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Geological deformations like anticlines have a prominent role in aquifer system functioning. Structural deformations control erosion patterns, areas of nondeposition, lateral facies variations and thickness variations. The nature and geometry of geological bodies have a major impact on the aquifers and interconnections between them. To characterize these features and to quantify their influence on overall hydrogeological functioning, a multidisciplinary approach is proposed at a local scale. In southwestern France, the Aquitaine Basin contains a regional multilayered aquifer system affected by numerous anticlines. The Villagrains-Landiras anticline is a major anticline of the Aquitaine Basin, and near its axis is the subcropping Cenomanian aquifer; thus, the Cenomanian aquifer has potential for drinking water supply. An extensive research program was developed, including reconnaissance drilling, water level measurements, geochemical analyses, and petrophysical tests, and the results were combined with existing data. This integrated work precisely defined the complex architecture of the aquifer and confining units linked with the uplift and the polyphase erosion of the anticline. It resulted in the characterisation of the deposits’ geometries, lithology, and aquifer properties. The areas of aquifer interconnection have been defined and recharge flows have been estimated. A new groundwater circulation pattern constrained by isotopic water residence times was developed. A new geological model was built, which enables a rethink of the local functioning of the aquifer targeted for drinkable-water supply, but also it allows an understanding of the importance of anticline structure on the recharge conditions of the aquifers of this regional multilayered aquifer system.

A quantitative classification of carbonate aquifers based on hydrodynamic behaviour is introduced. This type of classification is necessary to understand the physical functioning of carbonate hydrogeological systems and to provide a realistic interpretation of field data. Carbonate aquifers are generally considered as karst systems; however, geomorphology and aquifer geology alone are insufficient for determining hydrodynamic behaviour. Analysis of spring and well hydrographs based on analytical solutions is applied to establishing a quantitative classification. A base-flow recession coefficient is used as an indicator of hydrodynamic behaviour. Detailed numerical analyses suggest that carbonate systems can be classified into two distinct groups based on hydrodynamic behaviour. The physical processes depend on a combination of hydraulic and geometric parameters, and their functional relationships can be quantitatively determined. The proposed classification methodology involves making an assumption about aquifer type, estimating aquifer properties from hydrograph data, and comparing the results with field observations. The proposed classification methodology was applied to aquifers representing the two groups of carbonate systems. In both cases, the applied methods revealed crucial information about hydrodynamic functioning of the investigated systems. While the studied limestone aquifer showed karstic hydrodynamic behaviour, the investigation of a dolomite aquifer disproves a priori assumptions on karstic flow conditions. Dolomite aquifers represent an ambiguous group of carbonates and require caution in the selection of investigation tools and interpretation of hydrogeological data. The introduced methodology provides a reliable means of determining the hydrodynamic functioning of an aquifer and supports the quantitative classification of carbonate hydrogeological systems.

The Maastrichtian sediments of Anambra Basin, south western Nigeria was studied for grain characteristics and maturity of the sediments, so that by combining sedimentological characteristics, maturity and its paleoenvironment of deposition of the Ajali sandstone, in order to ascertain the aquifer properties of the groundwater within the study area and by extension the availability of drinking water for both the urban and rural settlers. Grain size analysis (51 samples) and heavy mineral analysis (15 samples each) were analyzed. The textural parameters show that the Sandstone are medium sand, poorly to moderately sorted, coarse to strongly coarse skewed with mesokurtic to leptokurtic grains. The heavy minerals present in lithologic sand and sandstone units of Ajali Formation are mainly zircon, rutile, tourmaline, apatite, staurolite, and opaque minerals (Goethite, hematite, ilmenite), these heavy minerals found in the sandstone are associated with igneous and metamorphic source which indicates that these maastritchian sediments are from basement complex rock The ZTR index of 67.96% and the values of the kurtosis indicates a sub-mature sandstone to mature sandstone, which gives an excellent aquifer properties. Also, the paleoenvironment of deposition of the Maastrichtian sediments is Fluvial. The sand and sandstone bodies deposited in a fluvial system have sheet-like geometries and due to the differences in the extent of aquifer compartmentalization, Sandstone deposited in fluvial environment normally has better hydraulic conductivity which again reveals a good aquifer property. The sedimentological characteristics for the Sandstone exposed at Fugar and environs, is a coarsening upward sequence (increasing grain sizes) with a progressive increase in sorting. since hydraulic conductivity increases with increasing grain sizes and sorting, hence, excellent aquifer characteristics for the groundwater within the study area. The foregoing revealed that the aquifer geometry and properties of the study areas is favourable for the availability of drinking water for both the Urban and rural dwellers within these communities. Keywords: Aquifer geometry, groundwater, hydraulic conductivity, Anambra Basin

The Yucatan Peninsula karst aquifer in southeastern Mexico is important because it is the only source of freshwater supply in the region. Along the eastern coast, the aquifer behaves as a shallow unconfined aquifer, and one of its main characteristics is the development of a complex network of karstic conduits. Electrical resistivity tomography (ERT) is a geophysical technique that provides reliable information on aquifer properties that can be applied to karst. With this in mind, ERT surveys (with dipole-dipole and Wenner arrays) together with vertical profiles of groundwater electrical conductivity were obtained in the northeast of Yucatan Peninsula in the Akumal zone. The objective was to evaluate the characteristic structure of the unsaturated and saturated areas, and to determine the importance of factors at a local level that affect the thickness of the freshwater lens, as well as groundwater flow directions near the coast. The results of the ERT sections show a thin vadose zone with resistivity values greater than 1,052 Ωm and a saturated zone with resistivity values that vary from 1 to 1,052 Ωm, and show the presence of dissolution conduits and fracture zones that are affecting the freshwater lens of the aquifer. In addition, water-table measurements show the role of fracture networks in the groundwater flow. The overall results indicate conditions for a possible microbasin in the Akumal zone, highlighting the importance of local fractures, which could work as groundwater divides along the eastern coast of the Yucatan Peninsula.

The hydraulic characterization of a highly anthropized coastal aquifer in France is presented. The current industrial operations of the study site prevent the use of standard ‘active’ hydrogeological investigation methods (pumping, slug tests). However, the studied field is bordered on its north-western side by a channel directly connected to the sea, which allows for characterization of the hydraulic properties of the aquifer from its natural responses to the channel’s tidal signal. Piezometers (37) were monitored, from which oscillatory water-level responses (amplitude and phase-offset) to the tidal signal were extracted through linear regression and fast Fourier transform. A two-dimensional (2D) numerical model in the frequency domain was built to simulate the oscillations. The anthropic buried walls and barriers existing at the site are represented as 1D elements in a 2D model representing the properties of the aquifer. A deterministic inversion process optimizes the spatial distribution of aquifer properties and anthropic-structure properties in the model, in order to minimize the differences between the responses simulated with the model and those measured in the field. The results of the characterization on this complex study case (flows highly constrained by hydraulic barriers or buildings, and the impossibility to perform pumping tests) generate simulations able to reproduce the observed responses. The property and simulation maps generated make it possible to take into account the impact of the anthropic structures on the groundwater flows and to localize the parts of the hydraulic barriers where most exchanges between the channel and the aquifer occur.

