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The Chernobyl Pilot Site (CPS) was created in 2000 in order to study radionuclide migration processes to the geosphere from radioactive material of the Red forest buried in a trench. In this article, the data collected in the CPS up to 2015 are analyzed to identify the links between hydrological conditions and release of strontium-90 ( 90 Sr) from the trench. Then, a flow-and-transport model is used for simulating distribution of 90 Sr both in the unsaturated and saturated zones downstream of the trench. The results show that the 90 Sr activity in groundwater is strongly transient in time, due to the high inter-annual variability of both the recharge rate and the groundwater level (some particularly wet winters resulted in saturation of the bottom part of the trench). In addition, the parameters that govern the sorption of 90 Sr in trench material appear to vary significantly in space (the retardation factor ranges from 10 to 50 depending on the location). This spatiotemporal variability could hide some critical processes, e.g., related to a long-term trend, and needs to be characterized through an appropriate sampling frequency., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022. Published by Elsevier Ltd.)

The growing global demand for drinking water is driving both the diversification of water supply sources and their sustainability. River bank filtration (RBF) is an excellent option since it strongly reduces the extent of treatment steps compared to direct usage of surface water. Organic micropollutants (e.g. pharmaceuticals) are widely recognized as a hazard in drinking water production from surface water. Due to their potentially high mobility, stability, bioaccumulation and persistency, these substances can pass through RBF-systems. Scientific studies on compound removal and attenuation efficiency of RBF rely on the knowledge of travel time to compare concentrations in the river to the ones in the bank filtrate since water quality in rivers can change rapidly. However, bank filtrate samples represent a mixture of water with different travel times as the flow paths vary. This has not yet been considered in studies of bank filtration removal efficiency for organic micro pollutants. Here we present a method that considers the residence-time distribution of the bank filtrate sample obtained by groundwater modelling to evaluate the removal efficiency of RBF for organic micropollutants. The method was tested in a comprehensive study with 50 samples taken over a one-year-period at a river bank filtration site in Vienna (Austria). Our findings revealed that better coverage of varying river water quality (higher sampling frequency during the period of infiltration) resulted not only in a higher number of compounds considered as removed but also significantly reduced the number of compounds considered to have formed during the RBF process. The application of the presented method indicated that RBF is very effective in removing organic micropollutants. Considering different travel times will provide better models and a better understanding of the potential of RBF for pollutant removal and thus supports its safe application as a solution to the growing demand for drinking water., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier Ltd.)

Natural Attenuation (NA) processes have been demonstrated to reduce pollutant loads at different contaminated groundwater sites world-wide and are increasingly considered in contaminated site management concepts. However, data are mainly available for steady state groundwater flow and stable redox conditions as well as pollutants listed in standard regulatory schemes. In this study, the influence of transient groundwater flow and redox conditions on NA was examined at a former gas works site near the river Rhine in Germany. The investigated 78 pollutants included 40 mono- and polyaromatic hydrocarbons (MAHs, PAHs) and 38 NSO-heterocyclic aromatic hydrocarbons (NSO-HET). In the highly polluted areas, the MAHs benzene, indene and indane, the PAHs naphthalene, acenaphthene, 1- and 2-methylnaphthalene and the NSO-HET 2-methylquinoline, carbazole, benzothiophene, dibenzofuran and benzofuran were predominant. Pollutant concentrations decreased with increasing distance from the sources of contamination. At the plume fringes, the MAHs benzene and indane, the PAH acenaphthene, the NSO-HET carbazole, 5-methylbenzothiophene, 2- and 3-methylbenzofuran and 2-methyldibenzofuran were predominant, indicating low retention and slow intrinsic biodegradation of these compounds. The influence of surface water on groundwater level, pollutant concentrations, and redox conditions in the monitoring wells was observed with a permanently installed groundwater sensor. The temporary availability of oxygen was observed at the plume fringes, resulting in aerobic and ferric iron reducing biodegradation processes. Field and laboratory data were used to set-up a groundwater flow and reactive transport model used for quantification of the field mass transfer rates. In conclusion, the study demonstrates that NA is effective under transient flow and redox conditions. A conceptual model and reactive transport simulation can facilitate the interpretation of pronounced fluctuations of pollutant concentration in monitoring wells. Based on the analysis of 78 pollutants, indane, indene and several NSO-HET like carbazole, benzothiophene and 2-methyldibenzofuran are recommended for monitoring at tar oil polluted sites, besides EPA-PAHs and BTEX., (Copyright © 2021 Elsevier B.V. All rights reserved.)

The Mar Piccolo basin is an internal sea basin located along the Ionian coast (Southern Italy), and it is surrounded primarily by fractured carbonate karstic environment. Because of the karstic features, the main continental water inflow is from groundwater discharge. The Mar Piccolo basin represents a peculiar and sensitive environment and a social emergency because of sea water and sediment pollution. This pollution appears to be caused by the overlapping effects of dangerous anthropogenic activities, including heavy industries and commercial and navy dockyards. The paper aims to define the contribution of subaerial and submarine coastal springs to the hydrological dynamic equilibrium of this internal sea basin. A general approach was defined, including a hydrogeological basin border assessment to detect inflowing springs, detailed geological and hydrogeological conceptualisation, in situ submarine and subaerial spring measurements, and flow numerical modelling. Multiple sources of data were obtained to define a relevant geodatabase, and it contained information on approximately 2000 wells, located in the study area (1600 km(2)). The conceptualisation of the hydrogeological basin, which is 978 km(2) wide, was supported by a 3D geological model that interpolated 716 stratigraphic logs. The variability in hydraulic conductivity was determined using hundreds of pumping tests. Five surveys were performed to acquire hydro-geochemical data and spring flow-yield measurements; the isotope groundwater age was assessed and used for model validation. The mean annual volume exchanged by the hydrogeological basin was assessed equal to 106.93 10(6) m(3). The numerical modelling permitted an assessment of the mean monthly yield of each spring outflow (surveyed or not), travel time, and main path flow.

