Aquifer Hydraulic Parameters Research Articles

Application of surface geophysical investigations and pumping test data analysis for better characterization of aquifer hydraulic parameters, Upper Awash Sub-Basin, Central Ethiopia

Study regionUpper Awash River Sub-basin in central Ethiopia Study focusThe research aimed to estimate aquifer parameters and conduct resistivity modeling in the study area. Data were collected from 890 Schlumberger Vertical Electrical Soundings (VES) points strategically distributed across six selected zones. The VES data were analyzed using computer modeling and curve-matching techniques to interpret the resistivity responses of the geological formations. This analysis provided insights into the subsurface characteristics and identified potential aquifer zones. New insights for the regionThe interpreted curves from the VES data and Root Mean Square (RMS%) values ranging from 0.36 % to 1.67 %, indicating a good fit between observed and modeled data. Resistivity modeling and geoelectrical sections were produced along specific lines, visualizing subsurface structures and confirming the resistivity responses of the geological formations. To determine aquifer parameters, the Dar-Zarrouk parameters were calculated from the interpreted curves, yielding crucial information about hydraulic properties such as hydraulic conductivity (K) and transmissivity (T). Hydraulic conductivity values ranged from 1.1 m/day to 21.7 m/day, while transmissivity values ranged from 144.3 m²/day to 2763.3 m²/day. Validation against borehole pumping test data showed strong correlations: R² = 0.9873 for transmissivity and transverse resistance, and R² = 0.9352 for hydraulic conductivity and resistivity. These findings enhance the understanding of the complex volcanic aquifer characteristics in the Upper Awash River Sub-basin, aiding sustainable groundwater management and development in the area.

Groundwater Characteristics’ Assessment for Productivity Planning in Al-Madinah Al-Munawarah Province, KSA

In recent times, drilling groundwater wells for irrigation, domestic, and industrial uses is increasing at a high rate in Saudi Arabia, meaning that groundwater is becoming a primary water resource. In the study region, over-exploitation and unsustainable performance severely deteriorate groundwater. Therefore, it is important to monitor the groundwater levels and quality as well as to detect the hydraulic parameters in order to plan and maintain groundwater sustainability. Knowledge of aquifer hydraulic parameters and groundwater quality is essential for the productivity planning of an aquifer. Therefore, this study carried out a thorough analysis on measured depth to groundwater data (2017 and 2022), borehole pumping test records, and chemical analysis of the collected water samples, especially in the presence of overexploitation and scarcity of recharge scale. To accomplish this aim, measurements of 113 groundwater wells (including 103 water samples) and analysis of 29 pumping tests between step and long-duration tests were made of all aquifer characteristics. These parameters consist of well loss, formation loss, well efficiency, specific capacity, transmissivity, hydraulic conductivity, resulted drawdown, and physiochemical parameters. Thematic maps were generated for all parameters using the geographic information system (GIS) and diagrams to strategize the groundwater productivity in Al-Madinah Al-Munawarah Province. The estimated hydraulic parameters are highly variable. Four distinct portions were identified for aquifer potentiality based on these varying ranges. Both the north and east of the region are good for groundwater productivity due to good aquifer materials, whereas the southwestern and western portions have relatively poor values. The analyzed groundwater was categorized as fresh to slightly salty water, with two primary chemical types identified showing a prevalence of mixed NaCl and Ca-Mg-SO4/Cl water. Finally, groundwater productivity assessment predicts that the aquifers can support the Al-Madinah Al-Munawarah Province demand for several years if certain well distributions are adopted and for a few hours/day of pumping rate. The maps that have been created can be examined to aid in making decisions related to hydrology.

Semi-Analytical Modeling of Transient Stream Drawdown and Depletion in Response to Aquifer Pumping.