Estimation of hydraulic parameters is important for the prediction of the future availability of groundwater reserves. Conventionally, pumping tests are conducted on boreholes to measure these parameters. However, such tests are costly and time consuming, and can only provide limited spatial information. An integrated approach of geophysical method and pumping tests is cost-effective and efficient alternative for the estimation of aquifer parameters. A geophysical method of vertical electrical sounding (VES) was carried out in Huizhou ADS site of China for the delineation of aquifer potential zones to assess the groundwater resources contained within the weathered rock. Initially, the pumping test data were used to determine the hydraulic parameters namely hydraulic conductivity (Kw) and transmissivity (Tw) for available production wells. Afterwards, one empirical relation between pumped hydraulic conductivity (Kw) and aquifer resistivity (ρa), and another between pumped transmissivity (Tw) and transverse resistance (Tr) were obtained to estimate hydraulic conductivity (K) and transmissivity (T) for all VES stations where pumping tests were not conducted. In this way, the entire study area was investigated to delineate the aquifer potential zones i.e., high potential aquifer zone with ρa 150 m2/day and K > 4 m/day, medium potential aquifer zone with ρa ranging from 100 to 150 Ωm, T from 100 to 150 m2/day and K from 3 to 4 m/day, poor potential aquifer zone with ρa from 150 to 300 Ωm, T from 50 to 100 m2/day and K from 2 to 3 m/day, and negligible potential aquifer zone with ρa > 300 Ωm, T < 50 m2/day and K < 2 m/day. This investigation also deciphers functional analogous relation of Ωa with K and Tr with T in Huizhou, China. Therefore, similar integrated approach can be used in any geological similar area where the aquifer properties are required for the management of groundwater reserves.

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

The present study has been undertaken to depict spatial distribution of different aquifer parameters in the eastern part of Kushtia district through a detailed hydrogeological survey. For this investigation, 119 lithologs and 92 pumping test data have been used. These data have been processed, analyzed, interpreted and krigged for the spatial assessment of the aquifer properties viz. transmissivity, hydraulic conductivity, hydraulic diffusivity, specific yield, radius of influence, and specific drawdown. It is seen from the investigation that the transmissivity and hydraulic conductivity values obtained from the pumping tests of the wells are varying from 1811 m2/day to 2568 m2/day and 32.5 m/day and 61.5 m/day respectively, the hydraulic diffusivity being ranging from 181,143 m2/day to 256,788 m2/day. The estimated specific yield of 17.97% - 23.46% supports that the area is dominated with coarse grained sands. This study reveals that the distribution of deep tube wells in the area are not within the radius of influence (638 - 760 m) each other, but few shallow and hand tube wells existed within the radius of influence. The estimated specific draw down is varying from 57 m/cumec to 126.1 m/cumec. From the overall analysis, it is found that the area is favorable for groundwater exploration.

Adequate estimates of aquifer properties are of utmost importance for proper management of groundwater resources. In an effort to provide alternative way of estimating aquifer properties at minimum...

The Precipice Sandstone is a major Great Artesian Basin aquifer in the Surat Basin, Queensland, Australia, which is used for water supply and production of oil and gas. This report describes use of observed groundwater pressure responses to managed aquifer recharge (MAR) at a regional scale to test recent geological descriptions of Precipice Sandstone extent, and to inform its hydrogeological conceptualisation. Since 2015, two MAR schemes have injected over 20 GL of treated water from coal seam gas production into the Precipice Sandstone, with pressure responses rapidly propagating over 100 km, indicating high aquifer diffusivity. Groundwater modelling of injection and inversion of pressure signals using PEST software shows the spatial variability of aquifer properties, and indicates that basin in-situ stresses and faulting exert control on permeability. Extremely high permeability, up to 200 m/day, occurs in heavily fractured regions with a dual-porosity flow regime. The broader-scale estimates of permeability approach an order of magnitude higher than previous studies, which has implications for the management of water resources in the Precipice Sandstone. Results also show the Precipice Sandstone to have broadly isotropic permeability. The results also support a recent geological interpretation of the Precipice Sandstone as having more limited lateral extent than initially considered. The study shows the effective use of MAR injection data to improve geological and hydrogeological understanding through groundwater model inversion. It also demonstrates the utility of combining hydrogeological and reservoir-engineer datasets in areas explored and developed for both groundwater resources and oil and gas resources.

Hydraulic properties of coastal, urban aquifers vary spatially and temporally with the complex dynamics of their hydrogeology and the heterogeneity of ocean-influenced hydraulic processes. Traditional aquifer characterisation methods are expensive, time-consuming and represent a snapshot in time. Tidal subsurface analysis (TSA) can passively characterise subsurface processes and establish hydro-geomechanical properties from groundwater head time-series but is typically applied to individual wells inland. Presented here, TSA is applied to a network of 116 groundwater boreholes to spatially characterise confinement and specific storage across a coastal aquifer at city-scale in Cardiff (UK) using a 23-year high-frequency time-series dataset. The dataset comprises Earth, atmospheric and oceanic signals, with the analysis conducted in the time domain, by calculating barometric response functions (BRFs), and in the frequency domain (TSA). By examining the damping and attenuation of groundwater response to ocean tides (OT) with distance from the coast/rivers, a multi-borehole comparison of TSA with BRF shows this combination of analyses facilitates disentangling the influence of tidal signals and estimation of spatially distributed aquifer properties for non-OT-influenced boreholes. The time-series analysed covers a period pre- and post-impoundment of Cardiff’s rivers by a barrage, revealing the consequent reduction in subsurface OT signal propagation post-construction. The results indicate that a much higher degree of confined conditions exist across the aquifer than previously thought (specific storage = 2.3 × 10−6 to 7.9 × 10−5 m−1), with implications for understanding aquifer recharge, and informing the best strategies for utilising groundwater and shallow geothermal resources.

International audience; Statistical analysis of a borehole database, linear discharges, and water strikes processing enabled an understanding of the structure, geometry and hydrodynamic properties of the metamorphic hard rock aquifers from the Montagnes District, Western Côte d’Ivoire. The database comprises 1654 boreholes among which 445 only were usable for this research work after its pre-processing. Analysis shows that the structure of the aquifer is similar to that observed in several other areas in the world: it developed due to weathering processes, comprises the capacitive saprolite, 10–20 m thick on average, and an underlying transmissive fractured layer, overlying the unweathered impermeable hard rock. The fractured layer is 80 m thick, the first 40 to 45 metres being its most productive zone, with a 11.3 m3/h median productivity. This research shows that metamorphic aquifers exhibit similar aquifer properties (thickness, hydrodynamic parameters) as plutonic ones and that there is interest in using such databases for research and other purposes. However, a rigorous pre-treatment of the data is mandatory, and geological data from published maps must be used instead of the geological data from the database. A previous methodology aiming at processing the boreholes’ linear discharges was improved. It notably appears that the slope method must be preferred to the percentile method.

