern part of Matruh area, Egypt. Near Surface Geophysics 2, 103–109. https://doi.org/DOI: 10.3997/1873-0604.2004007
Gemail, Kh.M.S., 2012. Monitoring of wastewater percolation in unsaturated sandy soil using geoelectrical measurements at Gabal el Asfar farm, northeast Cairo, Egypt. Environ Earth Sci 66, 749–761. https://doi.org/10.1007/s12665-011-1283-6
Gemail, K.S., 2015. Application of 2D resistivity profiling for mapping and interpretation of geology in a till aquitard near Luck Lake, Southern Saskatchewan, Canada. Environ Earth Sci 73, 923–935. https://doi.org/10.1007/s12665-014-3441-0
Gemail, K.S., Attwa, M., Eleraki, M., Zamzam, S., 2017. Imaging of wastewater percolation in heterogeneous soil using electrical resistivity tomography (ERT): a case study at east of Tenth of Ramadan City, Egypt. Environ Earth Sci 76, 666. https://doi.org/10.1007/s12665-017-7013-y
Gemail, K.S., Shebl, S., Attwa, M., Soliman, S.A., Azab, A., Farag, M.H., 2020. Geotechnical assessment of fractured limestone bedrock using DC resistivity method: a case study at New Minia City, Egypt. NRIAG Journal of Astronomy and Geophysics 9, 272–279. https://doi.org/10.1080/20909977.2020.1734999
Geotomo, 2018. Manual RES2DINV Ver. 3.4. Penang, Malaysia, Geotomo Software.
Goyal, D., Haritash, A.K., Singh, S.K., 2021. A comprehensive review of groundwater vulnerability assessment using index-based, modelling, and coupling methods. J Environ Manage 296, 113161. https://doi.org/10.1016/J.JENVMAN.2021.113161
Guda, A.M., El-Hemaly, I.A., Abdel Aal, E.M., Odah, H., Appel, E., el Kammar, A.M., Abu Khatita, A.M., Abu Salem, H.S., Awad, A., 2020. Suitability of magnetic proxies to reflect complex anthropogenic spatial and historical soil heavy metal pollution in the southeast Nile delta. Catena (Amst) 191, 104552. https://doi.org/10.1016/J.CATENA.2020.104552
Huan, H., Li, X., Zhou, J., Liu, W., Li, J., Liu, B., Xi, B., Jiang, Y., 2020. Groundwater pollution early warning based on QTR model for regional risk management: A case study in Luoyang city, China. Environmental Pollution 259, 113900. https://doi.org/10.1016/J.ENVPOL.2019.113900
Jeannin, J.Y., Grasso, A.D., 1995. Recharge respective des volumes de roche peu perméable et des conduits karstiques, rôle de l’épikarst. Bulletin d’hydrogéologie 95–111.
Konstantaki, L.A., Ghose, R., Draganov, D., Diaferia, G., Heimovaara, T., 2014. Characterization of a heterogeneous landfill using seismic and electrical resistivity data. Geophysics 80, EN13–EN25. https://doi.org/10.1190/geo2014-0263.1
Korany, E.A., Shendi, E.H., Abdel Tawab, S., 1993. Integrated detection of the problem of groundwater overflow in Abu Zaabal Basalt Quarries, Egypt, in: EGS Proceedings of the 11th Annual Meeting. pp. 161–180.
Lachassagne, P., Dewandel, B., Wyns, R., 2021. Hydrogeology of weathered crystalline/hard-rock aquifers—guidelines for the operational survey and management of their groundwater resources. Hydrogeol J 1–34.
Loke, M.H., Chambers, J.E., Rucker, D.F., Kuras, O., Wilkinson, P.B., 2013. Recent developments in the direct-current geoelectrical imaging method. J Appl Geophy 95, 135–156. https://doi.org/10.1016/J.JAPPGEO.2013.02.017
Maréchal, J.-C., Dewandel, B., Subrahmanyam, K., 2004. Use of hydraulic tests at different scales to characterize fracture network properties in the weathered‐fractured layer of a hard rock aquifer. Water Resour Res 40.
Maréchal, J.C., Sarma, M.P., Ahmed, S., Lachassagne, P., 2002. Establishment of earth tide effect on water-level fluctuations in an unconfined hard rock aquifer using spectral analysis. Curr Sci 83, 61–64.
Osinowo, O.O., Falufosi, M.O., Omiyale, E.O., 2018. Integrated electromagnetic (EM) and Electrical Resistivity Tomography (ERT) geophysical studies of environmental impact of Awotan dumpsite in Ibadan, southwestern Nigeria. Journal of African Earth Sciences 140, 42–51. https://doi.org/10.1016/J.JAFREARSCI.2017.12.026
Oudeika, M.S., İlkimen, E.M., Taşdelen, S., Aydin, A., 2020. Distinguishing Groundwater Flow Paths in Fractured Rock Aquifers Formed Under Tectonic Stress Using Geophysical Techniques: Cankurtaran Basin, Denizli, Turkey. Int J Environ Res 14, 567–581. https://doi.org/10.1007/s41742-020-00279-w
Oweis, I.S., Khera, R.P., 1998. Geotechnology of waste management, PWS Pub. Co.
