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In arid and semi-arid regions, groundwater is considered being the most available natural resources for different water use. However, it is being limited in quantity. As such, its sustainable development and managementent depends on based on various criteria (e.g. climatic conditions, scale, aquifer properties, etc.). This study presents three multi-criteria index approaches (Analytic Hierarchy Process (AHP), Best–Worst Method (BWM), and Full Consistency Method (FUCOM) to classify groundwater potential maps in the Sarakhs Plain in North-east Iran. In this study, 10 parameters (layers) that affect groundwater potential recharge mapping (GPRM) are used using ArcGIS10.2. These layers includeground surface elevation, surface slope, aspect, relative slope position (RSP), plan curvature, topographic wetness index (TWI), terrain ruggedness index (TRI), drainage density, landuse, and lithology. These layers and their features were assigned properweights based on the conceptual frameworks of AHP, BWM, and FUCOM techniques, and then using a weighted overlay summation process (WOSP), final maps of groundwater potential in Sarakhs plain are obtained. The developed groundwater potential maps are classified into four classes, including low, medium, high, and very-high. The results show that among the 10 driving parameters, land use, and lithology have the highest importance and the surface slope has the lowest importance in the mapping of groundwater potential recharge. The best groundwater potential zones are concentrated in northeast and southeast, central parts, and a few parts in the areas of the western regionof the Sarakhs plain due to its nearly gentle slopes with quaternary alluvial and agriculture land and lower drainage density. The obtained results are of high value for decision-makers in the Sarakhs plain in specific and for entire Iran in general to apply sustainable groundwater utilization plans.

The purpose of this research work is to comparatively study the oil recovery factor from two major aquifer geometry (Bottom and Edge water aquifer) using water aquifer model owing to the fact that most if not every reservoir is bounded by a water aquifer with relative size content (Most Large). These aquifers are pivotal in oil recovery factor (percent%), Cumulative oil produced (MMSTB) as well as overall reservoir performance the methodology utilized in this study involves; Identification of appropriate influx models were utilized for aquifer characterization. The characterizes of the Niger Delta reservoir aquifer considered include aquifer permeability, aquifer porosity etc. Estimation of aquifer properties is achieved by using regressed method in Material Balance Software (MBAL). This approach involves History Matching of average reservoir pressure with computed pressure of the reservoir utilizing production data and PVT data. The computed pressure from model is history matched by regressing most uncertain parameters in aquifer such as aquifer size, permeability, and porosity. Historic production data was imputed into the MBAL Tank Model, the production data was matched with the model simulation by regressing on rock and fluid parameters with high uncertainty. The match parameters were recorded as the base parameter and other sensitivity on aquifer parameters using the Fetkovich model for the bottom and edge water drive. The average percentage increase in oil cumulative volume was 0.40% in fovour of bottom water drive. Further sensitivity on cumulative oil recovered showed the increase in reservoir size with increasing aquifer volumes increases oil production exponentially in bottom water drive whereas edge water drive increased linearly. Aquifer volume, aquifer permeability showed linear relationship with bottom and edge water drive.

The interpretation of aquifer responses to pumping tests is an important tool for assessing aquifer geometry and properties, which are critical in the assessment of water resources or in environmental remediation. However, the responses of aquifers, measured by time-drawdown relationships in monitoring wells, are nonunique solutions that are affected by many factors. Jacob’s Zoo is a collection of graphical interpretations that allows students and practitioners to develop an intuitive feel for how natural hydrogeological systems work, and develop a set of skills that provide a better understanding of aquifer properties far beyond interpretation of pumping tests. Jacob’s Zoo, based on the work of Jacob (1950), fosters a deeper understanding, although few practitioners realize the full utility of the method. Jacob CE (1950) Flow of groundwater, In: Rouse H (ed) Engineering Hydraulics, Wiley, New York. P 321–386.