One of the main factors for the urban sustainable development planning is the fresh water availability, especially in arid area such as Holy Makkah, Saudi Arabia. The area has most important religious places for the Islamic world, and thus, millions of visitors are coming to the city every year. Almost half of fresh water demands in the area are coming from the decreasing groundwater that are embodied in the wadi deposits and fractured crystalline rocks. However, the fresh water demands are rapidly increasing; therefore, the evaluation of the water resources along the area is strongly needed. Integrated geophysical methods to evaluate the subsurface situation and water content have been applied along Wadi Nu’man that is bounding the Holy area. Aeromagnetic and geoelectrical resistivity sounding measurements have been carried out along the wadi. Processing and modeling of the magnetic data indicated that the depth to the basement is irregular and controlled by the subsurface structure elements and the basement topography. The subsurface basement relief model indicated two local basins that undergo to keep the precipitated rainfall. Moreover, processing a suite of 155 vertical electrical soundings (VES) has been carried out along the wadi to determine the varying alluvial thickness covering the subsurface basement and the degree of water saturation. The processing and interpretation of VES data had been controlled by the subsurface lithological information of the available borehole as well as the magnetic data interpretation. Based on the output interpreted models, 2D cross sections have been constructed to emphasize the alluvial wadi deposits and the basement. Finally, the water budget along the wadi has been estimated using the results of geophysical and available metrological data sets. The estimated water stored in the subsurface wadi deposits and shallow fracture basement is around 56 million m3.

Characterizing aquifer properties and their associated uncertainty remains a fundamental challenge in hydrogeology. Recent studies demonstrate the use of oscillatory flow interference testing to characterize effective aquifer flow properties. These characterization efforts relate the relative amplitude and phase of an observation signal with a single frequency component to aquifer diffusivity and transmissivity. Here, we present a generalized workflow that relates extracted Fourier coefficients for observation signals with single and multiple frequency components to aquifer flow properties and their associated uncertainty. Through synthetic analytical modeling we show that multi-frequency oscillatory flow interference testing adds information that improves inversion performance and decreases parameter uncertainty. We show increased observation signal length, sampling frequency, and pressure sensor accuracy all produce decreased parameter uncertainty. This work represents the first attempt we are aware of to quantify effective aquifer parameters and their associated uncertainty using multi-frequency oscillatory flow interference testing.

The constant-rate pumping test (CRT) is commonly used to determine the aquifer properties. In this method, measured drawdown in the pumping well and the monitoring wells are usually matched with type curves developed by various analytical methods. However, numerous assumptions used to develop the analytical solution are not always compatible with the actual site conditions. In this study, drawdown records collected in a pumping well and two monitoring wells located near a river, were analyzed to investigate the boundary effects on the estimated aquifer properties. This site condition violates the assumption that the aquifer is of infinite areal extent. Moreover, time varying water heads during the pumping and recovery tests were simulated numerically to determine the effect of hydraulic gradient, which does not satisfy the assumption of horizontal potentiometric surface used in the analytical solution. Calibrated aquifer properties without the boundary effect showed clear differences, where the transmissivity, anisotropy ratio and specific yield varied by 12%, 34% and 53%, respectively, as compared to the results obtained by including the boundary effect. Numerical simulation conducted by considering a horizontal potentiometric surface as in the analytical model produced an averaged root-mean-squared-error (RMSE) of 0.055 m, which was approximately 57% higher than the RMSE value estimated with the effect of the hydraulic gradient. Therefore, it was concluded that the simplified analytical solutions may lead to misleading estimations of aquifer properties when the pumping test was conducted in an area with complex site conditions.

Seasonal variations of water temperature, electric conductivity, and oxygen isotope and chemical composition of shallow groundwaters and river waters were determined in the Sho River alluvial fan, western Toyama Prefecture, Japan, to examine groundwater heat utilization for indoor climate control. Samples were collected at 31 sites every 2 months for 1 year and at 11 representative sites monthly. In addition, the results of monthly precipitation amount and oxygen isotope composition of precipitation collected within the region during the same period were also taken into account. The sources of the shallow groundwaters are a mixture of river water and precipitation. The contribution of precipitation to groundwater is generally small along the Sho River but reaches as much as 80% along the Oyabe River and in the south and west of the alluvial fan. Though the origin of the groundwater differs regionally, water temperature is fixed at around 15 °C throughout the year in the northern part of the alluvial fan, and open-type ground source heat pump systems can be used for cooling and heating there, if adequate quantitative aquifer properties (exploitable groundwater amounts) are present.

Estimation of aquifer properties allows quantitative prediction of the hydraulic response of the aquifer to recharge and discharge. However, conventional methods such as pumping tests, among other limitations, are costly and time-consuming. Thus, this study aims to estimate hydraulic properties of basement aquifers of the Idi-Ishin area of Ibadan, southwest Nigeria using an indirect electrical resistivity technique. Sixty-two (62) vertical electrical soundings (VES) were carried out along eleven (11) E-W established traverse lines with a view to intercepts the fracture systems. The acquired resistivity data were subsequently interpreted using computer software, IP12WIN, for iteration and generated layered parameters. Layer parameters were further evaluated to derive the Dar–Zarrouk parameters such as longitudinal conductance (S) and transverse resistance (R) to estimate the aquifers transmissivity (T) and hydraulic conductivities (H). Pumping test was performed, and the hydraulic conductivities and transmissivities determined were correlated with the calculated values from the electrical sounding data. The subsurface geophysical investigation revealed three to four-layer systems; topsoil, weathered-partially weathered basement, fractured basement and fresh basement. The weathered-fractured basement at varied depths serves as shallow groundwater aquifers. The computed T and H ranged from 9.69 × 10–2 to 1.71 × 10–1 m2/day and 9.13 × 10–3 to 1.86 × 10–2 m/day which give a good relationship with the respective in-situ values from 2.46 to 6.15 × 10–1 m2/day and 1.88 × 10–2 to 4.70 × 10–3 m/day. S and R vary between 0.014 and 0.714 Ω−1 and 84.48–30,112.57 Ωm2, revealing a poor to good recharge and huge aquifer thickness. Also, longitudinal resistivity (LR) and transverse resistivity (TR) range from 12.3 to 242.7 Ωm−1 and 20,333.1–106.5 Ωm−1 an indicative of variation in the basement lithology as coefficient of anisotropy (λ) vary from 2.1 to 14.9, reflecting differences in basement characteristics for direction of fluid motion and accumulation. This study supports using electrical resistivities measurement to determine aquifer hydraulic conductivities, transmissivities, and protective capacity.

The crystalline-rock aquifer system of the Llano Uplift (Central Texas, USA) hosts an important local water resource that has been relatively little studied. The Uplift is a structural dome of Precambrian granitic and metamorphic rocks. Late Paleozoic normal faulting and fractures, decompressive fractures, weathering, lithology, and rock fabric control the aquifer properties. Data from driller reports (over 2,000 wells) show that wells in granites have higher median yields than wells in metamorphic rocks. There is a weak correlation of well yield with regolith thickness, and median regolith thickness is greater over granites than over metamorphic rocks. Fracture permeability, which is very heterogeneous, is the major control. Wells are shallow (generally

Aquifer strength is one of the main parameters in surface water separation facilities design. The material balance method is a common approach to calculate the aquifer strength and water influx in mature reservoirs which are in the second half of their lives. However, this method could not be used for green and newly developed reservoirs. In this type of reservoirs, the suitable vertically and laterally distance between aquifer and perforation intervals in the development wells is a main question which depends on future aquifer behavior. In this study, a methodology has been presented to estimate aquifer properties using water pressure data and also well testing data in a newly developed giant gas field in Middle East. The numerical sector model is used to match simulated water pressure data with actual MDT (Modular Dynamic Tester) data. The water relative permeability for each rock type and vertical-horizontal permeability relationship have been determined in history matching process. The tuned model can be used for the prediction of the aquifer performance and also the water production in future development wells.

