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Borehole geophysical logging of four production wells completed in Precambrian metagranite in Fauquier County, Virginia (USA), was conducted to characterize stratigraphy, collect water-bearing fracture orientations and describe vertical hydraulic gradients in the vicinity of each borehole. Long-term (48–90 h) single-well pump test data were reevaluated for each well to better characterize this locally important aquifer system. Single-well aquifer test analyses indicate mid-to-late-time infinite acting radial flow conditions within the fractured rock aquifer, followed by increasing late-time contribution of stored groundwater from recharge boundaries. Later-time pump test results are believed to indicate that water-bearing fractures within the metagranite are ultimately recharged by groundwater stored within the regolith. Assumptions about the presence of a recharge boundary sourced by the regolith were tested with a simple groundwater flow model that was calibrated to observed drawdown data associated with one of the long-term pump tests. This study identifies fracturing associated with shear-related metamorphic fabrics in the wellbore and demonstrates the significance of these fractures as mechanisms for accessing groundwater. Results from this investigation indicate that shear-related metamorphic fabrics can be important structures for integrating transmissive fracture networks within the Marshall Metagranite and possibly within other Blue Ridge basement rocks possessing similar metamorphic history.

Sustained pumping of groundwater can lead to declining water levels in wellfields and concerns regarding the sustainability of groundwater resources. Aquifer Storage and Recovery (ASR) is a promising approach for maintaining water levels in wells and increasing the sustainability of groundwater resources. Herein, an analytical model relying on superposition of the Theis equation is used to resolve water levels at 40 wells in three vertically stacked ASR wellfields operating in the Denver Basin Aquifers, Colorado (USA). Fifteen years of dynamic recovery/recharge data are used to estimate aquifer and well properties, which are then used to predict water levels at individual wells. Close agreement between modeled and observed water levels supports the validity of the analytical model for ASR wellfield applications. During the study period, 45 million m3 of groundwater is produced and 11 million m3 is recharged, leading to a net withdrawal of 34 million m3 of groundwater. To quantify the benefits of recharge, the analytical model is applied to predict water levels at wells absent the historical recharge. Results indicate that during recovery and no-flow periods, recharge has increased water levels at wells up to 60 m compared to the no-recharge scenario. On average, the recharge increased water levels during the study period by 3, 4, and 11 m for wells in the Denver, Arapahoe, and Laramie Fox-Hills Aquifers, respectively. This study demonstrates the utility of analytical modeling to quantify the effects of long-term ASR at wells.

The complex nature of the Ethiopian aquifer requires detail, characterization, and analysis. Consequently, characterization of groundwater flow and major aquifer systems was conducted in the upper left bank of the Jemma River catchment in the Blue Nile Basin. The research area covered 1255 km2. The main objective of the research was to characterize the aquifer systems and groundwater flow dynamics of the area. The software applied during the research work were aquifer test, ArcMap 10.2, global mapper 17, AutoCAD, Exelis ENVI, geomatics, and rockworks. Pumping test data and spring discharge together with qualitative field description were used to classify the aquifer system. Accordingly, the different aquifer classes are fissured aquifer developed on basalts on the plateau (moderate to low groundwater potential), mixed aquifer (high permeability and very high productivity), fissured aquifer developed on basalts in the valleys (high permeability and low to moderate storage), porous and fissured sandstone aquifer in deep valleys, and localized aquifer with intergranular porosity and permeability (high permeability and high productivity). From the analysis of water level measurements of boreholes, hand-dug wells, and springs, the groundwater flow system is controlled by surface morphology and lineaments. Therefore, the groundwater flows from SE and S-SSE corner towards the N and NW corner of the catchment. Understanding groundwater dynamics and characterizing the aquifer in the catchment are very crucial which in turn help to manage the available water resource for domestic, industrial, and agricultural purpose. Besides, the research will be used to manage aquifers from depletion.

This study offers a reinterpretation of archive aquifer tests, predominantly on the basis of recovery data, from an original datasheet of thermal water wells located in carbonate and sandstone aquifer units in the vicinity of Budapest, Hungary. The study compares the hydraulic conductivity (K) and specific storage (Ss) values derived in the first instance from an aquifer test evaluation. This included an initial application of the classical analytical Cooper and Jacob method. Subsequently, the visual two-zone (VTZ) numerical method was applied, then third, a more complex model, namely, WT software. It was found that the simple analytical solution is not able to represent the field conditions accurately, while in the course of the application of the VTZ model, it proved possible to alter the various hydraulic parameters within reasonable limits to fit the field data. In the case of the VTZ model, the researcher is required to calculate the accuracy of the fitted model separately, while with the WT model, this is automatic, the software seeks out the best fit. In addition to VTZ parameters, the WT model can efficiently incorporate data on up to 500 model layers, water level, and pressure. The optimization of the parameters may be achieved by automatic calibration, improving the accuracy of the numerical results. Recovery tests for 12 wells were numerically simulated to obtain values for vertical and horizontal hydraulic conductivity and specific storage for Triassic and Eocene fractured carbonate and the Upper-Miocene-Pliocene granular sandstone aquifer units. When an analytical solution is applied, only average values could be obtained. The conclusion reached was that the results of the analytical solution can be improved by the use of numerical methods. These methods are able to incorporate basic information on well design, aquifer material and the hydrogeological environment in the course of the evaluation. The revision of the archive recovery data using numerical methods may assist in the quest for better data for numerical flow and transport simulations without the need to perform new tests. In addition, the methods employed here can explain cases in which the original analytical interpretations proved unable to yield reliable data and predictions.

The Theis solution is perhaps the most influential and frequently used analytical model in groundwater hydrology. Its publication in 1935 led to immediate and continued use for simulating hydraulic head drawdown, in both confined and unconfined aquifers, as a tool in aquifer parameter estimation. For educational purposes, the Theis solution and the related Jacob’s approximation often serve as the backbone for teaching pumping-well theory, including topics such as boundary conditions in aquifers, image well theory, linear superposition, and pumping-induced streamflow depletion. Clearly, a thorough understanding of the Theis solution is critical for groundwater engineers and hydrologists. However, the solution often is presented as a “black box”, neglecting the actual origins of its derivation and accompanying physical context. This can lead to misconceptions about the model and its inherent limitations. In this paper, a physically based detailed derivation of the Theis solution is presented, along with a method of calculating drawdown from a pumping well without resorting to the final Theis equation. Examples of both constant-rate pumping and variable-rate pumping are presented and compared to results using the original Theis solution. In particular, variable pumping rates are accounted for by direct numerical integration of an earlier form in the original Theis derivation, removing the need for linear superposition of solutions in time. In this way, it is hoped the paper will provide a method of calculation that ties the model user to the physical meaning of the solution, including its assumptions.