Analytical and semi-analytical models for stream depletion with transient stream stage drawdown induced by groundwater pumping are developed to address a deficiency in existing models, namely, the use of a fixed stream stage condition at the stream-aquifer interface. Field data are presented to demonstrate that stream stage drawdown does indeed occur in response to groundwater pumping near aquifer-connected streams. A model that predicts stream depletion with transient stream drawdown is developed based on stream channel mass conservation and finite stream channel storage. The resulting models are shown to reduce to existing fixed-stage models in the limit as stream channel storage becomes infinitely large, and to the confined aquifer flow with a no-flow boundary at the streambed in the limit as stream storage becomes vanishingly small. The model is applied to field measurements of aquifer and stream drawdown, giving estimates of aquifer hydraulic parameters, streambed conductance, and a measure of stream channel storage. The results of the modeling and data analysis presented herein have implications for sustainable groundwater management.

Using the Periodic Dynamics of Well Water Levels to Estimate Time Series Changes in Aquifer Parameters

Due to the long duration and high cost of traditional pumping tests, the response of well water levels to seismic waves, earth tides, and barometric pressure provides a feasible method for determining continuous changes in aquifer hydraulic parameters. Aimed at the problem that the response phase shift of well BB water levels to tide M2 is greater than that of tide O1, this paper preferentially calculated the time series changes in S, Be, n, and BKu based on the response mechanism of well water levels to barometric pressure and earth tides with the help of the smooth moving method. Then, by using the mixed flow model, the variation in the transmissivity and leakage coefficient over time was simultaneously obtained, and the evolution process and characteristics of aquifer parameters near well BB caused by the Wenchuan earthquake are ultimately discussed. The calculation results are basically consistent with the previous pumping test, and have been verified and compared by using other scholars’ methods. This solving process avoids problems such as excessive dependence on initial values, multiple solutions, and unstable tide O1, which has a promoting effect on the study of the impact of seismic activity on aquifer systems.

Utilizing of aquifer hydraulic parameters to assess the groundwater sustainability in the new reclamation area of Moghra Oasis: Western Desert—Egypt

The sustainability of groundwater aquifers requires evaluating several parameters, the most important of which are hydraulic parameters. Therefore, the essential aim of this research is to develop a management plan for the Moghra aquifer in order to prevent the expanding of water level decline and degradation of groundwater quality due to overexploitation and scarcity of recharge. To achieve this goal, all aquifer hydraulic parameters such as transmissivity, hydraulic conductivity, radius of interference, specific capacity, resulted drawdown, well loss, formation loss, well efficiency, and optimum safe yield had been measured for 40 groundwater wells drilled in the new reclaimed areas of Moghra Oasis. Based on geographic information system (GIS), hydrogeological cross sections and thematic maps for all parameters were created such as aquifer thickness, water table, groundwater flow direction, drawdown and groundwater salinity maps. The results revealed that clay and shale beds separated the three water-bearing formations of the Moghra aquifer. The aquifer-saturated thickness ranged from 30 and 102 m, and the groundwater level was below the mean sea level for all wells (ranges from − 72 to − 26.6 m). The calculated hydraulic parameters based on the analysis of long-duration pumping tests indicated that the studied aquifer has a wide variety of transmissivity (T) between 631 and 3768 m2/day, hydraulic conductivity (K) between 13.4 and 104.6 m/day, radius of influence from 126.3 to 581.3 m and specific capacity between 377.14 and 883.72 m2/day. On the other hand, the evaluation of existing drilled wells performance based on the results of step tests showed that well loss coefficient ranges between 0.0004749 and 0.0676 (h2/m5), formation loss coefficient varies from 3.34 × 10–8 to 4.80 × 10–6 (h/m2), well efficiency (γ) ranged from 50.53 to 98.08%, and optimum safe yield ranged from 40 to 98 (m3/h). Results of aquifer mapping and pumping tests can be more important for solving water scarcity issues, non-polluting water issues, health issues, and source of fresh water on the surface of the earth. The characterization of aquifer parameters in the study area, however, should be a significant component in the scientific planning and sustainability of groundwater.

Evaluation of aquifer parameters through integrated approach of geophysical investigations, pumping test analysis and Dar-Zarrouk parameters in the central part of Bari Doab, Punjab, Pakistan.

