Regional characteristics of hydraulic parameters of the rocks of the Brezovské Karpaty Mts.

Determination of hydrological properties of the aquifer is of fundamental importance in hydrogeological and geotechnical studies. An attempt has been made to refine the hydraulic conductivity values computed from the pumping test by utilizing the hydraulic values computed in the laboratory. This study uses hydraulic conductivity computed in the laboratory of rock samples, pumping test data in conjunction with the empirical equations, and vertical electric sounding (VES) to determine the hydraulic properties of Lower Bari Doab (LBD) in the Indus Basin of Pakistan. The utilized dataset comprises pumping test results (Kpump) from 17 water wells, hydraulic conductivity values (Klab) of different grain size subsurface lithologies, and 50 VES stations. To this end, the investigated area is divided into 17 polygons by using the Thiessen technique, and equal distribution/weight of conductivities values is assigned to 17 polygons (one polygon around each water well where pumping test is conducted). The true resistivity ranging from 20–90 ohm-m along with an average thickness of the aquifer is computed using the VES data for each polygon. A novel approach has been developed to estimate the hydraulic conductivity of the aquifer by combining laboratory data and pumping test which is used to compute the other hydraulic properties. The calculated hydraulic conductivity, transmissivity, and tortuosity values of the aquifer range from 4.4 to 85.6 m/day, 674 to 8986 m2/day, and 13 to 20, respectively. The porosity ranges from 32 to 45% and the formation factor values fall in the range 4 to 12. Higher hydraulic conductivities were encountered in the southern portion of the area near the junction of the rivers, and it increases with an increase in porosity. The aquifer having T > 5700 m2/day and K > 40 m/day, yields a large quantity of water whereas the portion of an aquifer with T < 1100 m2/day and K < 13 m/day are combatively low yield aquifer. The results of the resistivity method show that the subsurface geological material, as depicted from true resistivity, is composed of layers of sand, clay, and silt mixed with gravel/sand. This study improves the understanding of the aquifer and will help in the development and management of groundwater resources in the area including the prediction of future behavior of the aquifer.

Aquifer hydraulic parameters including hydraulic conductivity and transmissivity play a very important role in the assessment and management of groundwater. Conventionally, these parameters are best estimated employing pump test, which is usually expensive and time-consuming. The use of surficial electrical resistivity data integrated with few available pumping test data provides a cost-effective and efficient alternative. A total of thirty-five (35) vertical electrical soundings with a maximum half-current electrode spacing of 150m using the Schlumberger array were used in this study. Five (5) of these soundings were parametric soundings carried out in the vicinity of monitoring wells for correlation and comparative purposes. The empirical relationships between the hydraulic parameters derived from the pump test data and the aquifer resistivity data were established for the Ebonyi and Abakaliki Formations, respectively, and, in turn, used to estimate aquifer hydraulic parameters in areas away from wells. Aquifer hydraulic conductivity estimated across the study area varies from 0.49 to 1.5735m/day with a mean value of 0.9205m/day for the Ebonyi Formation, while the Abakaliki Formation has hydraulic conductivity values that vary from 0.0775 to 1.3023m/day, with a mean value of 0.2883m/day. The transmissivity values estimated across the study area range between 0.29 and 57.27 m2/day with a mean value of 6.59 m2/day. Transmissivity values obtained were interpreted with Krásný's transmissivity classification, and this delineated the study area into three groundwater potential zones: very low, low, and intermediate zones. The study shows that the areas underlain by the Ebonyi Formation have a higher groundwater potential than those underlain by the Abakaliki Formation. These findings are supported by the geology of the area, which revealed that the Abakaliki Formation is dominated by shales with very low permeability, while the Ebonyi Formation consists of shales with alternations of sand/sandstones, which statistical analysis of the different model equations used in estimating the hydraulic parameters of the study area revealed that the new model empirical equations proposed and used in the present study proved to be the best alternatives to pumping test data.