Groundwater fluctuation usually reflects the property of aquifer in nature. Actually, water level change can be caused not only by barometric pressure changes resulted from atmospheric motion, but also by the tidal effect from nearby marine system or water body. In confined aquifer, an increase in barometric pressure usually will cause a decrease in water level in well to an amount described by the barometric efficiency. The barometric efficiency can be also used as a correction factor to remove barometric effects on water levels in wells during an aquifer test. With the rise of the tidal sea on the coastal aquifer, it indicates that there will be compensating increases of water pressure and stress in the skeleton of aquifer. External forcing on groundwater level in the coastal aquifer, such as barometric effect and tidal sea, usually affect the water level to fluctuate with different phases to some extent. An adaptive adjustment to remove the combination of barometric and oceanic tidal efficiency is presented in this study. This research suggests that the presented formula can simultaneously identify the individual efficiency for barometric effect and load of tidal sea considering their combined observation of groundwater level in aquifer system. An innovative application has been demonstrated for the deep aquifers adjacent to the West Pacific Ocean.

A phased multi-disciplinary approach was used to investigate potential environmental impact on the overburden aquifer and karst (bedrock) aquifer from the historic use of a suspected fire training pit at the former Marietta Air Force Station in Lancaster County, Pennsylvania. Investigation techniques have included direct push technology, real-time sample analysis via use of a mobile laboratory, earth resistivity imaging/induced polarization, geophysical borehole logging, packer testing, installation of one multi-port well with five sampling ports set in the karst aquifer, installation of multiple conventional monitoring wells, and completion of multiple rounds of groundwater sampling and data analysis. Both the vertical and lateral extents of groundwater contamination by chlorinated volatile organic compounds were delineated in the overburden and karst aquifer. The pathway-focused human health risk assessment has indicated that groundwater remediation is required to meet the federal and state health standards for volatile organic compounds. Based on the hydrogeological conditions and the nature and extent of the delineated contamination, plumes in both the overburden and karst aquifers, chemical oxidation (in the karst aquifer), and enhanced bioremediation (in the overburden aquifer) have been selected as the preferred alternatives for groundwater remediation, with monitored natural attenuation included as a common component of both alternatives.

Process-based groundwater models are useful to understand complex aquifer systems and make predictions about their response to hydrological changes. A conceptual model for evaluating responses to environmental changes is presented, considering the hydrogeologic framework, flow processes, aquifer hydraulic properties, boundary conditions, and sources and sinks of the groundwater system. Based on this conceptual model, a quasi-three-dimensional transient groundwater flow model was designed using MODFLOW to simulate the groundwater system of Mahanadi River delta, eastern India. The model was constructed in the context of an upper unconfined aquifer and lower confined aquifer, separated by an aquitard. Hydraulic heads of 13 shallow wells and 11 deep wells were used to calibrate transient groundwater conditions during 1997–2006, followed by validation (2007–2011). The aquifer and aquitard hydraulic properties were obtained by pumping tests and were calibrated along with the rainfall recharge. The statistical and graphical performance indicators suggested a reasonably good simulation of groundwater flow over the study area. Sensitivity analysis revealed that groundwater level is most sensitive to the hydraulic conductivities of both the aquifers, followed by vertical hydraulic conductivity of the confining layer. The calibrated model was then employed to explore groundwater-flow dynamics in response to changes in pumping and recharge conditions. The simulation results indicate that pumping has a substantial effect on the confined aquifer flow regime as compared to the unconfined aquifer. The results and insights from this study have important implications for other regional groundwater modeling studies, especially in multi-layered aquifer systems.

Groundwater stored in the deep seated sedimentary aquifers is the most important source of water supply. The lack of sufficient groundwater recharge and the overdependence on groundwater might lead to unavailability of this precious natural resource if proper management practices are not adopted. Finite difference modelling using the MODFLOW program was carried out in the east of Riyadh city to simulate the groundwater level conditions under different abstraction scenarios. The simulated aquifer system combines the Wasia and Biyadh aquifer (composed of sandstone) and Aruma aquifer (limestone) which lies between 24°30'00"- 25°30'00" N and longitudes 47°00'00"- 48°00'00"E. The transmissivity and storage coefficient values of Biyadh aquifer are 7.0x10-3 to 7.0x10-2 m2/day and 3.7x10-4 to 9.4x10-4 respectively. The transmissivity and storage coefficient values of Wasia aquifer ranges from 6.7x10-3 to 8.5x10-2 m2/day and 2x10-4 to 2.3x10-4 respectively. The model calibration involved altering the values of model input parameters to match field conditions within certain acceptable limits to forecast the aquifer response over a period of 35 years (2015-2050). The modelling grid consisted of 20 and 24 columns with the grids spacing of 4 km for the small grids and 6 km for large grids. The results showed that though the Wasia aquifer was productive, it showed a large decline in water levels if water abstraction continued at the present rate. If the existing trends of groundwater withdraw continues; the piezometric heads in Wasia and Biyadh aquifers will decline by the year 2050. A reduction in 25% of the existing groundwater pumping rate in the well field will minimize the rate of groundwater decline in the aquifer to a considerable extent.

The Triffa plain covering about 307 km2 is located in the semiarid region of northeastern Morocco. The cover consists of Quaternary and Mio-Pliocene formations, including alluvial material, silt, sandstone, limestone, clay, and marl, underlain by a sequence of Jurassic carbonates and clastics. Two principal aquifers occur in this region: (1) An unconfined aquifer hosted by the Quaternary formations, which opens up on the coastal plain of Saidia, giving rise to the Ain Chebbak and Ain Zebda springs; and (2) a confined aquifer hosted by the underlying Liassic (Jurassic) formations, composed of limestone and dolostone. In this paper, we present a conceptual hydrogeological model for the Triffa aquifer, which opens laterally into the Saidia aquifer, based on borehole data, bedrock geology, hydrodynamic parameters, piezometric maps, and time series groundwater level and precipitation data, obtained from several meteorological stations and pumping wells. These comprehensive data were incorporated in the Geographic Information System platform and processed using groundwater modeling software, with the development of the numerical model and its limitations discussed in detail in the present work. Subsequently, we evaluated the impact of climate change on the Triffa aquifer, assuming three different climate scenarios developed by the Intergovernmental Panel on Climate Change. These were the B1—low, A1B—mean, and A1F1—extreme scenarios, which we modeled by simulating a decrease in the recharge in all of the study area up to year 2099 that would correspond to 9, 19, and 47%, respectively. The calibration of the model in steady and transient states produced a good agreement between the observed and simulated heads. The simulation of the impact of climate change on groundwater by a decrease in the recharge highlights the groundwater drawdown occurring in this region. This work can significantly help the authorities in the sustainable management and exploitation of local groundwater.

The hydraulic diffusivity gives a measure of diffusion speed of pressure disturbances in groundwater system; large values of hydraulic diffusivity lead to fast propagation of signals in aquifer. This research provides a novel design and derives spectral representation to determine hydraulic diffusivity using spectral analysis of groundwater levels coupled with time-dependent boundary adjacent to marine system and no flow boundary in aquifer system. To validate the proposed method, water levels of fluctuated boundary and groundwater well in a sandy confined aquifer were collected. The hydraulic diffusivity is then obtained by an inverse process in the non-linear complex form of spectral relationship. The method essentially is constructed on the conceptual design of natural forcing transmitted in large aquifer. It is unlike the conventional field pumping test which is only used to determine hydraulic properties of groundwater in small range around the well. Hydraulic diffusivity of the confined aquifer is determined using real observation and then checked by comparing to the published range. It suggests that without local aquifer test to estimate hydraulic diffusivity in a coastal aquifer using spectral representation with its relevant flow system and boundary has become feasible.