In the central part of Bari Doab in Punjab Province of Pakistan, the factors such as sporadic rainfall pattern, decrement of water in rivers, subsurface salinity and excessive mining of groundwater have badly affected the hydrogeology and recharge system of aquifer. The present research work is an endeavour to evaluate the characteristics and potential of aquifer for its future sustainable availability within the study area of central part of Bari Doab. The geophysical studies, pumping tests data, borehole logs and Dar-Zarrouk parameters were used integrally to evaluate the aquifer hydraulic and hydrologic parameters in the study area. VES technique of geophysical investigations using Schlumberger electrodes configuration was carried out at sparsely distributed 435 locations. Litho-logs and VES results altogether decipher that the subsurface alluvial succession is primarily composed of intermixed layers of sand, gravel, clay, silt and some kankar inclusions. The VES data allied with pumping test analysis of test wells in the study area were used to evaluate the aquifer hydraulic properties. Comparatively low values of discharge rate, hydraulic conductivity and transmissivity were evaluated in two wells whilst relatively higher values of these parameters were evaluated in rest of six wells. The results of hydrologic parameters also confirm the results of hydraulic parameters in the wells. Finally, the Dar-Zarrouk parameters were used for the estimation of hydraulic parameters for whole study area and the aquifer zones of relatively high and low potential were delineated.

Evaluation of geophysical parameters for groundwater productivity in the Commune of Jesse, Delta State Nigeria


 Aquifer geohydraulic properties in Jesse were studied by the application of vertical electrical sounding (VES) and pumping test. The VES data was collected using ABEM SAS 1000 Terrameter and results processed using manual matching of curves and computer iteration, and interpreted in the forms of geologic models and geoelectric layers. The aquiferous unit was found at a depth of 5.30 m to 30.30 m with a range of resistivity from 87.30 Ω-m to 1945.40 Ω-m. Dar-Zarrouk parameters estimation and results of borehole pumping test produced the aquifer hydraulic parameters. The hydraulic conductivity values range from8.171 - 8.279 m/day, transmissivity from 43.8770 - 517.7480 m2/day, and formation factor from 0.369 - 8.501. These results are indications of a prolific and high yielding aquifer capable of withstanding long duration of pumping. Results of groundwater electrical conductivity and total dissolved solids ranged from 11.65 - 198.80 μs/cm, and 29.40 - 35.40 mg/dm3 respectively, signifying very moderate mineralization of the groundwater. The average electrical conductivity of 68.04 μS /cm and total dissolved solids of 32.58 mg/L were lesser than the acceptable limits of the Nigerian Standard for Drinking Water Quality (NSDWQ) of 1000 μS/cm and 500 mg/L respectively. This study affirmed that the aquifer in Jesse is suitable for groundwater exploitation for local and regional purposes.

Effect of injection water ionic strength on estimating hydraulic parameters in a 3D sand tank using silica encapsulated magnetic DNA particles

We investigated the applicability of Silica encapsulated, superparamagnetic DNA particles (SiDNAmag) in determining aquifer hydraulic parameters at different ionic strengths (1 mM, 5 mM, and 20 mM phosphate buffer) of injection suspension. Thereto, in a homogeneous, unconsolidated sand tank we pulse - injected two uniquely sequenced SiDNAmag at two injection points. At 0.5 m and 0.8 m downstream from the injection points, we measured the concentration of SiDNAmags at three vertically distributed and two horizontally distributed sampling locations. We estimated the hydraulic parameter distributions from the SiDNAmag breakthrough curves through a Monte – Carlo approach and compared the parameter distributions with salt tracer breakthrough curves. Our results indicated that at all the ionic strengths, the times of peak concentrations, and the shapes of the breakthrough curves were similar to the salt tracer. As compared to the salt, a 1 – 3 log units reduction in the maximum effluent concentration of SiDNAmag was due to kinetic attachment. The attachment rate reduced from 1 mM to 5 mM phosphate buffer possibly due to competitive adsorption of phosphate onto the favourable attachment sites. SiDNAmag attachment rate further increased in 20 mM buffer suspension, possibly due to the compression of electric double layer and reduction in energy barrier for attachment. The parameter distributions of hydraulic conductivity (k), effective porosity (ne), longitudinal dispersivity (αL), vertical transverse dispersivity (αTV /αL) and horizontal transverse dispersivity (αTH /αL) estimated from the SiDNAmag and the salt tracer breakthrough curves were statistically similar. Our work contributes to the applicability of colloidal SiDNAmags for determining hydraulic parameters at different ionic strength conditions.