Kachia Local Government Area (LGA) is located at the southern part of Kaduna State, Nigeria. Quantitative and qualitative appraisals were carried out in order to have proper understanding of the aquifer system and ensure sustainable development by using geophysical, geological and pumping test data obtained from 32 producing boreholes across the entire LGA. Hydraulic conductivity, transmissivity and storativity values were computed, piezometric surface map and the basement relief map were prepared, geoelectric layer characteristics were delineated and two geological profile sections were constructed. The hydraulic conductivity values were found to range from 0.021 m/day at Walijo to 1.391 m/day at Iddah-Hanya with an average of 0.42 m/day. The transmissivity values ranged between 0.90 m²/day at Walijo to 25.37m²/day at Iddah-Hanya, with average value of 6.31 m²/day. Storativity values were lowest at Walijo with a value of 89.42 and highest at Iddah-Hanya having a value of 2877 with an average of 929.82. The lowest values of these three aquifer constants were observed to converge at Walijo at the extreme eastern part and they all peaked at Iddah Hanya on the western border of the study area. The piezometric surface contour map showed that static water level is generally deeper around the central part of the study area than at the southern and western parts. The basement relief map revealed that the depth to Basement rock is generally deeper at the central part than at the eastern, western and southern boundaries of the study area. Three-layer geoelectric horizons delineated agreed with the drilled sections. The two profile sections 1 and 2 suggested that the weathered layer constituted the major aquiferous unit, and it occurred within a depth of 1 m to as much as 35 m, except Kurmin-Sara with 80 m thickness. Groundwater prospecting can therefore be targeted to an approximately uniform regolith thickness across the entire study area.

The influence of eight factors on hydraulic parameters (transmissivity, hydraulic conductivity, specific capacity, specific capacity index and maximum yields) are analysed, with data based on hydrogeological reports of 298 wells in dolomite aquifers in Slovenia. Influence of lithological properties is very significant, with the highest values of analysed variables observed in pure late-diagenetic intensely fractured Cordevolian dolomites, followed by Anisian and Late Triassic (‘Main’ dolomite) dolomites with high carbonate content and high primary porosity. The hydraulic parameters are not dependent on aquifer age, partial penetration, and well depth. The effects of depth to the water table and existence of low permeability overburden are not of major importance. The hydraulic parameter values are higher the closer to a river the wells are located, and topographic setting has a major effect. From the well reports, it was not always deduced whether the values of hydraulic conductivity and transmissivity stand for the values of the fractures or of the matrix, so it is proposed that when there is doubt as to whether these values are properly calculated, the most accurate parameters that can be used for a further prediction of aquifer yield are the specific capacity and, to a somewhat lesser extent, the specific capacity index.

Vertical electrical sounding (VES), pumping test and grain size distribution techniques have been used to model the hydraulic parameters in Ovwian, Nigeria. Twenty-two depth soundings were carried out with a maximum current electrode separation of 400 m to delineate the aquifer layers while the pumping test and grain size distribution procedures were conducted by drilling two boreholes where thirteen representative soil samples were collected at an interval of 3.048 m. The field data obtained from the resistivity sounding were modelled using the Win Resist software and the results when correlated with borehole log identified five geoelectric units made up of the topsoil, clayey sand, sandstone, fine grain sand and coarse grain sand. The sands of the third and fourth geologic layers constitute the aquiferous units with depth which varied between 6 and 42 m while the aquifer resistivity ranged between 100 and 2100 Ωm. The pumping test was analysed using the Copper Jacob method and the results revealed that the hydraulic conductivity and transmissivity of the aquifer from the reference well are 30.467 m/day and 495.072 m2/day, respectively. These results together with results from the vertical electrical soundings were used to model the hydraulic conductivity and transmissivity values for the area. This showed that the hydraulic conductivity of the area ranged from 28.595 to 38.435 m/day, with a mean value of 30.757 m/day while the transmissivity ranged from 185.697 to 1310.636 m2/day, with a mean of 495.752 m2/day. The grain size distribution analysis also revealed the hydraulic conductivity value of 1.46–171.94 m/day with an average of 38.880 m/day, while transmissivity ranged from 23.725 to 2794.025 m2/day with an average values of 631.738 m2/day. The close approximations of the results revealed the reliability of the VES, pumping test and grain size distribution analysis in the estimation of aquifer hydraulic parameters for groundwater resource development. Analyses of the results obtained in this study suggest that the aquifer is prolific and highly permeable with a high degree of rechargeability.