Wells along two regional flow paths were sampled to characterize changes in water quality and the vulnerability to contamination of the Memphis aquifer across a range of hydrologic and land-use conditions in the southeastern United States. The flow paths begin in the aquifer outcrop area and end at public supply wells in the confined parts of the aquifer at Memphis, Tennessee. Age-date tracer (e.g. SF6, 3H, 14C) data indicate that a component of young water is present in the aquifer at most locations along both flow paths, which is consistent with previous studies at Memphis that documented leakage of shallow water into the Memphis aquifer locally where the overlying confining unit is thin or absent. Mixtures of young and old water were most prevalent where long-term pumping for public supply has lowered groundwater levels and induced downward movement of young water. The occurrence of nitrate, chloride and synthetic organic compounds was correlated to the fraction of young water along the flow paths. Oxic conditions persisted for 10 km or more down dip of the confining unit, and the presence of young water in confined parts of the aquifer suggest that contaminants such as nitrate-N have the potential for transport. Long-term monitoring data for one of the flow-path wells screened in the confined part of the aquifer suggest that the vulnerability of the aquifer as indicated by the fraction of young water is increasing over time.

Analytical simulation of groundwater flow is a necessary and useful technique to predict the various behavior patterns of a groundwater system. The main aim of the present study is to derive new analytical solutions to compute the unsteady flows inside an aquifer between two parallel streams of constant and varying heads. The problems are solved by means of Laplace transform method and the solution results are verified with the results of MODFLOW. It is observed that the obtained results agreed very well with the results of MODFLOW. The solutions are carried out for two cases of ascending and descending water levels and the obtained results are compared with each other. In addition, the sensitivity of hydraulic heads to aquifer parameters and how locations of water divide change by change in aquifer parameters are investigated. In sensitivity analysis of hydraulic heads to changes in recharge rate with different values of hydraulic conductivity, thickness, and length of the aquifer, it is shown that among these parameters the length of the aquifer is the most important parameter affecting the hydraulic heads. Furthermore, the sensitivity of flow rates to recharge rates and water level change rates are analyzed.

The Thiem equation of radial groundwater flow to a well is more than 100 years old and is still commonly used. Here, deviations caused by some of its simplifications are quantified by comparing the analytical to a numerical model that allows the implementation of more complex geometries. The assumption of horizontal flow in the Thiem equation, which necessitates uniform inflow over the entire screen length of the fully penetrating well, was found to cause deviations from actual pumping wells where the pump is placed above the screen, resulting in non-uniform inflow and additional drawdown. The same applies to partially penetrating wells, where inflow peaks and additional drawdown occur, especially when the well is screened in the lower part of the aquifer. The use of the Thiem equation in the near-field of a well should thus be restricted to situations where the screen inflow is relatively uniformly distributed, e.g. when it covers large portions of the aquifer thickness. The presence of a gravel pack and a background gradient, on the other hand, are of limited importance.

The applicability of geophysical techniques has been examined for evaluating aquifer properties like transmissivity and hydraulic conductivity of coastal aquifers, Tuticorin, Tamil Nadu. The pumping test data of 10 wells are interpreted by using forward modelling to obtain the aquifer characteristics in the study area. The available vertical electrical soundings (VES) data in the vicinity of the sites of pumping test have been interpreted; and true resistivity and thickness are determined at each site in the study area. Empirical relationships are established for estimating the hydraulic parameters from the electrical data.

Involving a limited resource, the assessment of groundwater aquifers is of utmost importance. A key component of any such assessment is the determination of key properties that permit water resource managers to estimate aquifer drawdown and safe yield. This paper presents a particle filtering approach to estimate aquifer properties from transient data sets, leveraging recently published analytically-derived models for confined aquifers and using sample-based approximations of underlying probability distributions. The approach is examined experimentally through validation against three common aquifer testing problems: determination of (i) transmissivity and storage coefficient from non-leaky confined aquifer performance tests, (ii) transmissivity, storage coefficient, and vertical hydraulic conductivity from leaky confined aquifer performance tests, and (iii) transmissivity and storage coefficient from non-leaky confined aquifer performance tests with noisy data and boundary effects. On the first two well-addressed problems, the results using the particle filter approach compare favorably to those obtained by other published methods. The results to the third problem, which the particle filter approach can tackle more naturally than the previously-published methods, underscore the flexibility of particle filtering and, in turn, the promise such methods offer for a myriad of other geoscience problems.

Analyses are presented of long-term hydrographs perturbed by variable pumping/injection events in a confined aquifer at a municipal water-supply well field in the Region of Waterloo, Ontario (Canada). Such records are typically not considered for aquifer test analysis. Here, the water-level variations are fingerprinted to pumping/injection rate changes using the Theis model implemented in the WELLS code coupled with PEST. Analyses of these records yield a set of transmissivity (T) and storativity (S) estimates between each monitoring and production borehole. These individual estimates are found to poorly predict water-level variations at nearby monitoring boreholes not used in the calibration effort. On the other hand, the geometric means of the individual T and S estimates are similar to those obtained from previous pumping tests conducted at the same site and adequately predict water-level variations in other boreholes. The analyses reveal that long-term municipal water-level records are amenable to analyses using a simple analytical solution to estimate aquifer parameters. However, uniform parameters estimated with analytical solutions should be considered as first rough estimates. More accurate hydraulic parameters should be obtained by calibrating a three-dimensional numerical model that rigorously captures the complexities of the site with these data.

The aim of this work was to develop the exact groundwater flow model within a confined aquifer. We argued that, the Theis groundwater flow model is an approximation of the real formulation of the model as Theis removed some components of the equation to have a simple model. Initially, we derived an exact groundwater flow equation for a confined aquifer so as to include all high order terms that were removed by Theis and also to take into account the assumptions that were used during the derivation of the groundwater flow by Theis. Thereafter, we proved that the new groundwater flow equation has a unique solution. We then derived a new numerical scheme for a singular partial differential equation that combines the Mellin transform and the Lagrange approximation of a continuous function. The Mellin transform was used to remove the singularity in the newly developed exact groundwater flow equation for a confined aquifer. The equation became ordinary, wherein we used the Adam Bashforth method to the ordinary differential equation in the Mellin space. The inverse of Mellin was then used to get the exact numerical scheme in real space. We present the stability analysis of the new numerical scheme using the von Neumann method. Lastly, numerical simulations using experimental field data are presented. Our solution is compared to that of Theis. Our simulations show the importance of the scaling factor which was removed from the Theis groundwater flow equation. The simulations also show that the change in drawdown dependdepends on the scaling factor.