Estimation of aquifer hydraulic parameters using electrical resistivity method: A case study for Damaturu, Northeast Nigeria.

In this study we estimated the aquifer hydraulic parameters of Damaturu, Yobe State, Nigeria, using electrical resistivity method. Schlumberger configuration was adopted for the study. Five geologic layers, which are the Topsoil, Clay, Sand, Sandy-clay, and Sand were delineated in the study area. The results of the measured aquifer parameters revealed that the aquifer resistivity values in the study area ranged from 126 to 518 Ωm and the aquifer has an average resistivity of 328 Ωm. The aquifer thickness ranged from 39 to 71m with an average value of 59 m. The aquifer has hydraulic conductivity values which ranged from 1.138 to 4.231 m/day with an average value of 1.915 m/day. The transmissivity of the aquifer ranged from 62.7 to194.64 m2 /day with an average transmissivity of 111 m2 /day. The porosity of the aquifer ranged from 30.13 to 31.44 % with an average value of 30.6 %. The porosity values showed that the study area has an appreciable porosity for effective groundwater flow and storage. The results of the measured aquifer parameters also revealed that the study area has good groundwater potential. Therefore, the results of this study will assist in providing exquisite information for groundwater exploration, abstraction, development and pollution control in the study area.

Aquifer characterization using geophysical and pumping test data in Kericho, Kenya

The exploration of groundwater resources has considerable potential for boosting water supplies in Kericho County, Kenya. However, it is underused due to limited knowledge caused by lack of adequate research in this field. As a way to fill this gap, this study aimed to characterize hydraulic and hydrogeological parameters controlling groundwater occurrence in the Kericho aquifer in Kericho County, Kenya. To achieve this objective, the study utilized a combination of geophysical and pumping test data. Consequently, fifty Vertical Electric Soundings (VES) were carried out to determine the aquifer properties of the study area. Further, seven out of fifty surveyed sites were drilled to depths ranging between 30m and 230m, and test pumping was done for 24 hours. Geophysical results show that the average hydraulic conductivity in the study area varies from 1.96 m day-1 to 6.2 m day-1 . The transmissivity ranged from 35.83 m2 day-1 to 5166.4 m2 day-1 , while the yield ranged between 0.7 and 9.7 M3 /hr. The aquifer hydraulic parameters determined from geophysical and pumping test data were analysed using one-way analysis of variance (ANOVA). The results show no significant difference (p = 0.948151> 0.05) on hydraulic conductivity between geophysical and pumping test methods. Therefore, this study confirmed the reliability of both methodologies for groundwater assessment. Identifying prospective groundwater zones in the research area demonstrates that the combination of these methods is efficient and suited for groundwater exploration. It is suggested that observation wells be added in future studies to allow for the computation of storativity.

Estimating Hydraulic Parameters of Aquifers Using Type Curve Analysis of Pumping Tests with Piecewise-Constant Rates

Aquifer hydraulic parameters play a critical role in investigating various groundwater hydrology problems (e.g., groundwater depletion and groundwater transport), and the Theis formula for constant-rate pumping tests is commonly used to estimate them. However, the pumping rate in the field usually varies with time due to some factors, making the classical constant-rate model unsuitable for accurate parameter estimation. To address this issue, we developed a novel dimensionless-form analytical solution for variable-rate pumping tests involving piecewise-constant approximations for variable pumping rates. Analysis of the time–drawdown curves revealed that the first-step type curve was consistent with the Theis curve. However, the curves of subsequent steps deviated from the Theis curve and were associated with the first dimensionless inflection time (t1,D), which depended on the hydraulic conductivity (K) and specific storage (Ss) of the confined aquifers. On this basis, a new type curve method for estimating the aquifer K and Ss was proposed by matching the observed drawdown data with a series of type curves dependent on t1,D. Furthermore, this method can handle recovery drawdown data. We applied this method to a field site in Wuxi City, Jiangsu Province, China, by analyzing the drawdown data from four pumping tests. The hydraulic parameters estimated using this method were in close agreement with those calibrated via PEST. The calibrated K values were further validated by comparing them with lithology-based results. In summary, the geometric means of K and Ss were 6.62 m/d and 3.16 × 10−5 m−1 for the first confined aquifer and 0.92 m/d and 2.34 × 10−4 m−1 for the second confined aquifer.