Pujari, P.R., Pardhi, P., Muduli, P., Harkare, P., Nanoti, M. v., 2007. Assessment of pollution near landfill site in Nagpur, India by resistivity imaging and GPR. Environ Monit Assess 131, 489–500. https://doi.org/10.1007/s10661-006-9494-0
Reynolds, J.M., 2011. An introduction to applied and environmental geophysics. John Wiley & Sons.
Said, R., 1990. The Geology of Egypt, The Geology of Egypt. Routledge. https://doi.org/10.1201/9780203736678
Schrott, L., Sass, O., 2008. Application of field geophysics in geomorphology: Advances and limitations exemplified by case studies. Geomorphology 93, 55–73. https://doi.org/10.1016/J.GEOMORPH.2006.12.024
Scott, J., Beydoun, D., Amal, R., Low, G., Cattle, J., 2005. Landfill management, leachate generation, and leach testing of solid wastes in Australia and overseas. Crit Rev Environ Sci Technol 35, 239–332.
Setlur, N., Sharp, J.M., Hunt, B.B., 2019. Crystalline-rock aquifer system of the Llano Uplift, Central Texas, USA. Hydrogeol J 27, 2431–2446.
Shata, A.A., 1988. Geology of Cairo, Egypt. Environmental & Engineering Geoscience 149–183.
Shebl, S., Gemail, K.S., Attwa, M., Soliman, S.A., Azab, A., Farag, M.H., 2019. Utilizing shallow seismic refraction in defining the geotechnical properties of the foundation materials: A case study at New Minia City, Nile Valley, Egypt. Egyptian Journal of Petroleum 28, 145–154. https://doi.org/10.1016/J.EJPE.2018.12.006
Shu, S., Zhu, W., Wang, S., Ng, C.W.W., Chen, Y., Chiu, A.C.F., 2018. Leachate breakthrough mechanism and key pollutant indicator of municipal solid waste landfill barrier systems: Centrifuge and numerical modeling approach. Science of The Total Environment 612, 1123–1131. https://doi.org/10.1016/J.SCITOTENV.2017.08.185
Soupios, P., Ntarlagiannis, D., 2017. Characterization and monitoring of solid waste disposal sites using geophysical methods: Current applications and novel trends, in: Sengupta, D., Agrahari, S. (Eds.), Modelling Trends in Solid and Hazardous Waste Management. Springer, pp. 75–103.
Soupios, P., Papadopoulos, N., Papadopoulos, I., Kouli, M., Vallianatos, F., Sarris, A., Manios, T., 2007. Application of integrated methods in mapping waste disposal areas, in: Environmental Geology. pp. 661–675. https://doi.org/10.1007/s00254-007-0681-2
Srivastava, A.N., Chakma, S., 2022. Bioreactor landfills: sustainable solution for disposal of municipal solid waste, in: Advanced Organic Waste Management. Elsevier, pp. 315–328.
Williams, P.W., 2008. The role of the epikarst in karst and cave hydrogeology: A review. Int J Speleol 37, 1–10.
Worthington, S.R.H., Davies, G.J., Alexander Jr, E.C., 2016. Enhancement of bedrock permeability by weathering. Earth Sci Rev 160, 188–202.
Wyns, R., Baltassat, J.-M., Lachassagne, P., Legchenko, A., Vairon, J., Mathieu, F., 2004. Application of proton magnetic resonance soundings to groundwater reserve mapping in weathered basement rocks (Brittany, France). Bulletin de la Société géologique de France 175, 21–34.
Youssef, Y.M., Gemail, K.S., Sugita, M., AlBarqawy, M., Teama, M.A., Koch, M., Saada, S.A., 2021. Natural and Anthropogenic Coastal Environmental Hazards: An Integrated Remote Sensing, GIS, and Geophysical-based Approach. Surv Geophys 42, 1109–1141. https://doi.org/10.1007/s10712-021-09660-6
Zond, 2018. ZondRes2D software for 2D resistivity and IP imaging (land, borehole and marine variants). Zond Geophysical Software, Saint-Petersburg. Last update: 1 Feb 2018.
Zond, 2016. Zond ST2D software for 2D seismic data processing and interpretation (surface, borehole and marine variations). Zond geophysical software Saint-Petersburg 2001-2016. Last update: 23 January 2018.
Zume, J.T., Tarhule, A., Christenson, S., 2006. Subsurface Imaging of an Abandoned Solid Waste Landfill Site in Norman, Oklahoma. Groundwater Monitoring & Remediation 26, 62–69. https://doi.org/10.1111/J.1745-6592.2006.00066.X

No competing interests reported.

Delineating groundwater flow-paths in fractured aquifers under hazardous environment using conceptual and geophysical modeling with a case study

Status:

Version 1

Abstract

Figures

1. Introduction

2. Geological And Hydrogeological Site Characterization

3. Methodology

3.1. Data acquisition

3.2. Resistivity modeling and flow path conceptual model

4. Results

4.1. Delineating the active groundwater flow-paths.

4.2. Impact of vertical fractures and conceptual model

5. Discussion

6. Conclusion

Declarations

References

Additional Declarations

Status:

Version 1