This research modeled geological and hydrogeological controls on groundwater occurrence in Oban Massif and environs southeastern Nigeria. Topographical, hydrogeological, and structural maps, including lithology samples from drilled bores, well completion, and pumping test data in the study area were procured. Collection of coordinates of rock sample locations and structural data on strike and dip of rock exposures was collected. Geological and structural information collected was overlaid on the topographical, hydrogeological and structural map and digitized to produce the geological map of the study area. Thematic map on geological groundwater prospect map of the study was prepared using multicriteria evaluation. Relative weights were assigned to various rock types based on their relative contribution to groundwater occurrence and the map was reclassified using geographic information system (ArcGIS10.1) analysis. Depth ranges of the various lithologic units from drilled boreholes were used to construct lithologic correlation section of the boreholes across the study area using RockWorks16 Program software. Hydrogeological parameters such as storativity, specific capacity, transmissivity, drawdown, pumping rate, static water level, total depth, and well yield were computed from well completion reports and aquifer test. Results shows that the geologic groundwater prospect map was categorized into very good (28.73 m2), good (9.66 m2), moderate (35.08 m2), fair (49.38 m2), and poor (77.63 m2) zones. Aquifer parameters showed ranges such as (specific capacity (1.81–31.16 m2/day/m), transmissivity (0.0033–12 m2/day), storativity (9.4 × 10−3–2.3), drawdown (2.2–17.65 m), pumping rate (0.75–3.57 l/s), static water level (0–20.5 m), and total depth (3.3–61 m). Borehole depths obtained in the basement are shallower than those in the sedimentary area. Aquifer test parameters obtained from boreholes across the study indicate better correspondence with zones identified as good water prospect in the study. It was evident that well yield is not a very reliable aquifer performance indicator, because it depends largely on the efficiency of the pump installed. Therefore, other aquifer parameters must be employed in aquifer performance assessment. The geologic formation is paramount in determining aquifer performance. The result of this groundwater occurrence is useful as a guide for groundwater developers, which engineers in water resource management and land-use planners to select suitable areas to implement development schemes and also government agencies.

Recovery pumping tests are still one of the most commonly preferred preliminary design steps in the assessment of aquifer hydraulics. The use of the existing methods would be insufficient under non-ideal aquifer conditions (i.e. heterogeneity, measurement errors, and boundary effect, etc.) which violate the Theis model assumptions developed for recovery test analysis. In this study, a new parameter estimation methodology based on the Radial Basis Collocation Method (RBFCM) was formulated to access the hydraulic parameters in a reliable, robust and accurate manner using recovery pump test. The suggested approach was established on the idea that the dimensionless time value at the pump-cessation which serves as a matching value is obtained by means of RFBCM. The proposed approach is straightforward to implement; which requires no data refinement, additional parameter, and visual match. The performance of the proposed method was tested with several aquifer conditions including homogeneous synthetic data, heterogeneous aquifer simulation and real field applications. The results confirm that the proposed method has a parameter estimation capacity as high as the available techniques in the literature and provides the practitioners to understand a more accurate portrayal of the effects of heterogeneity on the hydraulic parameters during the test process. In addition, the suggested methodology for the interpretation of aquifer recovery test can be evaluated to be employed as a diagnostic tool to identify non-ideal conditions. The potential use of RBFCM in this study was also presented as the supplement of aquifer test interpretation assessment.

A karst analog model has been developed for simulating karst aquifer systems with fracture and conduit domains in the laboratory. In this study, sixty-four experiments under different recharging and discharging conditions were carried out with the analog setup to study flow in the karst analog model. The experiments did not only provide hydraulic head data but spring discharge process as well. The experimental results were used to obtain empirical models of water hydraulic head under different hydrological conditions, which together with the spring discharge analysis aided in developing a water hydraulic head prediction model for the analog model. The results showed that water hydraulic head increased with logarithm of time and declined in step-shaped style, which can be used in karst aquifer systems research. Consequently, the study provides useful information for a better understanding of flow in karst aquifer systems.

This paper describes the development of a methodology that can be used for determining the spatial and temporal distribution of additional water volumes required to meet a defined groundwater target, such as an historical peizometric surface. The methodology is demonstrated on a case study concerned with mitigating declining groundwater levels in an alluvial aquifer intensively used for agriculture in the Lockyer Valley, Queensland, Australia. The proposed mitigation measure is the importing of large volumes of purified recycled water (PRW) from a large scale indirect potable reuse scheme into the aquifer system. The developed methodology employs both a groundwater flow model together with linear uncertainty analysis. Therefore for the case study, a distributed parameter numerical groundwater flow model was developed for the Lockyer valley alluvial aquifer system using MODFLOW, calibrated to observed groundwater levels, and further constrained by estimates of diffuse and river recharge from water balance studies. The model was used to simulate groundwater levels in the aquifer over a 20-year period. Optimal spatial and temporal distribution of volumes of imported water required to mitigate declining groundwater levels over that period were then estimated, using a modified version of the MODFLOW General Head Boundary (GHB) package. Uncertainty in the predicted import volumes was estimated using linear bayesian analysis principles. The relative worth of data from each observation bore within the groundwater monitoring network was also assessed in terms of the extent to which predictions of import water volumes were made more reliable when furnished with that data. Application of the methodology to the Lockyer alluvial aquifer system illustrated the suitability of the developed methodology for estimating the additional water volumes required for managed aquifer recharge or groundwater substitution schemes in similarly over-exploited aquifers.

In this study, 50 Vertical Electrical Soundings (VES) were carried out in the region, including 14 near existing boreholes for comparison. Aquifer parameters of hydraulic conductivity and transmissivity were obtained by analyzing pumping test data from existing boreholes. An empirical relationship between hydraulic conductivity (K) obtained from pumping test and both resistivity and thickness of the Pan-African aquifer has been established for these boreholes in order to calculate the geophysical hydraulic conductivity. The geoelectrical interpretation shows that almost all aquifers are made of the fractured portion of the granitic bedrock located at a depth ranging between 7 and 84 m. The hydraulic conductivity varies between 0.012 and 1.677 m/day, the resistivity between 3 and 825 Ωm, the thickness between 1 and 101 m, the transmissivity between 0.46 and 46.02 m2/day, the product K σ between 2.1 × 10 −4 and 4.2 × 10 −4.

This paper presents an investigation into increased deformation of Aquifer II caused by groundwater pumping from the aquifer in Changzhou, China. As groundwater levels of aquifers have been decreasing in recent decades due to uncontrolled water pumping, land subsidence is becoming a serious geohazard in Changzhou. Based on recently reported field data, the compression of aquitards has not increased compared to that of aquifers with the same scale of layer thickness. The Cosserat continuum model was adopted to analyse the observed phenomenon in this study. A classic Cauchy continuum model is also used for comparison. The comparison between these two models indicates that the proposed approach can interpret the increased deformation well, and the classic Cauchy continuum model underestimates the aquifer deformation as it does not consider shear displacement and macro-rotation. A discussion on the relationship between the groundwater level in the aquifer and subsidence is then undertaken. The results show that the severity of the annual subsidence is correlated with the variation in groundwater level in Aquifer II. To mitigate the subsidence hazards, countermeasures should be adopted to avoid the shear stress in aquifers which results from the high hydraulic gradient, by the appropriate allocation of pumping wells and by restricting groundwater withdrawal volume from each pumping operation.