Impact of high‐permeability preferential flow zones on pumping‐induced airflow in unconfined aquifer

AbstractWhen the unsaturated zone of the unconfined aquifer is covered by a low‐permeability upper layer, significant airflow will be generated in the unsaturated zone during water pumping. However, high permeability preferential flow zones (PFZs) such as fractures and macropores are frequently present in the unsaturated zone, forming the preferential fluid flow paths, which may change the original airflow pattern in the unsaturated zone during the pumping test and consequently affect the precision of obtained aquifer hydraulic parameters. The main objective of this paper is to investigate the effect of PFZs in low‐permeability upper layer on pumping‐induced airflow in the unsaturated zone by numerical simulations of transient three‐dimensional air‐water two‐phase flow and to quantify errors in the aquifer hydraulic parameters obtained during pumping test. The results demonstrate that a large amount of air flows quickly from the atmosphere into the unsaturated zone through the PFZs, and that the PFZs can draw some air from the nearby low‐permeability soils as well. The significant influx of air through PFZs also reduces the negative air pressure in the unsaturated zone and decreases the drawdown in the saturated zone at intermediate times, which are nevertheless still greater than the results obtained in the homogeneous aquifer. Estimations of the aquifer hydraulic parameters reveal that errors of these parameters obtained are smaller when the PFZs with favourable combinations of permeability, width and quantities facilitate more air to flow into the unsaturated zone.

Exploring hydrogeological parameters by integration of geophysical and hydrogeological methods in northern Khartoum state, Sudan

The recent study aims to detect the spatial distribution of the hydraulic parameters and evaluate the protective capacity of the groundwater aquifers in northern Khartoum state using geophysical and hydrogeological methods. The study area is located in the transition zone between the sedimentary basin and the area dominated by crystalline basement rocks. Vertical electrical sounding (VES) measurements, using Schlumberger configuration, were taken along three profiles to delineate the thicknesses of the sediments and groundwater aquifers. The VES measurements were combined with the lithology logs to reduce the uncertainty of the resulting models. VES findings denoted that the study area comprises two hydraulically connected aquifers. The upper aquifer is composed of fine sandstone with an average thickness of 50 m, and the lower aquifer has a thickness of up to 150 m. These two aquifers are confined to semi-confined, separated by relatively thick aquitards. To evaluate the aquifer quantitively, pumping test analysis using Cooper-Jacob method was applied to estimate the aquifer's hydraulic parameters, including transmissivity and hydraulic conductivity. The pumping test approach is costly and time-consuming, and extrapolation of the results is restricted to homogeneous boundary conditions. Since groundwater aquifers are mostly heterogeneous, a geophysical-based method called Dar Zarrouk parameters was applied to give a continuous estimate for the hydraulic parameters. Dar Zarrouk parameters include longitudinal conductance and transverse resistance, combining the true resistivity and thickness obtained from the inverted VES data to determine the hydraulic parameters. The calculated hydraulic parameters from the pumping test and Dar Zarrouk parameters showed high compatibility. Furthermore, longitudinal conductance was used to predict the protective capacity of the aquifers. Generally, it ranged from good to very good protective capacity suggesting potable water quality. The findings of this research indicated that the groundwater aquifer in the study area is ideal for groundwater exploitation. However, this study recommends applying a detailed geophysical survey to reduce the uncertainty of the resulting geological and hydrogeological models.