Constant-rate pumping tests (CRPT) performed in aquifers having an inclined substratum (IS) cannot be interpreted using Theis-like models, due to an increasing thickness that is beyond conventional hydraulic assumptions. Using an empirical process based on numerical modelling, this study submits original tools for the detection of IS aquifers and the interpretation of their hydrodynamic responses to CRPT, using derivative [ds/dlog(t)] and flow dimension (n) analyses. It is shown that IS aquifers produce a drawdown log-derivative signal composed of two radial regimes and one spherical flow regime (n-sequence = 2–2–3). Comprehensive sensitivity analyses make it possible to constrain relationships between, on one hand, characteristic derivative responses, and on the other hand, hydraulic conditions such as pumping rate, distance from the well to the corner, substratum inclination, and aquifer properties, including anisotropic hydraulic conductivity. This study contributes to widening the array of tools available for the interpretation of pumping tests, by implementing a novel conceptual model for a specific type of nonuniform aquifer that has remained unaddressed; further, it provides another interpretation of the spherical flow regime, which has been interpreted in the petroleum literature to reflect partially penetrating/completing wells. Finally, a field application of the submitted interpretative tools to a CRPT into an IS aquifer is presented.

The population living in the foothills of Churia, the study area, faces severe water scarcity due to limited access to surface water. The only alternative is groundwater, and there is extensive use of groundwater for domestic and agricultural purposes. Groundwater in some areas is limited and very limited information pertaining to the aquifer. In this context, this research tries to answer the pertinent questions concerning the aquifer properties, depth and thickness of the groundwater aquifer layer and groundwater prospects for irrigation. The objective of this research is to identify the aquifer properties and groundwater prospects using two-dimensional electrical resistivity tomography methods (2D-ERT). Five 2D-ERT profiles were used to collect information to a depth of around 40 m, with minimum electrode spacing of 5 m over a profile length of 240 m. The survey was carried out using Wenner electrode configurations. The resistivity tomogram sections were interpreted using RES2DINV software, which provides output in the form of resistivity contours that are used to draw up the lithological and geological information. The result of the survey indicates that the areas with good potential for groundwater access exist mostly along the southeast to central east parts of the study area, where there is gravel and sand with resistivity values between 100 and 500 Ω m. Areas along the northwest with clay and silty clay formations have low resistivity values ( 2000 Ω m) due to sand formation underlain by boulder and cobbles, it also has limited groundwater potential due to the limited depth (

Distributed temperature sensing is known to provide sharp signals which are very efficient for mapping hydraulically active fractures in wellbores. High-resolution temperature sensing has specifically demonstrated its capacity to characterize very low flows in wellbores. But as sharp as they can be, temperature profiles are often difficult to decipher. The aim of the present work is to provide and to test the “Borehole Heat Budget Calculator” (BHB Calculator), which is implemented as a fast and easy to use tool for the quantitative analysis of depth-temperature profiles. The Calculator is suitable for most pumping and draining configurations, as the heat budget is generalized for modelling multidirectional flow systems within the same wellbore. The formatted worksheet allows the quick exploitation of temperature logs, and is applicable for the characterization of distributed fractures in long screened wellbores. Objectives of the heat modelling are to enhance the readability of complex depth-temperature data, as well as to quantify distribution of inflow intensities and temperatures with depth. The use of heat budget helps to clearly visualize how heat conduction and heat advection contributions are distributed along wellbores profiles. Calculations of inflow temperatures and their evolution through pumping duration is a prerequisite to infer about the nature of aquifer properties (i.e. conduits, distributed or discrete fractures, porous media), as well as to give insight information about the mapping of effective flow paths draining the aquifer. The efficiency and limitations of the BHB Calculator are being tested through high-resolution temperature logging, along with complementary flowmetering and televiewing logging in fractured aquifers located in the St-Lawrence Lowlands, Quebec, Canada.

Resistivity data constitute the largest part of the available information to assess the hydrogeological characteristics of the aquifer system near Oruro, in the central part of the Bolivian Altiplano. Two aquifers are part of this system; top unconsolidated sediments storing fresh water in their granular voids, overlying fractured hard rock formations where saline water was detected in connection to some faults. This study proposes an indirect and cost-effective way to estimate aquifer hydraulic properties for the groundwater management in the region. Hydraulic conductivity and transmissivity in the top aquifer were estimated using an empirical linear relationship between hydraulic conductivity and resistivity. This latter parameter, as well as the aquifer thickness, were obtained from the inverted models corresponding to the geoelectrical tests performed in the study area (electrical resistivity tomography, transient electromagnetic soundings and vertical electrical soundings). The highest estimated transmissivity values are ∼4.0 × 10−2 m2/s located in the centre of the study area, the lowest values are ∼3.4 × 10−3 m2/s, located around thermal intrusions to the south and where the top of the bedrock is shallow (∼20 m depth) to the west. The methodology presented in this study makes wider use of resistivity measurements to identify promising groundwater production sites.

Hard rocks, including crystalline igneous, metamorphic and strongly cemented sedimentary and carbonate rocks, cover about 50% of the Earth's land surface (Singhal & Gupta 2010). Globally, the volume of groundwater contained in hard rock aquifers is not well constrained (Comte et al. 2012) but locally they can be important aquifers (MacDonald et al. 2012), albeit with low groundwater storage and poor primary porosity and permeability. Groundwater flow in these hard rocks is commonly observed to be associated with water-bearing discontinuities, such as fractures, joints and faults (Mazurek 2000; Berkowitz 2002; Font-Capo et al. 2012), and in the weathered regolith (Wright 1992; Chilton & Foster 1995; Deyassa et al. 2014). Structural elements such as fault zones also strongly govern the behaviour of these systems (Forster & Evans 1991; Lopez & Smith 1995; Bense et al. 2013). The nature, abundance, orientation and connectivity of these water-bearing features are largely governed by the history and nature of structural deformation of the bedrock, and commonly impose strong anisotropic flow and transport parameters on these bedrock aquifers (Hsieh et al. 1985; Bour & Davy 1997; Mortimer et al. 2011). Weathering processes furthermore lead to an alteration of bedrock composition and associated aquifer properties resulting in enhanced fracture connectivity and an overall vertical stratification/zonation of bulk aquifer properties, ranging from highly altered shallow regolith horizons to more competent sparsely fractured bedrock at depth (Dewandel et al. 2006; Krasný & Sharp 2007; Lachassagne et al. 2011).