Groundwater models are vulnerable to uncertainties, especially those that are developed based on incomplete knowledge of the hydraulic parameters. Transmissivity is often the most uncertain parameter in groundwater modeling. This work evaluates the effect of the spatial variability of transmissivity on the outputs of the groundwater flow model of the Takelsa multilayer aquifer. The study was based on a combination of deterministic and stochastic modeling. Groundwater flow modeling and stochastic simulations were made using the PMWIN software (a version of MODFLOW). Initially, the groundwater flow model was developed in the steady state. The criteria used for the calibration process were based on the comparison between the observed and the simulated hydraulic level. Then, a stochastic approach was used and 100 simulations of transmissivity were performed. The simulated transmissivity values were used to recalculate the hydraulic head and the water budget of the Saouaf deep aquifer. Finally, the consequent 100 results obtained by running MODFLOW were analyzed. The results showed variations in the hydraulic head levels, but the flow direction remained the same. The impact of the spatial variability of transmissivity on the water budget shows a range of inflow and outflow rates of Saouaf aquifer, with special relevance to the sea intrusion which may cause a probable deterioration of the quality of the groundwater.

Water management is one of the most challenges in Algeria, a semi-arid Mediterranean country confronted to a serious water stress. The country will have to endure, beyond 2025, a situation of chronic water penury, adding an excessive pollution of the majority of groundwater reservoirs. The management of water resources by combined approach using hydrogeological model and nitrates evolution model was experimented in the Middle Soummam valley. The alluvial aquifer, offering good hydrodynamic and geometrical characteristics, is over-exploited, providing in drinking water Akbou and Tazmalt cities and irrigation perimeters. If exploitation continues at these steady paces, the depletion of the water resource and the hydrochemical imbalance will be inevitable. On the one hand, the results of hydrodynamic model, based on an increase of the water takings and simulated needs from 24.71 Mm3/year in 2015 into 39.69 Mm3/year in 2030, show a critical withdrawal. The aquifer budget expresses the inversion of flow between the wadi and the aquifer where the wadi feeds the groundwater reservoir. This hydrodynamic inversion was attributed to simulated pumping rates which increased and exceeded 100,000 m3/day, but the aquifer was partially relieved by the weight of the exploitation through Tichy Haf dam. The water management strategy adopted in this study was based on management measures promoting zones, which have been delimited between Tazmalt and Akbou, and containing important water quantities available in the axis of the valley. However, according to the depleted in isotopes of 18O and 2H, which could be explained by the influence of a paleoclimatic effect and suggested that the aquifer recharge would have largely been made under a colder climate, pumped groundwater could be old, and the implementation of new pumping sites has been studied minutely. On the other hand, the hydrogeochemical modelling allowed following nitrates concentrations in order to project their evolution. Four wells on 25 react in face to the imposed conditions in each scenario simulated until 2030, showing inertia of pollution, and confirmed after three series of tests. This inertia would be related to the hydraulic gradients and hydraulic conductivities, aquifer thickness and recharge. The low hydraulic gradients lead to a rather slow flow velocity and thus to an inertia in the dispersion of nitrates, with a mass transport weakened by the hydrodynamic conditions. It is also related to the aquifer thickness; when the aquifer is powerful (65–85 m), the stock of water would be important and allows a dilution process. The reverse is true for the simulated boreholes where the concentrations remain invariant; the aquifer is less powerful (32–37 m). Finally, the recharge effect through the rain was evoked; the aquifer is unconfined, and the rain water and pollution that reached the piezometric level can remain in position in slow hydrodynamic conditions. The methodology was demonstrated through a combination of monitoring and modelling for both water quantity and quality and the importance to use numerical models to support water resources management strategy in the Mediterranean aquifers.

Parameter estimates of artesian aquifers where piezometric head is above ground level are largely made through free-flowing and recovery tests. The straight-line method proposed by Jacob-Lohman is often used for interpretation of flow rate measured at flowing artesian boreholes. However, the approach fails to interpret the free-flowing test data from two artesian boreholes in the fractured-rock aquifer in Table Mountain Group (TMG) of South Africa. The diagnostic plot method using the reciprocal rate derivative is adapted to evaluate the artesian aquifer properties. The variation of the derivative helps not only identify flow regimes and discern the boundary conditions, but also facilitates conceptualization of the aquifer system and selection of an appropriate model for data interpretation later on. Test data from two free-flowing tests conducted in different sites in TMG are analysed using the diagnostic plot method. Based on the results, conceptual models and appropriate approaches are developed to evaluate the aquifer properties. The advantages and limitations of using the diagnostic plot method on free-flowing test data are discussed.

Prediction of water table fluctuations in response to proposed schemes of recharging and pumping is important to make judicious selection of an appropriate scheme out of many schemes to achieve the preset objective of sustainable management of groundwater resources without compromising the regional water balance. This is achieved by solving groundwater flow equation with suitable initial and boundary conditions, aquifer parameters, and recharge/pumping parameters. Earlier, analytical solutions were developed to predict water table fluctuations in aquifer due to time varying recharge rate from multiple basins considering spatially uniform recharge rate for the entire basin area. However, the recharge rate may vary spatially within a single basin due to many factors such as variation in the height of water column above the base of the basin, degree of siltation of the base of the basin etc. In the present work, we develop an analytical solution for modeling of water table fluctuations in an anisotropic aquifer due to intermittently applied spatio-temporally varying rate of recharge from multiple basins and pumping from multiple wells arbitrarily distributed within the model domain. In the present solution, wells are treated as point sources, which helps in reducing numerical artifacts. Some earlier obtained analytical solutions are the special cases of the present solution.

A modeling system for the stochastic simulation and management of the overexploited groundwater resources of Lake Karla Basin in Central Greece is presented. The uncertainty of the hydrogeological environment which arises from the lack of the hydraulic conductivity data and aquifer’s heterogeneity necessitates the stochastic simulation of the underlying aquifer. For the conditional stochastic simulation of hydraulic conductivity, the geostatistical approach was used generating Monte-Carlo realizations. The impact of Lake Karla (or reservoir) restoration and the accompanying projects on the aquifer, is examined through various management scenarios taking into consideration this parameter uncertainty. The target of the restoration plan is to rehabilitate aquifer’s water table. This will be achieved through shutting down a great number of irrigation wells, as the irrigation needs of cultivations will be covered by the reservoir. The project with the highest environmental impact on the aquifer is the construction of 50 water supply wells at the lakeside zone of Lake Karla. Nowadays, due to the intense agricultural cultivation, the study area faces a serious water deficit problem, which has led to the over-exploitation of non-renewable groundwater and to a dramatic drawdown of aquifer’s water table. The results of the stochastic simulation and management indicates that the operation of the new water supply wells will lead, despite the operation of the new reservoir, to a further drawdown of aquifer’s water table, and will increase the effect of parameter uncertainty on hydraulic heads estimation by groundwater model.

While in constant head aquifer, groundwater level before pumping and after recovery attain a constant value, it is quite challenging to estimate the actual discharge value in an atoll aquifer where the head fluctuates with tides. Lens shaped atoll aquifers are fragile in nature and pumping causes the water table to fall which could further aggravate sea water intrusion. Thus the objective of the study is to propose an alternative method and demonstrate the importance of tide-induced head fluctuations in analysing the aquifer parameter in atoll environment. The solution to a one-dimensional unsteady groundwater flow model in an atoll aquifer with sinusoidal fluctuations of the tide shows that the tidal response method (TRM) is reliable and safe in comparison to conventional methods of aquifer characterization. The aquifer parameter is described by the ratio of transmissivity to storage coefficient, known as hydraulic diffusivity. The observations of the tide and groundwater levels using loggers at 16 wells over the Kalpeni Atoll, Lakshadweep, India show that with distance from the coast, tidal efficiency decreases roughly exponentially and time lag increases linearly. The calculated hydraulic diffusivity (T/S) values using TRM range from 764 to 1,090,000 m2/day. In parallel, pumping tests are conducted in six shallow dug wells to validate the TRM data. Draw down and recovery data during pumping test are influenced by the tide-induced head fluctuations. The effect complicates the interpretation of the drawdown data. After subtracting the net tidal effects from the draw down data, the calculated parameter values are observed to be closer to the estimated parameter values from TRM.