Time- and frequency-domain determination of aquifer hydraulic properties using water-level responses to natural perturbations: A case study of the Rongchang Well, Chongqing, southwestern China

Effective management of groundwater resources requires accurate estimates of aquifer hydraulic parameters. One approach for estimating these parameters is to use aquifer water-level responses to natural perturbations, such as barometric pressure and earth tides. In this study, the time- and frequency-domain methods of barometric pressure and earth tide response are used to estimate aquifer hydraulic properties (transmissivity and specific storage), and taking the Rongchang well in Southwest China as an example in application. The results show that the specific storage and transmissivity estimated by the four different methods vary widely, with specific storage ranging from 8.43×10−7 − 4.68×10−5/m and transmissivity ranging from 6.90×10−7 − 3.40×10−6 m2/s. However, the differences in aquifer transmissivity are smaller than the aquifer specific storage. The transmissivity obtained by the slug test is one order lager than those from Barometric (frequency), Barometric (time) and Tidal-Turnadge methods, and two orders of magnitude greater than those of Tidal-Merrit method. The Ss value obtained by the Barometric (time) method is closer to the results of the slug test, while the Ss values obtained by the other three methods are one or two orders of magnitude smaller than the slug test results. In the Tidal-Turnadge method, the uncertainty in the effective porosity introduces an additional uncertainty in the results. The errors in the calculation process are minor in comparing to the uncertainties caused by the model assumptions. For the Rongchang well, the tidal response method averages the hydraulic properties on a larger area than that of CBP model.

Potential aquifer mapping for cost-effective groundwater reverse osmosis desalination in arid regions using integration of hydrochemistry, environmental isotopes and GIS techniques

In arid regions, water resources are scarce; therefore, sea and brackish groundwater desalination using reverse osmosis (RO) techniques is commonly used to provide freshwater for potable purposes. El-Moghra Oasis, a case study of an inland depression, represents an arid region in the Western Desert of Egypt. The oasis relies mainly on the brackish groundwater in El-Moghra Aquifer for salt-tolerant crop irrigation and feeding desalination plants. The RO brackish groundwater desalination conserves about 75% of the total cost compared to seawater as feed water. Accordingly, the main target of the present work is to allocate cost-effective sites for constructing desalination plants to solve freshwater shortages. The hydrogeochemical and isotopic techniques have been applied to understand the aquifer recharge mechanism and the main factors that deteriorate the groundwater quality. Additionally, an Analytical Hierarchy Process (AHP) relying on the geographic information systems (GIS) utilized to delineate the promising desalination sites. Four main criteria linked with the cost of RO groundwater desalination were investigated, including aquifer hydraulic parameters, hydrogeochemical characteristics, recharge indicators based on isotopic tracers, and other miscellaneous parameters related to the site accessibility and environmental issues. These four main criteria include fourteen sub-criteria; depth to water (DTW), aquifer saturated thickness (ST), transmissivity (T), total dissolved solids (TDS), iron (Fe), total groundwater hardness (TH), calcium sulfate (CaSO4), silica (SiO2), strontium (Sr), oxygen-18 (δ18O), global solar radiation (GSR), land slope (LS) and distance to roads (D). The final suitability map identifies the most favorable locations for constructing a desalination plant is in the northeast, which comprises 64.5% of the study area. The locations with low appropriateness are concentrated in the west and southwest and account for 35.5% of the area.

Determination of Aquifer Hydraulic Characteristics from Surface Electrical and Borehole Measurements in Ozoro, Nigeria

Surface electrical and borehole measurements were undertaken in order to establish the hydraulic characteristics of alluvial aquifer in Ozoro, Delta State. Ten vertical electrical sounding data were acquired using Schlumberger Configuration. Borehole measurements which included pumping test, well logging and the distribution of grain size analysis were also carried out. The results of the electrical sounding indicate that the aquiferous layer is located between the fourth and fifth layers with resistivity ranged from 53.5 Ωm - 1279 Ωm. The aquifer thickness ranged from 7.67 m - 49.4 m and transmissivity values ranged from 41.4 - 330.5 𝑚2/day. The average hydraulic conductivity (k) value obtained is 6.2 m/day. The borehole lithology, resistivity and spontaneous potential log indicate the subsurface lithology to consists of top soil (brownish), clayey sand, clay, fine sand and gravelly sand. The Cooper Jacob solution was used in the analysis of the borehole pumping experiment and the obtained hydraulic conductivity, transmissivity, storativity and specific capacity are 6.8 m/day, 0.067 m2/min (96.48 𝑚2/day), 25.47 and 0.364 m2/min (524.6 m2/day) respectively. Also, the grain size distribution analysis using the Hazen approximation gave hydraulic conductivity as 11.55 m/day. The results showed that all three methods are applicable for determining aquifer hydraulic parameters.