Estimation of hydraulic parameters is essential to understand the interaction between groundwater flow and seawater intrusion. Though several studies have addressed hydraulic parameter estimation, based on pumping tests as well as geophysical methods, not many studies have addressed the problem with clayey formations being present. In this study, a methodology is proposed to estimate anisotropic hydraulic conductivity and porosity values for the coastal aquifer with unconsolidated formations. For this purpose, the one‐dimensional resistivity of the aquifer and the groundwater conductivity data are used to estimate porosity at discrete points. The hydraulic conductivity values are estimated by its mutual dependence with porosity and petrophysical parameters. From these estimated values, the bilinear relationship between hydraulic conductivity and aquifer resistivity is established based on the clay content of the sampled formation. The methodology is applied on a coastal aquifer along with the coastal Karnataka, India, which has significant clayey formations embedded in unconsolidated rock. The estimation of hydraulic conductivity values from the established correlations has a correlation coefficient of 0.83 with pumping test data, indicating good reliability of the methodology. The established correlations also enable the estimation of horizontal hydraulic conductivity on two‐dimensional resistivity sections, which was not addressed by earlier studies. The inventive approach of using the established bilinear correlations at one‐dimensional to two‐dimensional resistivity sections is verified by the comparison method. The horizontal hydraulic conductivity agrees with previous findings from inverse modelling. Additionally, this study provides critical insights into the estimation of vertical hydraulic conductivity and an equation is formulated which relates vertical hydraulic conductivity with horizontal. Based on the approach presented, the anisotropic hydraulic conductivity of any type aquifer with embedded clayey formations can be estimated. The anisotropic hydraulic conductivity has the potential to be used as an important input to the groundwater models.

Transmissivity coefficient T and hydraulic conductivity K data presented in this paper were derived from specific capacity data on pumping tests from boreholes and wells, stored in the archive of the Geological Survey of Slovak Republic. These specific capacity data were treated by a re-interpretation process, eliminating influences of differently performed pumping tests and taking into account hydraulic resistivity both of wells and aquifers. Four typical hard-rock aquifer types were evaluated and compared: limestones, dolomites, granitoids and metamorphic rocks. Limestones and dolomites (outcropping in Slovakian West Carpathians) were all of Middle/Upper Triassic age, diagenetically consolidated into rigid masses and afterwards tectonically reworked to form densely fissured aquifers. Together 238 borehole tests were available for limestones, 463 for dolomites, 96 for granitoids and 91 for metamorphic rocks. Hydraulic parameters of all these rock types show log-normal statistical distribution and high heterogeneity. Therefore, geometric mean values of transmissivity and hydraulic conductivity were evaluated. Low hydraulic conductivity were found for both granitoids and metamorphic rocks (geometrical mean—G K —of 2.2 × 10−6 and 2.0 × 10−6 m∙s−1, and in one order of magnitude higher for limestones (1.1 × 10−5 m∙s−1). Aperture widening of fractures and joints in limestones by karstification—dissolution and mass transport—seem to be the reason for this. Surprisingly, the highest mean hydraulic conductivity value was found for dolomitic aquifers—2.4 × 10−5 m∙s−1. Also speleological evidence in the West Carpathians reveals that Middle/Upper Triassic dolomites here were not only diagenetically consolidated to rigid masses, afterwards tectonically disrupted into densely fissured aquifers, but also underwent a karstification process together with neighbouring limestones.

A study of the use of geoelectric sounding employing Schlumberger configuration in delineating aquifer(s) and estimation of hydraulic parameters has been carried out at Orerokpe, Western Niger Delta. Twenty (20) depth soundings were carried out with a maximum current electrode spacing of 400 m. The acquired depth sounding data were interpreted by partial curve matching and computer iterative techniques. The results identified four geologic layers which include; top soil, clay/sand, sandy clay/clayey/sand and sand. The sands of the third and fourth geologic layers constitute the aquifer, the depth to the aquifer varied between 6.4 m and 28.1 m with a mean depth of 17.5 m. The thickness of the aquifer varied between 15.1 m and 67.1 m with a mean thickness of 28.24 m. The hydraulic conductivity (K) value measured in a reference well was combined with electrical conductivity (σ) obtained from geoelectric sounding data, the resulting diagnostic relation (Kσ = constant) was combined with Dar-Zarrouk parameters to estimate the transmissivity and hydraulic conductivity values of the aquifer. The results indicated that the transmissivity values of the aquifer varied between 418.6 m/day and 1637.3 m/day while hydraulic conductivity values varied between 10.50 m/day and 45.71 m/day. The estimated parameters indicated that the aquifer in Original Research Article Aweto and Akpoborie; BJAST, 6(5): 486-496, 2015; Article no.BJAST.2015.104 487 seventy five (75) percent of the study area have high aquifer potential while the remaining twenty five (25) percent have moderate aquifer potential.