Groundwater resource investigations primarily involve inferring groundwater levels and recharge sources from factors such as the distributed location and range, subsurface geological structure, and flow paths of groundwater sources. This study conducted an investigation on the underground aquifer at the downstream of the Chih-Ben Creek basin, Taiwan. In addition, convenient, rapid, and accurate two-dimensional electrical resistivity tomography (ERT) was employed for evaluations. The cross-sectional ERT image indicates that the low-resistivity region in the stratum at survey line CB01 may be a groundwater deposit or fracture zone. This region can be divided into three major segments. The segment that is 0–50 m from the survey line exhibits a decreasing trend and is thus inferred to be a recharge source. Survey line CB02 can be generally divided into four layers, with the second layer containing a greater amount of groundwater. This layer is an aquifer with a depth of approximately 25–100 m below the ground surface and 75–100 m in thickness. The base of the aquifer slopes toward the east and primarily possesses a lithological composition of slate and sandstone with explicit and fractured joints.

A three dimensional model is presented for the simulation of seawater intrusion in coastal aquifers by considering the development of a transition zone and thus the variable density flow approach. The model is applied to a heterogeneous coastal aquifer to study the effects of the pumping rate, the salinity of freshwater inflow and the thickness of the aquifer, on the degradation of pumped water quality through wells in certain location. Even for an optimum pumping scheme solution based on a simple two-dimensional flow model, we simulate freshwater degradation in pumped water which depends on the salinity of freshwater inflow and aquifer thickness.

Aquifer parameters are useful for modeling sea water intrusion and other groundwater management issues in coastal areas. Oscillations in tide-induced groundwater levels contain important information of the properties of coastal aquifers and measurements of tidal effects can be employed to estimate the aquifer parameters. The solution to the transient groundwater flow model in a coastal confined aquifer with a sinusoidal fluctuation of the tide shows that the amplitude of groundwater levels is smaller than the tide, the tidal efficiency decreases exponentially with distance from the coast and the time lag increases linearly with distance from the coast. The aquifer property described by the ratio of storativity to transmissivity can be estimated if the amplitude (or tidal efficiency) and the time lag of groundwater levels are obtained based on filed measurements of tidal effects. Principle of these tidal methods is presented in this article, including those with one observation well and two observation wells. Hourly observations of the tide and groundwater levels at 14 observation wells in the coastal aquifer near Beihai, China are used to illustrate the application of these methods. The estimated ratio of storativity to transmissivity of the confined aquifer ranges from 1.66 × 10–7 to 4.84 × 10–7 d/m2. For a given transmissivity of 750 m2/d, the storativity of the aquifer is in the range 1.245 × 10–4 to 3.63 × 10–4.

Long-term groundwater withdrawal has caused severe land subsidence in Shanghai, in which compaction of aquifer units has taken an important role. The compaction characteristics of aquifer units are closely related to the changing patterns of groundwater levels the units have experienced. They may be elastic, elasto-plastic, visco-elastic, or visco-elasto-plastic. Several compaction models are discussed and used to calculate the compaction of the aquifer units in Shanghai. Compared with other models, it is found that double-yielding visco-elasto-plastic model can capture the compaction characteristics of aquifer units and more reasonably simulate the compaction of aquifer unit under complex changing patterns of groundwater level. In particular, the double-yielding model can describe the plastic compaction when the average groundwater level declines but is higher than the historically lowest level and the obvious visco-plastic compaction when the groundwater level is lower than the historically lowest level, which is a popular deformation characteristic for aquifer units in Shanghai.

Aquifer performance was tested in 24 locations to assess the groundwater potential of the hard rock terrain in the Chittar–Uppodai watershed of the Tambaraparani River basin. Geologically, the area consists of biotite gneiss, charnockite, and quartzite. The aquifer characteristics, such as transmissivity (T), the storage coefficient, specific capacity, optimum yield, and the recovery rate were calculated. The drawdown transmissivity was determined using Jacob’s straight-line method, while the recovery transmissivity was determined by the Theis method. The drawdown transmissivity was low in the western areas, particularly at Kadayanallur, and was higher in the other areas. The recovery transmissivity was high in the western area, and, with the exception of Gangaikondan, was low at other locations. The assessment indicates that there is groundwater potential in the western part of the study area because of favorable results for recovery drawdown, aquifer thickness, and specific capacity.

Use of deep groundwater is becoming an important issue in Bengal Basin due to water quality problems in upper aquifers in many areas. Still >50 % of cultivable land in the model area has the potential for future irrigation. Prior to development of deep aquifers it is important to know the trend of flowpaths from recharge zone and travel time of stored water in field geologic conditions and development stresses, which is the principal objective of this study. A three-dimensional model was used for this study to simulate groundwater flow. Model simulation results depict that flowpaths and travel time of groundwater are primarily controlled by hydrogeologic characteristics. However, the recharge zone for different aquifer units is about the same in different conditions with variation of travel time. Continued irrigation abstraction from the shallow aquifer may decrease vertical percolation of recharge water to deeper aquifers. The water of the shallow, i.e., the 1st aquifer, generally has a higher head than water in the main, i.e., the 2nd aquifer. Water from the shallow aquifer may move downward into the deeper units through aquitard windows. The water level of the deep, i.e., the 3rd aquifer, is higher than that of the main aquifer. The arsenic or chloride-rich groundwater in the upper aquifers is not likely to be drawn into the deep aquifer under conditions of moderate use of the deep aquifer.

The vertical electrical soundings (VESs) are carried out in 24 selective locations of Chapai-Nawabganj area of northwest Bangladesh to determine the transmissivity and hydraulic conductivity of the aquifer. Initially, the transmissivity and hydraulic conductivity are determined from the pumping data of nearby available production wells. Afterwards, the T and K are correlated with geoelectrical resistance and the total resistivity of the aquifer. The present study deciphers the functional analogous relations of the geoelectrical resistance with the transmissivity and the total resistivity with the hydraulic conductivity of the aquifer in northwest Bangladesh. It has been shown that the given equations provide reasonable values of transmissivity and hydraulic conductivity where pumping test information is unavailable. It can be expected that the aquifer properties viz. transmissivity and hydraulic conductivity of geologically similar area can be determined with the help of the obtained equations by conducting VES experiments.