Streamflow hydrograph analysis has long been used for separating streamflow into baseflow and surface runoff components, providing critical information for studies in hydrology, climate and water resources. Issues with established methods include the lack of physics and arbitrary choice of separation parameters, problems in identifying snowmelt runoff, and limitations on watershed size and hydrogeological conditions. In this study, a Gravity Recovery and Climate Experiment (GRACE)-based model was developed to address these weaknesses and improve hydrograph separation. The model is physically based and requires no arbitrary choice of parameters. The new model was compared with six hydrograph separation methods provided with the U.S. Geological Survey Groundwater Toolbox. The results demonstrated improved estimates by the new model particularly in filtering out the bias of snowmelt runoff in baseflow estimate. This new model is specifically suitable for applications over large watersheds which is complementary to the traditional methods that are limited by watershed size. The output from the model also includes estimates for watershed hydraulic conductivity and drainable water storage, which are useful parameters in evaluating aquifer properties, calibrating and validating hydrological and climate models, and assessing regional water resources.

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.

Nde Division in West-Cameroon is facing with water supply although many attempts of restoring existing SCANWATER facilities by Bangangte Municipality. In order to address the issue, we assess the exploitable pumping flow rate of catchment aquifers and its hydraulic properties by using Jacob and Theis method, and define protection zones with Hoffman and Lillich method. It emerges that the hydraulic conductivity of aquifer is in the order of 10-4 m/sec, transmissivity varies from 10-4 to 10-6 m2/sec. Aquifer pumping flow rate (Q) varies between 1.5 and 10.5 m3/h. In volcanic rocks, aquifer is more productive (4.5 ≤ Q ≤ 10.5 m3/h). Transfer time of pollutants to aquifer varies from 3 to 56 days depending on rock-types and groundwater slope (0.03 - 0.13 m/m). Furthermore, 113,624 m and 1123 m are radius to be implemented for a better protection of groundwater against any form of pollutant.

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

In 2018, large parts of northern Europe were affected by an extreme drought. A better understanding of the characteristics and the large-scale atmospheric circulation driving such events is of high importance to enhance drought forecasting and mitigation. This paper examines the historical extremeness of the May–August 2018 meteorological situation and the accompanying meteorological and hydrological (streamflow and groundwater) drought. Further, it investigates the relationship between the large-scale atmospheric circulation and summer streamflow in the Nordic region. In May and July 2018, record-breaking temperatures were observed in large parts of northern Europe associated with blocking systems centred over Fennoscandia and sea surface temperature anomalies of more than 3 °C in the Baltic Sea (May, July) and the Barents Sea (July). Extreme meteorological drought, as indicated by the three-month standard precipitation index (SPI3) and precipitation-evapotranspiration index (SPEI3), was observed in May, and covered large parts of northern Europe by July. Streamflow drought in the Nordic region started to develop in June, and in July 68 % of the stations had record-low or near-record-low streamflow. Extreme streamflow conditions persisted in the southeastern part of the region throughout 2018. Many groundwater wells had record-low or near-record-low levels in July and August. However, extremeness in groundwater levels and (to a lesser degree) streamflow show a diverse spatial pattern. This points to the role of local terrestrial processes in controlling the hydrological response to meteorological conditions, including aquifer properties. Composite analysis of low summer streamflow and 500 mb geopotential height anomalies revealed a distinction between summer streamflow variability in western/northern Norway and the rest of the region. Low summer streamflow in western/northern Norway is related to high-pressure systems centred over the Norwegian Sea. In the rest of the Nordic region, low summer streamflow is associated with a high-pressure system over the North Sea and a low-pressure system over Greenland and Russia at similar latitudes, resembling the pattern of 2018. This study provides new insight into different hydro-meteorological aspects of the 2018 northern European drought, as well as identification of large-scale atmospheric circulation patterns associated with summer streamflow drought in the Nordic region.

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.