Groundwater exploration in basement terrain can be somewhat challenging. Aquifer parameters like hydraulic conductivity and transmissivity can help in predicting groundwater potential zones in basement terrains. The vertical electrical sounding investigation that involved the Schlumberger configuration was employed to map the subsurface layers within the crystalline basement of the Obudu Complex, southeastern Nigeria. Secondary electrical resistivity data (Dar Zarrouk parameters) and a few pumping test-derived hydraulic parameters (i.e., transmissivity and hydraulic conductivity) were employed to develop empirical models. These models were used to predict hydraulic parameters at locations where only geoelectrical parameters (i.e., aquifer layer thickness and electrical resistivity) exist. Results showed that the northeastern part of the study area and areas located within zones of major faults displayed relatively higher values of hydraulic conductivity and transmissivity. The study area was classified into good, moderate, and poor groundwater potential aquifer zones. This integrated approach can be adopted in other areas with similar geology, where pumping test information is scarce or limited, as an alternative means of predicting aquifer properties and delineating groundwater potential zones for sustainable development and management of groundwater resources.

Karlahi is largely underlain by granites and migmatites gneiss of the Adamawa Massif. The area lies west of Benue Trough and east of Cameroon volcanic line. The aim of this paper is to determine hydraulic properties of water bearing layer using parameters derived from Dar-Zarrouk equation and characterized them into groundwater potential zones. The resistivity values of the weathered and slightly weathered layers which make up the water bearing layers were added and an average was taken and used as the resistivity of the water bearing formation in computation of Dar-Zarrouk parameters in Karlahi area. The values of resistivity of water bearing formation ranged from 18 to 4963 Ωm with an average resistivity value of 549 Ωm and the thickness of the water bearing formation ranges from 21 to 32 m with an average thickness of 24.5 m. Conductivity values range from 0.000201 to 0.05509 (σ) while the longitudinal conductance range from 0.00483 to 1.2363 Ω-1, the transverse resistance ranges from 407 to 123504.3 Ωm2. The hydraulic conductivity and transmissivity values range from 0.14 to 25.87 m/day and 3.28 to 580.4 m2/day respectively. The longitudinal conductance values in Karlahi area revealed poor to good with an average longitudinal conductance value that is moderate. High transverse resistance values are located in the central and southern part of Karlahi area while low values are located in the eastern part. The spatial distribution map of transmissivity in the area revealed moderate to high transmissivity values in the north central part and a negligible to low transmissivity in southern part, extreme northeastern part. The groundwater potential map of Karlahi area shows negligible to weak potential groundwater zones in SW and SE, moderate potential in the central to northern part of Karlahi area.

Pore network modeling (PNM) with network extracted from 3D images is widely used for studying mass transport in porous media, with its accuracy heavily dependent on the precise determination of hydraulic and diffusive conductance values of local pore pairs. Deep learning (DL) prediction based on true pore geometry offers a promising approach for conductance estimation. However, due to arbitrarily orientation and the lack of explicit inlet and outlet surfaces in 3D extracted pore pair geometries, existing studies [24,25] have relied only on 2D cross section images for hydraulic conductance prediction. A custom finite difference method was recently developed, capable exclusively of estimating diffusion conductance from 3D pore geometry [26]. In this work, a convolutional neural network (CNN) was trained to estimate both diffusive and hydraulic conductance values, with reference ground truth values obtained by applying the Lattice Boltzmann Method (LBM) on 3D pore pair geometries. The predicted pore pair conductance values from the CNN closely matched the LBM results on unseen segmented image data. This study highlights the importance of using the full 3D pore pair geometry for accurate hydraulic conductance evaluation, rather than relying solely on 2D throat cross sections. To evaluate the generality of our method, we calculated the permeability and diffusivity of 3D porous media across a wide range of porosities using PNM with local conductance values predicted by our DL model. Comparisons with results of LBM indicate that while diffusivity was accurately predicted, permeability was underestimated. This underestimation is attributed to the over-segmentation of pore spaces, which resulted in an underestimated flow rate.

ABSTRACTThe estimation of hydraulic parameters is critical for the rational use of water resources and the development of reliable hydrogeological models. However, the cost of such estimation can be very high and the data are limited to the area near the pumping well. For this reason, complementary methods for estimating hydraulic conductivity and transmissivity have become increasingly important in recent years, such as the adjustment of empirical relationships between geoelectrical and hydraulic parameters. In this paper, two linear relationships were tested, combining resistivity measurements from well logging profiles and hydraulic conductivity values from pumping test data, in a semi‐confined fluvial aquifer in the province of Buenos Aires, Argentina. Furthermore, these relationships were used to obtain two‐dimensional (2D) hydraulic conductivity and transmissivity sections from electrical resistivity tomography using a high‐definition electrode array. Predicted values were compared with traditional pumping test in a near well showing very good agreement with both methods. Results showed that it would be possible to quantify the 2D variation of hydraulic parameters in aquifers and to identify high‐ or low‐productivity areas. By knowing this information in advance, it is possible to reduce the number of failures or unexpected results when drilling a well. These 2D sections also provide additional information about hydraulic parameters and their lateral variability, and can improve hydrogeological models without drilling new wells.