This paper investigates tide-induced groundwater fluctuation and submarine groundwater discharge (SGD) in a leaky inhomogeneous coastal aquifer system with an upper unconfined aquifer, a lower confined aquifer, and an aquitard between them. The upper left aquifer is formed due to land reclamation. The SGD defined as the groundwater flow from land into the sea is controlled mainly by the hydraulic gradient between land and sea. An analytical expression is developed to discuss and assess the effect of inhomogeneity on the groundwater head fluctuation in the leaky aquifer system. Joint effects of aquifers’ parameters such as leakage and hydraulic diffusivity on the groundwater head fluctuation and SGD are investigated. The predicted results from the analytical expression indicate that the groundwater head fluctuation in both unconfined and confined aquifers is dependent on dimensionless leakages and increases with dimensionless hydraulic diffusivity.

Nanoscale zero-valent iron (nZVI) has recently gained great interest in the scientific community as in situ reagent for installation of permeable reactive barriers in aquifer systems, since nZVI is highly reactive with chlorinated compounds and may render them to harmless substances. However, nZVI has a high tendency to agglomerate and sediment; therefore it shows very limited transport ranges. One new approach to overcome the limited transport of nZVI in porous media is using a suited carrier colloid. In this study we tested mobility of a carbon colloid supported nZVI particle ""Carbo-Iron Colloids"" (CIC) with a mean size of 0.63 mm in a column experiment of 40 cm length and an experiment in a two-dimensional (2D) aquifer test system with dimensions of 110 × 40 × 5 cm. Results show a breakthrough maximum of 82 % of the input concentration in the column experiment and 58 % in the 2D-aquifer test system. Detected residuals in porous media suggest a strong particle deposition in the first centimeters and few depositions in the porous media in the further travel path. Overall, this suggests a high mobility in porous media which might be a significant enhancement compared to bare or polyanionic stabilized nZVI.

Providing a sound basis for aquifer management or remediation requires that hydrogeological investigations carried out to understand groundwater flow and contaminant transport be based on representative data that capture the heterogeneous spatial distribution of aquifer hydraulic properties. This paper describes a general workflow allowing the characterization of the heterogeneity of the hydraulic properties of granular aquifers at an intermediate scale of a few km2. The workflow involves characterization and data integration steps that were applied on a 12-km2 study area encompassing a decommissioned landfill emitting a leachate plume and its main surface water receptors. The sediments composing the aquifer were deposited in a littoral–sublittoral environment and show evidence of small-scale transitional heterogeneities. Cone penetrometer tests (CPT) combined with soil moisture and electrical resistivity (SMR) measurements were thus used to identify and characterize spatial heterogeneities in hydraulic properties over the study area. Site-specific statistical relationships were needed to infer hydrofacies units and to estimate hydraulic properties from high-resolution CPT/SMR soundings distributed all over the study area. A learning machine approach was used due to the complex statistical relationships between colocated hydraulic and CPT/SMR data covering the full range of aquifer materials. Application of this workflow allowed the identification of hydrofacies units and the estimation of horizontal hydraulic conductivity, vertical hydraulic conductivity and porosity over the study area. The paper describes and discusses data acquisition and integration methodologies that can be adapted to different field situations, while making the aquifer characterization process more time-efficient and less labor-intensive.

This paper discusses a geostatistical approach to model a groundwater aquifer in 3-D. The study aims at utilizing geostatistics as a tool for characterizing zones of better-water quality in a brackish-saline aquifer. In particular, the geostatistical model was constructed to characterize the aquifer’s salinity, represented by total dissolved solids (TDS), using logs of porosity and resistivity. Quality-checked estimated TDS vertical profiles were employed to construct and model horizontal and vertical semivariograms. Parameters of semivariogram models were used to develop both the kriging plan and the generated model. Results of this modeling process are shown in the form of horizontal salinity distribution maps. The aquifer was sliced into 20 layers, each 20 m thick, to represent its overall thickness. Salinity layers maps reflect vertical stratification of TDS concentrations in the aquifer and show that water quality deteriorates with depth and toward the northern part of the aquifer. Relatively better-quality water (TDS ≤10,000 mg/l) can be found at depths between 100 and 250 m below the aquifer’s top in both eastern and southeastern parts. Water in the same interval to the western and southwestern parts reflects the presence of higher TDS concentration. From a planning point of view, it is more feasible to target the eastern part of the aquifer for pumping and desalination purposes. In addition, the generated model could be utilized as an initial condition for flow simulation.

In 1967, the US Geological Survey (USGS) published the results of 141 pumping tests carried out throughout the Pakistani Punjab to establish representative hydraulic parameters of its large aquifer. Many authors have since concluded that the USGS had over-estimated the horizontal hydraulic conductivity (k r) by 25–100 %, leaving vertical anisotropy and aquifer depth unresolved. No test wells have ever been drilled below 450 m to reach the base of the aquifer, although petroleum explorations mention depths between 1,500 and 4,500 m. After comparison and re-evaluation of all related papers, this study concludes that the USGS interpretation was correct, that its hydraulic values still stand without change, and that the USGS’s applied distance drawdown interpretation is valid to prevent influence of partial penetration on the results. This study also uniquely resolved vertical anisotropy and aquifer thickness by using early- and late-time drawdowns separately and proper scaling of the coordinates, which has often been omitted. With appropriate scaling, all interpretations match the data. The representative hydraulic aquifer values are: k r = 65 m/d, vertical anisotropy k r/k z = 25 and aquifer depth 500–1,500 m. The conclusion is that these values can be used, at least as first estimates, for groundwater studies in the Pakistani Punjab.

Managed aquifer recharge (MAR) will play an increasingly important role in solving water scarcity. The performance of MAR systems depends primarily upon local hydrogeology. Greatest opportunities for improvement in the implementation of MAR systems lie in the targeted application of conventional and advanced technologies to improve aquifer characterization. Surface geophysics (e.g., VES, TDEM, and seismic reflection and refraction) generally provide low resolution, but areal extensive data on subsurface hydrogeology. Times series of relative microgravity measurements have been used to map changes in both vadose and phreatic zone storage and to augment monitoring well systems. Surface nuclear magnetic resonance (NMR) has the potential to provide quantitative data on water-filled porosity and pore size distribution and, in turn, an estimate of hydraulic conductivity. Standard borehole geophysical logging techniques can provide coarse-scale data on aquifer heterogeneity. Advanced borehole logging techniques, such as NMR, microresistivity imaging, and gamma ray spectroscopy, have been used in MAR projects in the USA and UAE to provide fine-scale petrophysical data (e.g., porosity, porosity-types, and pore-size distribution). Groundwater modeling is used in MAR investigations to evaluate system feasibility and to optimize system design and operation. Opportunities to improve groundwater modeling exist through the application of advanced reservoir simulation platforms that allow for the processing and integration of available lithological, geophysical, and aquifer testing data and their subsequent incorporation into groundwater flow models. Advanced groundwater modeling programs are available that allow for the simulation of complex aquifers such as dual-porosity systems and variable density.

During an aquifer test, the depression cone covers various geological formations, and hence, their reflections in time-drawdown data yield noncontinuous scatter of points on double logarithmic paper for type curve matching so as to obtain the aquifer parameters. In this way, transmissivity and storativity parameters are subject to local changes. Although changes are more obvious during the early stages of pumping, as the depression cone expands, the aquifer parameters become more stable, since they represent the average values for the aquifer material under the influence domain of the depression cone. In practice, single type curve matching is sought for the aquifer parameter identification. This paper presents a partial matching for aquifer parameter variation determinations. The application of the methodology is presented for extensive aquifer test data from the Chad Doab area in Pakistan. The partial matching procedure provides a set of aquifer parameter estimations, and the final parameters can be taken as simple as the arithmetic average, but better in the form of weighted average by adapting matching durations as weights. The percentage differences between the classical and partial type curve matching transmissivity (storativity) estimates are about 23 % (40 %). In conclusion, the classical type curve matching procedure yields under estimations in the aquifer parameter values.