Sustainable groundwater aquifers are critical in arid and semiarid countries due to the scarcity of surface water and precipitation. Management of groundwater resources requires estimation of aquifer properties and interaction between multilayers in heterogeneous aquifers. A three-dimensional groundwater flow model was implemented to simulate a complex multilayer aquifer in Oman. Steady-state model was calibrated using groundwater level data in July 2016. Both the automated parameter calibration technique and manual trial and error method were applied for calibrating hydraulic conductivity, groundwater recharge, and anisotropy of soil layers. The optimum set of parameters of 14 observation wells was obtained from the simulation with minimum root mean square error of 0.8 m for groundwater water level. The calibrated model was validated using measured data for October 2016, and root mean square error was found to be 0.81 m for groundwater water level. Among the observation wells which were used in the above analysis, 4 of them were directed to different aquifer depths and each two observation wells were in the same location. These two sets of wells, therefore, were used for analyzing interactions among different aquifer layers. Results showed that increased pumping rates enhanced water transfer between multilayers due to increased hydraulic gradient. The effect was more dominant in layers with high vertical hydraulic conductivity. Also, the sensitivity analysis was performed and results indicated that the predicted water level was less sensitive to vertical anisotropy. The findings of this study could be useful for decision-makers for better management of groundwater resources in arid regions.

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.

Research into the unsaturated zone and groundwater recharge can greatly improve understanding of hydrological processes and assist in sustainable groundwater management. Groundwater recharge of the Ljubljana Field aquifer, a coarse-gravel porous aquifer in Slovenia, was estimated with reference to soil characteristics, outflow data from a weighing lysimeter, and water-table fluctuation. The specific yield of the upper unsaturated zone determined from soil characteristics was 0.141 for the top soil layer (0–0.35 m), between 0.042 and 0.066 for the layer below the top soil (0.35–1.3 m), and between 0.239 and 0.219 for the underlying upper coarse layer. During long dry periods, especially in combination with times of high plant-water requirements, only substantial precipitation events directly contribute to considerable groundwater recharge, as ‘substantial precipitation’ is defined as those rainfall events that fill storage and exceed retention capacity of the upper soil layer. Lysimeter measurements show that 50% of the precipitation is lost by evapotranspiration and the other 50% contributes to groundwater recharge. Most infiltrated water was stored for a short time in the unsaturated zone and did not result in a significant discharge from the lysimeter. Average specific yield, calculated using the water-table fluctuation method, was 0.144. The nature of the gravely unsaturated zone is that once the retention buffer of the soil is exceeded, the water front travels through relatively quickly, which can be seen as an advantage for recharge or a disadvantage for prevention of groundwater pollution.

An accurate prediction of groundwater level is quite essential for ecological, sustainable development and management of groundwater resources. The soft computing models like ARIMA, ANN, FL, ANFIS and GA have been reported as the promising tools in prediction of accurate groundwater level. Now a day’s, ANN is widely used by many researchers in groundwater level prediction. So, the present study was carried out to find best ANN model to predict groundwater level fluctuation at Manvi. Selection of significant input variables is the most important step in the development of ANN model. In general, all of the relevant input variables (Rainfall, ET, temperature, RH, recharge, discharge, aquifer properties, streams, infiltration, initial groundwater level and variable groundwater level in nearby wells) will be equally informative in many instances. Further some may be difficult to collect, noisy, correlated or have no significant relationship with the output variable (current groundwater level) being modelled. The statistical parameters viz., auto-correlation function (ACF), partial auto-correlation function (PACF) and cross-correlation function (CCF) were used to select the significant variables with significant lag times. MATLAB 7.14 was used for statistical analysis and interpretation. Results indicated that, rainfall, evapotranspiration and previous groundwater level showed a good correlation with current groundwater level. It was found that considerable lag time of one month in case of rainfall (R) and previous groundwater level (Wt) and four months lag time of evapotranspiration (ET). So, input with R (t-1), Wt (t-1) and ET (t-4) lags were selected for ANN modelling. Good prediction was observed by the developed model.

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...