Estimation of hydraulic parameters in coastal aquifers is an important task in groundwater resource assessment and development. An attempt is made to estimate these parameters using geoelectrical data in combination with pore-water resistivity of existing wells. In the present study, 29 resistivity soundings were analysed along with 29 water samples, collected from the respective dug wells and boreholes, in order to compute hydraulic parameters like formation factor, porosity, hydraulic conductivity and transmissivity from coastal region of north Sindhudurg district, Maharashtra, India. The result shows some parts of the study area reveal relatively high value of hydraulic conductivity, porosity and transmissivity. Further, a negative correlation is seen between hydraulic conductivity and bulk resistivity. The hydraulic conductivity is found to vary between 0.014 and 293 m/day, and the transmissivity varied between 0.14 and 11,722 m2/day. The transmissivity values observed here are in good correspondence with those obtained from pumping test data of Central Ground Water Board. These zones also have high aquifer thickness and therefore characterize high potential within the water-bearing formation. A linear, positive relationship between transverse resistance and transmissivity is observed, suggesting increase in transverse resistance values indicate high transmissivity of aquifers. These relations will be extremely vital in characterization of aquifer system, especially from crystalline hard rock area.

A stochastic analysis of two‐dimensional steady state groundwater flow in a bounded domain is carried out by using Monte Carlo techniques. The flow domain is divided into a set of square blocks. A nearest‐neighbor stochastic process model is used to generate a multilateral spatial dependence between hydraulic conductivity values in the block system. Both statistically isotropic and statistically anisotropic autocorrelation functions are considered. This model leads to a realistic representation of the spatial variations in hydraulic conductivity in a discrete block medium. Results of the simulations provide estimates of the output distributions in hydraulic head. The probability distribution for hydraulic head must be interpreted in terms of the spatial variation of the expected head gradients, the standard deviation in the hydraulic conductivity distribution, the ratio of the integral scales of the autocorrelation function for conductivity to the distance between boundaries on the flow domain, and the arrangement of statistically homogeneous units within the flow domain. The standard deviation in hydraulic head increases with an increase in either the standard deviation in hydraulic conductivity or the strength of the correlation between neighboring conductivity values. The standard deviations in hydraulic head are approximately halved when a uniform, bounded, two‐dimensional flow field is reduced to one‐dimensional form. The uncertainties in the predicted hydraulic head values are strongly influenced by the presence of a spatial trend in the mean hydraulic conductivity. In evaluating the concept of an effective conductivity for a heterogeneous medium, both the nature of the spatial heterogeneities in hydraulic conductivity and the flow system operating within the flow domain must be considered.

The hydraulic characteristics of aquifers in Lokoja and Patti Formations were investigated using combination of vertical electrical sounding (VES), pumping and laboratory tests. A total of 20 VES (10 each in areas underlain by Lokoja and Patti Formations) were carried out at different locations with 5 pumping tests around VES stations in order to determine the geoelectric layers, thickness, depths to water table and groundwater potential of the area. 21 samples extracted fromaquiferous units of surface outcrops were also subjected to laboratory constant head and falling head permeameter tests in order to determine hydraulic conductivity (K) values using the Darcy’s law of liquid flow. The results of VES for areas underlain by Lokoja and Patti Formations revealed 4-5 geo-electrical layers. The depths to water table vary from 5.91-40.8 m. Thickness values are within the range of 7.37-27.3 m for aquiferous units of Lokoja Formation, and 10.8-20.1 m for the Patti Formation. The results of aquifer characteristics using Dar-Zarrouk Parameter gave hydraulic conductivity (K) values between 1.92-91.7 m/day and 2.15-31.8 m/day for aquifers of Lokoja and Patti Formations respectively. Transmissivity (T) values of the aquiferous units of Lokoja Formation fall within 24.97-2117 m2/day, while those of Patti Formation vary from 27.9-456.91 m2/day. There is a strong correlation between the values of measured and calculated hydraulic conductivity and transmissivity between measured and calculated transmissivity for the five wells (R2 = 0.99 and 0.92, respectively). Based on the results obtained and interpretations proffered, aquiferous units in both formations are capable of yielding optimum groundwater for private consumption and partly to small communities, and to some extent can supply water for great regional use. It is suggested that similar study should be carried out in other sedimentary basins where to aid regional planning and management of groundwater resource.