A methodological procedure is proposed for determining the renewal period (RP), which expresses the ratio of total storage to recharge of carbonate aquifers, and it was applied to the overexploited moderate-size Becerrero carbonate aquifer (southern Spain). To this end, geological and subsurface data—time domain electromagnetic (TEM) soundings and borehole logs—were integrated to construct a three-dimensional (3D) geological model of the aquifer. The interconnected porosity was estimated by analyzing 73 rock samples. The resulting 3D geometrical model makes it possible to quantify the fractions of the aquifer having a confined or unconfined behaviour. Based on the total storage capacity (179 · 106–514 · 106 m3) and available aquifer recharge estimation (4.8 · 106–6.4 · 106 m3/year), an RP between 37 and 106 years is obtained. In view of the RP, an exploitation rate slightly lower than the average recharge of the system is recommended, so that the piezometric level will be stable but below the discharge head that is produced through the springs in natural conditions. The proposed methodology to obtain an aquifer RP and the management strategies designed accordingly are of broad interest, especially for carbonate aquifers, which are abundant in arid and semiarid regions.

Compensation pumping is used to alleviate deficiencies in streamflow discharge during dry seasons. Short-term groundwater pumping can use aquifer storage instead of catchment-zone water until the drawdown reaches the edge of the stream. The capacitance is a complex, dimensionless parameter of an aquifer system that defines the delayed effect on streamflow when there is groundwater pumping. This parameter is a function of aquifer hydraulic characteristics, pumping time, and distance between the well and stream edge; the latter can involve stream leakance and vertical leakance of an associated aquitard. Three typical hydraulic cases of combined water systems (major catchment-zone wells close to the stream and compensation pumping wells) were classified depending on their capacitance structure (i.e. the relationship between surface water and groundwater): (1) perfect hydraulic connection between the stream and aquifer; (2) imperfect hydraulic connection between the stream and aquifer; and (3) essentially imperfect hydraulic connection between the stream and the underlying confined aquifer. The impact of various hydraulic characteristics and engineering factors on stream depletion was examined by conceptual and numerical modeling. To predict the suitability and efficiency of a combined water system application, regression tests were undertaken on unit stream depletion and capacitance, and power dependencies were defined.

Korba aquifer is one of the most typical examples of overexploited coastal aquifer in the Mediterranean countries. In fact, from 1985, a considerable piezometric level drop, water salinization, and seawater intrusion were registered in the aquifer. In December 2008, Tunisian authorities initiated a general plan to groundwater management in order to augment groundwater resources, restore the piezometric levels, and improve water quality. The plan consists of artificial recharge of groundwater used treated wastewater through three infiltration basins. During the first 4 years (from December 2008 to December 2012), 1.41 Mm3 of treated wastewater was injected to the Korba aquifer. This study presents a hydrogeological assessment of groundwater evolution during the recharge processes. In this study, 32 piezometric and chemical surveys of 70 piezometers and observed wells are used to present hydrogeological investigation and water quality evolution of wastewater reuse through artificial recharge in Korba coastal aquifer. The piezometric evolution maps are used to specify the positive effect in groundwater level that exceeding 1.5 m in some regions. The interpretation of salinity evolution maps are used to indicate the improving of groundwater quality.

This paper deals with the analysis of groundwater condition in an alluvial aquifer system underlying Kushabhadra-Bhargavi River basin of Odisha, India. The rainfall data and river-stage data of the Kushabhadra River were analyzed for the periods of 1995–2009 and 1991–2010, respectively. Using the available lithologic data, geologic profiles along North-South and East-West sections were prepared and stratigraphy analysis was performed to characterize aquifers and confining layers present in the river basin. The results of stratigraphic analyses indicated that a two-layered aquifer system consisting of an unconfined aquifer and a confined aquifer exists in the study area. The thickness of unconfined aquifer varies from 3.4 to 46.5 m, whereas that of confined aquifer varies from 3.1 to 80.3 m over the basin with an interconnecting confining layer of thickness ranging from 2.1 to 60.0 m. The rainfall-groundwater dynamics and hydraulic connectivity were also investigated for gaining insights into groundwater characteristics. The analysis of groundwater levels indicated that the correlation among the 14 sites is better for most pairs of the sites (r = 0.50 to 0.96) in case of pre-monsoon season’s data and annual data as compared to monsoon and post-monsoon season’s data. This indicates good hydraulic connectivity among the observed sites in the study area. The significant seasonal groundwater fluctuations in the study area indicate appreciable recharge to the aquifer during the monsoon season. The findings obtained and insights gained from this study can be helpful for the water managers and decision makers to understand groundwater dynamics for the efficient planning and management of vital groundwater resources in the region. It is recommended that groundwater monitoring should be continued at more sites to understand long-term spatio-temporal characteristics of groundwater in the study area.

Interdisciplinary and comprehensive field work combining hydraulic and geophysical experiments yielded an improved understanding of the fractured and partly karstified Kohlenkalk aquifer in the Hastenrather Graben near Aachen, Germany. The aquifer is used for drinking water production and located in a geologically and tectonically complex area shaped by various tectonic events. A workflow which combines implicit 3D structural modeling with hydrogeological conceptual model building enabled determining hydrogeological boundary conditions at specific boundary cross sections, calculating the aquifer volume, and analyzing the hydraulic influence of faults on the aquifer system. Electrical resistivity tomography, seismic refraction tomography, well logging, and a coring campaign combined with available maps and additional literature research served as basis for the setup of the 3D structural model. This 3D model comprises all important structural elements, including the fault system, deep folded structures, and thrusts in the graben center. Integration of geological structure and hydraulic studies yielded a conceptual model of the hydrogeology, describing the Kohlenkalk aquifer and neighboring layers. Hydraulic conductivity of the aquifer system varies between 6.0 × 10−7 and 6.4 × 10−4 m s−1 with a decreasing trend from the NE graben shoulder to the graben center. Analysis of piezometric heads and resulting groundwater contour maps indicated four hydrogeological units which are partly limited by faults. Data on groundwater recharge as well as anthropogenic influences on the groundwater resources are part of the conceptual model.

A groundwater flow and mass transport model simulated the remediation capability of non-pumped wells with filter media placed in backfilled trenches in homogeneous and heterogeneous aquifers. For each of five homogeneous and heterogeneous aquifer settings, the model identified a base configuration of wells for a backfill hydraulic conductivity equal to the mean of the aquifer (1.5 m/d). Base configurations comprised the least number of wells necessary to contain and remove a contaminant plume. For each setting, the model also simulated base configurations with backfill hydraulic conductivity one and two orders of magnitude lower and one and two orders of magnitude higher than the mean of the aquifer. In general, backfill with a hydraulic conductivity equal to the mean of the aquifer, or slightly higher, outperformed other scenarios.