Connectivity of groundwater flow within crystalline-rock aquifers controls the sustainability of abstraction and baseflow to rivers, yet is often poorly constrained at a catchment scale. Here groundwater connectivity in a sheared gneiss aquifer is investigated by studying the intensively abstracted Berambadi catchment (84 km2) in the Cauvery River Basin, southern India, with geological characterisation, aquifer properties testing, hydrograph analysis, hydrochemical tracers and a numerical groundwater flow model. The study indicates a well-connected system, both laterally and vertically, that has evolved with high abstraction from a laterally to a vertically dominated flow system. Likely as a result of shearing, a high degree of lateral connectivity remains at low groundwater levels. Because of their low storage and logarithmic reduction in hydraulic conductivity with depth, crystalline-rock aquifers in environments such as this, with high abstraction and variable seasonal recharge, constitute a highly variable water resource, meaning farmers must adapt to varying water availability. Importantly, this study indicates that abstraction is reducing baseflow to the river, which, if also occurring in other similar catchments, will have implications downstream in the Cauvery River Basin.

Tidal analysis provides a cost-effective way of estimating aquifer properties. Tidal response models that link aquifer properties with tidal signal characteristics, such as phase and amplitude, hav...

High temperature aquifer thermal energy storage (HT-ATES) can play a key role for a sustainable interplay between different energy sources and in the overall reduction of CO2emission. In this study, we numerically investigate the thermo-hydraulic processes of an HT-ATES in the Greater Geneva Basin (Switzerland). The main objective is to investigate how to handle the yearly excess of heat produced by a nearby waste-to-energy plant. We consider potential aquifers located in different stratigraphic units and design the model from available geological and geophysical data. Aquifer properties, flow conditions and well strategies are successively tested to evaluate their influence on the HT-ATES economic performance and environmental impact. This was achieved using a new open-access, user-friendly and efficient code that we also introduce here as a possible tool for geothermal applications. The results highlight the importance of thorough numerical simulations based on more realistic exploitation when designing HT-ATES systems. We show that relations between thermal performance and the shape of the injected thermal volume are generally hard to derive when complex well schedules are imposed because the injected/produced volumes may not be equal. Despite more complex storage strategies to comply with legal regulations, the shallower group of investigated aquifers in this study remains economically more suitable for storage up to 90ºC. In average four well doublets will be required to store the yearly excess of energy. The deeper group of investigated aquifers, however, become interesting for storage at higher temperatures.

In a recent paper (Trefry et al., 2019) we showed that the interplay of aquifer heterogeneity and poroelasticity can produce complex transport in tidally forced aquifers, with significant implications for solute transport, mixing and reaction. However, what was unknown was how broadly these transport dynamics can arise in natural groundwater systems, and how these dynamics depend upon the aquifer properties, tidal and regional flow characteristics. In this study we answer these questions through parametric studies of these governing properties. We uncover the mechanisms that govern complex transport dynamics and the bifurcations between transport structures with changes in the governing parameters, and we determine the propensity for complex dynamics to occur in natural aquifer systems. These results clearly demonstrate that complex transport structures and dynamics may arise in natural tidally forced aquifers around the world, producing solute transport and mixing behaviour that is very different to that of the conventional Darcy flow picture. Key Points: * Transient Darcy flows can generate complex transport dynamics in heterogeneous compressible aquifers. * This complex transport can trap dispersing solutes for many years. * Global tidal maps indicate widespread potential for complex transport dynamics in coastal zones., Comment: 54 pages, 17 figures, including supporting material

Aquifer parameters (e.g. hydraulic conductivity and transmissivity) are routinely determined from pumping tests. Pumping tests are very expensive and researchers have continued to explore cheaper and reliable alternatives to determine these parameters at locations without producing wells. Electrical resistivity method was applied to determine hydraulic conductivity and transmissivity in areas without boreholes in the present study area. Fifteen (15) vertical electrical soundings with a maximum current electrode spacing of 300 m, in the Schlumberger configuration, were acquired. Seven (7) of the soundings were carried out near existing boreholes for comparative analysis between geologic and geoelectric sections. Modelling was done using the IPI2™ software. Cross-plot of hydraulic conductivity (K) obtained from pumping tests and aquifer resistivity (ρ) extracted from sounding interpretations was used to generate a linear relation of the form K = 0.0426ρ + 0.8584. A similar cross-plot between transmissivity (T) and transverse resistance (R) gave another linear relation of the form T = 31.92–0.0019R. These relations, which connects geoelectrical properties with aquifer hydraulic properties, were used to estimate aquifer properties in areas away from well locations. Results show that depth to water ranges from 11.5 m at Mgbom to 52.1 m at Immama Ozizza, while aquifer thickness varies from 14 m at Poperi Primary School, Amasiri (VES 1) to 47.6 m at Immama Ozizza (VES 11). Hydraulic conductivity values range from 1.344 m/day at Mgbom (VES 2) and 2.792 m/day at Okpotokun Primary School Amata-Akpoha (VES 15), with a mean of 2.068 m/day. Transmissivity on the other hand varies between 28.18m2/day at Immama Ozizza (VES 11) and 31.73 m2/day at Mgbom (VES 2) with a mean of 29.96 m2/day. The derived results correlates well with those obtained from pumping test analysis and have provided a cost-effective method for estimating aquifer hydraulic parameters in areas away from well locations.

Hydrochemical characteristics and aquifer properties present a better understanding of the mitigation of groundwater pollution, which has become one of the leading environmental concerns and threats to the sustainable ecosystem. Seventy-seven groundwater samples were collected from Sargodha District (Pakistan) and characterized for their physical and chemical properties. The analytical data were processed for the evaluation of the processes that control the groundwater chemistry using various drinking and agricultural indices with statistical and hydrochemical modeling. The predominant hydrochemical type was found to be Ca-HCO3 type, followed by Na-HCO3 and Mg-Ca-Cl types. The present study showed that the main factors controlling the groundwater chemistry were the prevalent rock dominance alongside the weathering of silicates, solubilization of carbonates, and cation exchange processes. Entropy water quality index (EWQI) revealed that 6.51% represented “poor water,” while 7.79% were considered “extremely poor” for drinking purposes. However, USSL classification, Wilcox diagram, and other agricultural indices (RCS, SAR, %Na, MH, PI, and PS) showed that the majority of the samples were classified as suitable for irrigation purpose. However, 16% of the samples for %Na and 24% of the samples for MH were not suitable for agricultural purposes. Overall, the groundwater quality was affected by the anthropogenic stress in the study area.

Quaternary palaeo-environmental changes that have taken place in Croatia are likely to be recorded in speleothems – secondary carbonate deposits precipitated in caves. Confident interpretation of well dated speleothem proxy records relies on modern monitoring programs, which we provided in three regionally different caves. Parallel monitoring of the surface and cave air temperature and relative humidity, precipitation and cave drip intensity, as well as stable isotope modification of meteoric and drip water was carried out in order to estimate the most reliable stalagmites for the interpretation of Quaternary landscape history. In all three caves, Nova Grgosova (239 m a.s.l.; T cave = 11.2 °C) in central Croatia, Lokvarka (780 m a.s.l.; T cave = 7.5 °C) in the mountainous part of Croatia, and Modric (32 m a.s.l.; T cave = 16.6 °C) in coastal Croatia, we selected the parts of the caves where the ambient cave conditions appeared to be appropriate for equilibrium deposition of calcite in terms of constant air temperature (seasonal amplitudes of 0.73, 0.38 and 0.45 °C, respectively) and relative humidity (100%). Both Atlantic and Mediterranean moisture influences were detected in all three caves, but of different intensities. Cave hydrological settings governed by karst aquifer properties were resolved by the comparison of the precipitation intensities and drip site responses to the rain events, and generally, seasonal rainwater isotopic signal was almost completely attenuated, except for one drip site. Such homogenized drip water and stable cave environmental settings give confidence for calcite deposition under equilibrium conditions, especially for Modric and Nova Grgosova caves where speleothems' inner structures also look promising for potentially quality dating results and stable isotopic profiles. The fracture-flow drip regime of selected drip sites in Lokvarka Cave, and uncompleted homogenization of the water in the epikarst might point to speleothem samples that are unsuitable for resolving multi-annual Quaternary climate changes. This view is supported by the high porosity internal structure of some Lokvarka speleothems, so further monitoring, sampling and the thorough speleothem examination is therefore necessary for adequate interpretations of palaeo-environmental changes.