Evaluation of aquifer hydraulic conductivity and transmissivity of Ezza/Ikwo area, Southeastern Nigeria, using pumping test and surficial resistivity techniques.

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.

Hydromechanical characterization of tide-induced head fluctuations in coastal aquifers: The role of delayed yield and minor permeable layers

Tidal analysis is an aquifer scale testing that is a low-cost alternative to pumping tests for evaluating aquifer hydraulic parameters without groundwater extraction. Many analytical solutions may be used to assess aquifer head fluctuations in response to tidal fluctuations. Nonetheless, they are rarely used in practice. Aside from that, most analytical solutions are based on a conceptual model that typically consists of an unconfined aquifer and a confined aquifer separated by an aquitard, where hydraulic head fluctuations in the unconfined aquifer part are commonly neglected. Additionally, the frequent confined aquifer short response time to sea-level fluctuations cannot rely on hydraulic connection of the confined aquifer to the sea through the aquitard. As a consequence, when analytical solutions are applied to real-world cases, the hydraulic diffusivity is overestimated. In this study, we investigate through different numerical simulations the fluctuations of the phreatic surface by considering the delayed yield. Numerical results demonstrate that the mechanical effect generated by the load over the sea bottom exerted by sea-level fluctuations is a key factor when determining aquifer parameters. We further show that in multilayer systems, head fluctuations in various aquifer layers can cause interferences and, consequently, increased attenuation of the tidal signal, resulting in an overestimation of the inferred hydraulic diffusivity. Our results provide guidance on how to properly reproduce tidal responses in coastal aquifers.

Pumping test analysis for assessment of hydraulic parameters and aquifer system formation in hilly terrain

Abstract Groundwater conditions (GWCs) of an area depends on aquifer hydraulic parameters such as storativity () or storage coefficient (), transmissivity () and hydraulic conductivity (). It plays a key role concerning groundwater flow modeling, well performance, solute and contaminant transport assessment and also for identification of areas for additional hydrologic testing. Specifically, the geologic formation of a region controls the porosity and permeability; however, in hilly terrain prospecting ground water potential is more challenging due to its limited extent and its occurrences that are usually confined to fractures and weathered rocks. The present study aims at estimating the hydraulic parameters through pumping test analysis to assess aquifer system formation on hilly terrain from 16 bore wells. The aforesaid parameters were examined through a case study in some selective regions of Hamirpur district of Himachal Pradesh, India. The study area is controlled under two main geological horizons that is the post-tertiary and tertiary. The papers end with comparative results of hydraulic parameters and the aquifer systems formation on different GWCs, which may be helpful in the outlook of sustainable groundwater resource in the regions.

Discharge variation of multiple springs associated with a fractured aquifer

Springs are important source of fresh water for many regions of the world. Most mathematical models simulating spring discharge are linear and non-linear reservoir-based models that are simple and easy to use. They, however, suffer from oversimplification and a lack of physical processes that limit their applicability. The goal of this work is to present process-based analytical model of discharge variation of multiple springs associated with a rectangular fractured aquifer subjected to arbitrary recharge. The solution is obtained via Laplace and Fourier transformations along with the superposition principle and image well method for a constant flux point sink. Then the constant head point sink solution representing a single spring is obtained from the constant flux point sink solution. Finally, the constant head point sink solution is extended to simulate the multiple constant head sinks (or springs) utilizing the principle of superposition and matrix solution. The solution considers the vertical anisotropy of fractures, the inter-porosity flow between fractures and matrix blocks and the instantaneous gravity drainage of the water table. The results of this study are presented in the form of dimensionless discharge-time curve and dimensionless spring depletion volume-time curves. The influences of aquifer geometric and hydraulic parameters on spring discharge variation are explored. The presented model can be utilized to simulate the discharge variation of multiple springs depleting a fractured aquifer, to estimate the hydraulic parameters of the aquifer utilizing the discharge data of springs, and to evaluate the dynamic storage volume of multiple springs depleting a fractured aquifer, among other applications.