The paper presents the results of a preliminary study of geology and hydrogeological conditions of a Grudziądz groundwater intake. The focus of the study was to develop a conceptual model that will be used in further investigation to create a hydrogeological model. In the intake area two multi-aquifer formations have been distinguished: Quaternary and Paleocene-Cretaceous. The Quartenary multi-aquifer formation, which consists of two aquifers separated by poorly permeable rocks, is primary utility. Groundwater in the Paleocene-Cretaceous aquifer has an elevated mineral content, which makes it not usable. The intake is located near Grudziądz and areas of intense farming, which leads to a hazard of anthropopressure, and may have a negative impact on the groundwater quality and quantity. In-office work conducted for the preparation of article included gathering and description of archival data from over 120 years of intake existence. Data from 53 hydrogeological boreholes have been analyzed. In 2017, field work was also conducted, including several measurements of water table in wells and piezometers of the intake. Water samples have also been collected for chemical analyses. An efficiency assessment of some observation wells has been made, establishing their hydrogeological parameters using the PARAMEX method.

Weathered crystalline bedrock aquifers sustain water supplies across the tropics, including East Africa. Although well yields are commonly

The hydrograph recession curve expresses the theoretical relationship between the aquifer structure and the flow of groundwater flowing into the river basin channel. These theoretical relationships are often empirically depicted using the base flow recession curve. The hydrograph recession curve is commonly used to estimate the recessionary parameters, aquifer properties and to evaluate alternative hydrological hypotheses. The river basin hydrograph recession curve records the behavior of the relationship between the aquifer structure and its association with groundwater outflow to the river channel. This research was conducted with the aim: to analyze the characteristics of the baseflow recession based on the parameters and coefficients of the recession, and the shape of the individual recession curve and the master recession curve. The characteristics of the baseflow recession to research sub-watershed have the recession curves tend to sloped, describing the water storage well enough. The parameter Q0 (recession early), α and the recession constant Krb ranging from 0,80 – 0,90 for the individual and master recession curve in all three research sub-watershed. This calculation result indicates that the recession characteristics in three research sub-watershed have the condition of water storage is excellent, because they are supported by the aquifer characteristics dominated by the geological structures are more permeable (porous).

The Pilbara region is one of the most important mining hubs in Australia. It is also a region characterised by an extreme climate, featuring environmental assets of national significance, and considered a valued land by indigenous people. Given the arid conditions, surface water is scarce, shows large variability, and is an unreliable source of water for drinking and industrial/mining purposes. In such conditions, groundwater has become a strategic resource in the Pilbara region. To date, however, an integrated regional characterization and conceptualization of the occurrence of groundwater resources in this region were missing. This article addresses this gap by integrating disperse knowledge, collating available data on aquifer properties, by reviewing groundwater systems (aquifer types) present in the region and identifying their potential, and proposing conceptualizations for the occurrence and functioning of the groundwater systems identified. Results show that aquifers across the Pilbara Region vary substantially and can be classified in seven main types: coastal alluvial systems, concealed channel iron deposits, inland valley-fill aquifers, karstified dolomites, sandstone aquifers (West Canning Basin), Permian/Cenozoic Paleochannels, and Fractured Rock aquifers. Coastal alluvial systems show the greatest regional potential as water sources and are currently intensively utilised. Conceptually, the main recharge processes are infiltration of precipitation associated with cyclonic events and the interaction with streamflows during summer season, whereas the main discharge mechanisms correspond to evapotranspiration from riverine and coastal vegetation, discharge into the Indian Ocean, and dewatering of iron-ore bodies to facilitate mining activities. Important gaps in the knowledge relate to aquifer connectivity and accurate quantification of recharge/discharge mechanisms.

Groundwater pathways and residence times are controlled by aquifer flow and storage properties, which, in weathered/fractured hard rock aquifers, are characterized by high spatial heterogeneity. Building on earlier work in a metamorphic aquifer in NW Ireland, new clay mineralogy and analyses of geophysical data provided high spatial resolution constraints on the variations in aquifer properties. Groundwater storage values derived from magnetic resonance sounding and electrical resistivity tomography were found to largely vary laterally and with depth, by orders of magnitude. The subsequent implementation of hillslope, two-dimensional numerical groundwater models showed that incorporating heterogeneity from geophysical data in model parametrization led to the best fit to observations compared with a reference model based on borehole data alone. Model simulations further revealed that (1) strong spatial heterogeneity produces deeper, longer groundwater flow paths and higher age mixing, in agreement with the mixed sub-modern/modern ages (mostly

Past studies modeling stream-aquifer interaction commonly account for vertical anisotropy in hydraulic conductivity, but rarely address horizontal anisotropy, which may exist in certain sedimentary environments. If present, horizontal anisotropy will greatly impact stream depletion and the amount of recharge a pumped aquifer captures from the river. This scenario requires a different and somewhat more sophisticated mathematical approach to model and interpret pumping test results than previous models used to describe captured recharge from rivers. In this study, a new mathematical model is developed to describe the spatiotemporal distribution of drawdown from stream-bank pumping with a well screened across a horizontally anisotropic, confined aquifer, laterally bounded by a river. This new model is used to estimate four aquifer parameters including the magnitude and directions of major and minor principal transmissivities and storativity based on the observed drawdown-time curves within a minimum of three non-collinear observation wells. In order to approve the efficacy of the new model, a MATLAB script file is programmed to conduct a four-parameter inversion to estimate the four parameters of concern. By comparing the results of analytical and numerical inversions, the accuracy of estimated results from both inversions is acceptable, but the MATLAB program sometimes becomes problematic because of the difficulty of separating the local minima from the global minima. It appears that the new analytical model of this study is applicable and robust in estimating parameter values for a horizontally anisotropic aquifer laterally bounded by a stream. Besides that, the new model calculates stream depletion rate as a function of stream-bank pumping. Unique to horizontally anisotropic and homogeneous aquifers, the stream depletion rate at any given pumping rate depends closely on the horizontal anisotropy ratio and the direction of the principle transmissivities relative to the stream-bank.

Two simple frequency decomposition techniques were used as part of a tidal response method to derive the hydraulic diffusivities of a freshwater-lens aquifer. Digital high-pass filtering can separate the tidal components of diurnal and shorter periods from longer-period components. Discrete Fourier transform can be used to isolate a specific tidal component. These techniques are easy to practice using the built-in functions of spreadsheet software. The applied techniques were each optimized for the frequencies of known major tidal components. Isolation of the specific tidal signals helps to reduce the errors of a basic tidal response method that uses in its calculations the amplitude attenuation and phase lag of a simple sinusoidal wave of groundwater fluctuations. Another advantage of the present tidal method is the utilization of two groundwater time series collected from near-shore and relatively inland sites affected by the same ocean tide. The method does not use surface-water observation, thus avoiding errors derived from generally possible surface-water/groundwater boundary effects.The tidal response method with simple decomposition techniques was used to investigate the aquifer properties of an uplifted limestone island located in a subtropical region of Japan. A freshwater lens is the principal water resource for this island and its sustainable development is desired. Significant hydraulic layering has not been reported in the limestone aquifer. Pairs of groundwater-level time-series data collected by simultaneous observations at near-shore and inland sites were analysed by the tidal response method. The results demonstrated heterogeneous aquifer diffusivity on the island, typically with larger values in the southeastern coastal part than in the northwestern coastal part, which is consistent with the planar distribution of the entire freshwater lens and the position of its maximum thickness that are slightly biased toward the northwestern side.

The relevance of the work is conditioned by the need to use random processes based on Levi-distribution in describing the process of filtration of fluid flow in oil reservoirs and groundwater. These processes describe the filtration process more accurately than the fractal Brownian motion (fBm) and fractal Gaussian noise (fGn), especially with sharp changes in the geological environment. The purpose of the work is to show the advantages of using stochastic interpolation methods in geostatistics as compared to deterministic methods (in particular, the creaking method). Research methodology: theoretical analysis and experimental study of methods for probabilistic modeling of aquifer properties of geological media under conditions of uncertainty and limited availability of information on permeability and porosity of reservoirs. Results. It is shown that stochastic interpolation is most suitable for modeling dispersion characteristics of heterogeneous geological formations. The use of the assumption of Gaussian distribution in describing the process of fluid filtration is unreasonable. It is especially unreasonable in the presence of abrupt changes inherent in geological stratifications. Such changes are more adequately described by fractal Levi-motion (fLm). Stable Levidistribution of increments of the studied filtration characteristics of oil-saturated deposits showed a good coincidence with empirical data of numerous physical changes of geological structures in a wide range of spatial variables vertically and horizontally. Conclusions. The use of fLm – models represents a fundamentally new approach in geostatistics. The presence of heavy tails of the Levi-distribution of increments of the filtration characteristics of the layers and scaling the distribution parameters of this distribution allows us to react to sudden and sharp changes in rock properties. This effectively reproduces the strata and sedimentary deposits on the reservoir surface and characterizes heterogeneity in a wide range of distribution of spatial variables.

Ocean surges cause seawater inundation of coastal inland areas. Subsequently, seawater infiltrates into coastal aquifers and threatens the fresh groundwater resource. The severity of resulting salinization can be affected by hydrogeological factors including aquifer properties and hydrologic conditions, however, little research has been done to assess these effects. To understand the impacts of hydrogeological factors on groundwater salinization, we numerically simulated an ocean-surge inundation event on a two-dimensional conceptual coastal aquifer using a coupled surface-subsurface approach. We varied model permeability (including anisotropy), inland hydraulic gradient, and recharge rate. Three salinization-assessment indicators were developed, based on flushing time, depth of salt penetration, and a combination of the two, weighted flushing time, with which the impact of hydrogeological factors on groundwater vulnerability to salinization were quantitatively assessed. The vulnerability of coastal aquifers increases with increasing isotropic permeability. Low horizontal permeability (kx) and high vertical permeability (kz) lead to high aquifer vulnerability, and high kx and low kz lead to low aquifer vulnerability. Vulnerability decreases with increasing groundwater hydraulic gradient and increasing recharge rate. Additionally, coastal aquifers with a low recharge rate (R ≤ 300 mm yr − 1 ) may be highly vulnerable to ocean-surge inundation. This study shows how the newly introduced indicators can be used to quantitatively assess coastal aquifer vulnerability. The results are important for global vulnerability assessment of coastal aquifers to ocean-surge inundation.

Study Region Rocky Mountains, United States Study Focus Groundwater-flow modeling requires estimates of hydraulic properties, namely hydraulic conductivity. Hydraulic conductivity values commonly vary over orders of magnitudes however and estimation may require extensive field campaigns applying slug or pumping tests. As an alternative, specific-capacity tests can be used to estimate hydraulic properties for large areas when benchmarked with slug or pumping tests. This study combined aquifer testing with specific capacity data to estimate hydraulic properties in a large alluvial aquifer. New hydrological insights for region In the Wet Mountain Valley, Colorado, both slug tests and pumping tests were conducted, resulting in a likely range of hydraulic-conductivity values. Aquifer-testing results were related to specific-capacity data, a more spatially distributed dataset, to expand the area of aquifer characterization beyond the distribution of wells included in aquifer testing. Specific-capacity data were used in two ways: (1) a regression was built between specific-capacity values and transmissivity derived from aquifer testing; and (2) an iterative method was utilized to estimate transmissivity from specific capacity at all sites (including sites lacking aquifer tests). Study results indicate that there is a statistically significant difference between hydraulic-conductivity values estimated using the two approaches and that the regression method yields systematically greater values. These results indicate that careful consideration of methods that use specific capacity for extrapolating aquifer properties is warranted as bias could be introduced depending on the applied methodology.

Aquifer Thermal Energy Storage (ATES) uses excess thermal energy to heat water which is stored in an aquifer until it is needed, at which time the hot water is recovered and the heat used for some purpose e.g. electricity generation. The recovery efficiency (i.e. the ratio of heat energy recovered to heat energy injected, R ) is one of the most important factors dictating the viability of ATES systems. The variation of R with various aquifer properties and operating parameters is explored for high temperature (HT) ATES systems with injection temperatures ≥ 90 ∘ C , extending the results of previous studies to higher temperatures and a broader range of aquifer properties and operating conditions. R values are calculated using numerical models of a single-well ATES system, which is validated by comparison with previous field and modelling studies. The results show that HT-ATES may be viable with injection temperatures as high as 300 ∘ C , depending on the aquifer properties and operating parameters. Daily cycles are very efficient over a broad range of conditions, whereas the efficiency of annual cycles is much more variable. The most important parameters governing R are aquifer thickness, injection temperature, horizontal and vertical permeability, and dispersion length. The R values are used to derive an improved version of the Rayleigh number relationship proposed by Schout et al. (2014), extending the applicability of this relationship to daily cycles and improving its accuracy for annual cycles. An alternative method for estimating R using a convolutional neural network is proposed. The calculated R values may be considered best-case because aspects such as background groundwater flow and geochemical effects are ignored. Practical factors such as energy supply/demand requirements, reservoir and above-ground engineering, financial or regulatory aspects, and public acceptance are not considered. Nevertheless, the results of this study can be used for rapid screening of large areas for potential HT-ATES sites, defining requirements for potential sites, and estimating R values for specific sites, before performing detailed feasibility studies.

Groundwater is extremely important in a water-scarce country such as Saudi Arabia, where permanent surface water resources are absent. Sustainable and future developments plans are essentially relying on the clear understanding of water resources. To evaluate the water resources in arid countries, the groundwater should be quantified through either traditional or scientifically advanced techniques. Aquifer characteristics, particularly the hydraulic conductivity and transmissivity, are essential for the evaluation the aquifer properties as well as the management and development of groundwater modelling for specific aquifers. The present study aims to evaluate the sub-basaltic alluvial aquifer in the northern part of Harrat Rahat, south of Al-Madinah city, and then estimates the principal aquifer’s hydraulic parameters based on the interpreted 1D resistivity-depth models along the study area. For that, 49 Vertical Electrical Soundings (VES’s) utilizing a Schlumberger electrode array were performed along the southern part of Al-Madinah city. The resistivity of the water-bearing formation, thickness, porosity, hydraulic conductivity, and transmissivity parameters were calculated along the measured longitudinal profile from the interpreted VES data. The estimated porosity, hydraulic conductivity, and transmissivity were achieved along the whole profile with average values of 0.2, 3.5 m/day, and 369.6 m2/day, respectively. The resulting transmissivity values from the VES models were compared with those of previous pumping test measurements carried out in the area and a reasonable correlation between the two data sets was observed. These results indicate that surface geoelectrical resistivity techniques may provide an alternative, rapid, and cost-effective method of estimating the aquifer hydraulic parameters where pumping data is rare or unavailable.

This communication represents the application of geoelectrical signatures such as Dar-Zarrouk parameters, namely longitudinal conductance (S) and transverse resistance (T), which play a vital role in deciphering subsurface geometry and detect water-bearing zones in hard rock area. A micro-watershed is situated in granite terrain of Southern India, where the variation of bedrock depth and location of water-bearing zones are identified using these signatures, and achieved from the results of 47 Vertical Electrical Soundings (VESs) data. Pumping wells are recommended for the drilling, and the high yielded wells are confirmed in the water-bearing zones. The observed borehole lithology is very closely correlated with the interpreted geoelectric layer parameters. It indicates that the water-bearing zones exit in highly weathered zones having a resistivity range of 50–100 Ω-m, and 100–300 Ω-m in fractured granites at 12 to 22 m depths. The estimated T and S-values reveal the conductive mediums within the host granitic rock, whereas low S and comparatively high T might be indicative possible water-bearing/shear zone. The aquifer properties at the selective wells are compared to the aquifer potentiality. The high permeability values have been observed to confirm the presence of a shear zone, which is more productive for providing a good yielding bore well. Therefore, this approach could be replicated for groundwater exploration in any hard rock terrain.

Buried bedrock valley aquifers are common across Canada, where multiple glaciations have buried both pre-glacial and Pleistocene valleys. These aquifers are becoming increasingly important as a supply of potable groundwater, for supporting aquatic habitat, and as part of strategies in adapting to a changing climate. However, in Canada, there are considerable knowledge gaps at national, regional, and local scales, such that many buried bedrock valleys remain unidentified or underexplored. Cape Breton Island provides a hydrogeological view into the roots of an ancient mountain range, now exhumed, glaciated, deglaciated, and tectonically inactive. Since the Cretaceous, a variety of geological processes have formed several buried bedrock valley aquifers over the island. These aquifers are important in providing municipal and commercial groundwater supplies, controlling mine dewatering, protection of salmonids, design and monitoring of waste disposal sites, and geotechnical investigations for infrastructure design. Of 150 sites assessed, 61% provided evidence of buried aquifers comprising unconsolidated sand and gravel of Cretaceous, Pleistocene, and Holocene ages. These sites provided the basis for five conceptual, 3-D hydrogeological block models. Three hydrogeological case studies provided further insight into the functioning of two of these models. Future studies should identify and characterize aquifers in high demand areas and/or those that support important riverine ecosystems. Research should focus on aquifer properties, groundwater-stream interaction, and the impact of changing climate with sea-level rise.

In recent decades, high groundwater extraction rates, often coincident with periods of severe drought, result in the widespread decline of water levels. Overexploitation of aquifers also causes land subsidence, which poses a severe threat to infrastructure. Tucson, Arizona experiences land subsidence coupled with the depletion of groundwater, a critical water resource for the desert city. To understand the spatiotemporal evolution of land subsidence and its implications for aquifer properties, we examine long time series of surface deformation and head levels. Measurements at extensometer stations indicate rapid compaction of fine-grained material up to 8.5 mm/yr from 1990 to 2005, which results in permanent storage volume losses up to 4.1%. The analysis of densely populated sets of interferograms generated from Envisat and RadarSAT C-band acquisitions yields multitemporal maps of surface deformation at unprecedented resolution. These maps reveal that subsidence significantly slows by the late 2000s, corresponding with the implementation of artificial recharge efforts. Subsequent to groundwater level recovery, we observe a brief 6.6-year interval of residual compaction, suggesting a high vertical hydraulic conductivity, which is then shown to be up to 9.8x10-4 m/day. We also estimate the average elastic and inelastic skeletal storage coefficients for the aquifer system to be 3.78x10-3 and 6.01x10-3, respectively. InSAR shows deformation nearly ceases by 2015, likely reducing hazards associated with earth fissuring and infrastructure damage. This study highlights successful outcomes of water management and conservation plans that preserve existing groundwater reserves and increase artificial recharge.

In a natural aquifer, the aquifer properties are complicated, which normally vary with aquifer depth and geographic characteristics. Most previous studies have been limited to the case of isotropic aquifer with uniform characteristics. In the proposed model, the fully coupled ground water flow and land deformation due to groundwater pumping in cross-anisotropic aquifer system is used to analyze and predict. Based on this model, pumping-recovery tests in various conditions are numerically simulated to reveal the effects of cross-anisotropic aquifer behavior on hydraulic head and land deformation. Finally, the proposed method is applied to a project in Shanghai of China due to pumping of groundwater predicted. Comparing the calculated results with the measured field values indicates that the methods can be a useful tool for designing groundwater pumping projects.

Groundwater resources management requires operational, regional-scale groundwater models accounting for dominant spatial variability of aquifer properties and spatiotemporal variability of groundwater recharge. We test the Ensemble Kalman filter (EnKF) to estimate transient hydraulic heads and groundwater recharge, as well as the hydraulic conductivity and specific-yield distributions of a virtual phreatic aquifer. To speed up computation time, we use a coarsened spatial grid in the filter simulations, and reconstruct head measurements at observation points by a local model in the vicinity of the piezometer as part of the observation operator. We show that the EnKF can adequately estimate both the mean and spatial patterns of hydraulic conductivity when assimilating daily values of hydraulic heads from a highly variable initial sample. The filter can also estimate temporally variable recharge to a satisfactory level, as long as the ensemble size is large enough. Constraining the parameters on concentrations of groundwater-age tracers (here: tritium) and transient hydraulic-head observations cannot reasonably be done by the EnKF because the concentrations depend on the recharge history over longer times while the head observations have much shorter temporal support. We thus use a different method, the Kalman Ensemble Generator (KEG), to precondition the initial ensemble of the EnKF on the groundwater-age tracer data and time-averaged hydraulic-head values. The preconditioned initial ensemble exhibits a smaller spread as well as improved means and spatial patterns. The preconditioning improves the EnKF particularly for smaller ensemble sizes, allowing operational data assimilation with reduced computational effort. In a validation scenario of delineating groundwater protection zones, the preconditioned filter performs clearly better than the filter using the original initial ensemble.