Offshore freshened groundwater (OFG) represents a significant, yet underexplored, component of the global freshwater system as it is found across various continental margins. In this study, a 3-D geological and groundwater model was developed for the Canterbury Plains and Bight (New Zealand) to assess the role of present-day onshore recharge in the emplacement of OFG. Topographic and bathymetric, seismic reflection and well data have been integrated to construct an onshore-offshore geological model. The facies property distribution and associated hydrodynamic parameters were determined using stochastic modelling techniques. The geological reconstruction was imported within a variable density groundwater model. Simulations, under transient regime, were run until equilibrium conditions between the involved aquifer portion and the adjacent ocean have been reached. Our results show that the geological model accurately captures the stratigraphic and sedimentary features of the area, and that onshore recharge at present contributes to OFG emplacement up to 15 km from the coast, which is equivalent to 25% of its maximum extent. Onshore recharge during sea-level lowstands is therefore the dominant OFG emplacement mechanism in the Canterbury Bight. [ABSTRACT FROM AUTHOR]

The national-scale British Groundwater Model (BGWM) is implemented to simulate groundwater dynamics and budgets in Great Britain. Notwithstanding the challenges of integrating a very large amount of data, finding a trade-off between computational efficiency and realism, performing automatic calibration, and addressing multiple sources of structural and parameter uncertainty, a quantitative–qualitive evaluation approach showed that the BGWM provides a reasonably accurate digital representation of groundwater systems and processes at a national scale. In this work, the model was applied to understand the variability of budget components across multiple spatial and temporal scales. Comparisons showed regional differences linked to lithological and climatic factors, which in turn can be associated with more or less groundwater resilience to extreme climatic events. There is confidence that the current and future versions of the BGWM can become valuable tools for effective water resources management and adaptation strategies under future climatic and population changes. [ABSTRACT FROM AUTHOR]

This paper presents an approach to estimate the effects of a managed recharge experiment in a multilayer aquifer characterized by the presence of perched water tables in the Medina del Campo groundwater body, Douro basin, central Spain. A numerical model was developed to evaluate the effect of artificial recharge on the shallow sector of a regional‐scale aquifer and on formerly active wetlands. The model was developed in the Visual MODFLOW Pro v.2011.1 environment in order to represent and analyse the regional impact of this artificial recharge event. Results suggest that the assumption of a single perched system may prove useful in regional contexts where data is limited. From a study site perspective, managed recharge is observed to increase shallow storage along the riverbanks, which is considered valuable for environmental purposes. However, downstream wetlands are unlikely to experience a significant recovery. Furthermore, only a small percentage of artificial recharge is expected to reach the deep regional aquifer. This method can be exported to settings characterized by the presence of perched aquifers and associated groundwater dependent ecosystems. [ABSTRACT FROM AUTHOR]

Groundwater is the primary source of water supply in Ethiopia. The study area was challenged due to increasing water demand, uneven water resource distribution, and noticeable changes in groundwater levels. The study focused on the examining of existing abstraction and future water demand scenarios on groundwater balance in the Weyib watershed using the WetSpass-M and MODFLOW-2005 models. The input datasets, such as aquifer properties, observed groundwater heads, hydrogeology, groundwater recharge, the Digital Elevation Model (DEM), and hydrological data were used. Datasets were prepared to better represent subsurface hydrology and its future demand effects evaluated using calibrated steady-state numerical groundwater modeling. The WetSpass-M and MODFLOW-2005 models depicted good performances during the simulations of groundwater recharge and groundwater budget under existing abstractions and estimated demand scenarios, respectively. The mean annual groundwater recharge estimated was 177.66 mm/year. The existing groundwater abstraction was 34,686.39, estimated short-term and long-term water demand scenarios were 72,113.61 and 93,795.57 m3/day, respectively. The upstream area has the highest groundwater head and recharge, while decreasing as it approaches the Weyib watershed outlet. During the outflow groundwater budget, the groundwater abstractions increased as expenses of river leakage and head dept. bounds increased. Moreover, the increasing groundwater withdrawal would reduce groundwater heads, and the estimated future water demand scenarios would substantially impact the groundwater budget, which would also have an impact on the watershed hydrology and ecosystem. [ABSTRACT FROM AUTHOR]

Groundwater (GW) flooding mechanisms differ from river flooding, both spatially and temporally, and preventative methods against groundwater flooding must take this into account. Although groundwater flooding caused by a rise of river water seldom occurs, it can occasionally become severe and last for a long time if the river is significantly flooded. In the southwest portion of the research domain, Friedrichshafen, Germany, with a few urban communities, the level of the groundwater table was discovered to be roughly 1 m below the surface. In the study region, it is typical for the bottom level of the foundation of a single-story building to extend up to a depth of about 1.5 m. Therefore, flood mitigation methods are taken into account for the southwest portion of the study region. In this study, FEFLOW is used to explore the preventative methods for groundwater flooding caused by river water increase in urban settings, the spread of contamination, and the strategizing of effective mitigation solutions for flooding. The installation of a pumping well, drainage, and a barrier in the affected area are three different flood control strategies that are taken into consideration for the study area. Pumping well installation, reducing up to 1.5 m of hydraulic head, was found to be the most effective flood control measure locally in a small region. By contrast, removing groundwater by building drainage and barriers was shown to be ineffective for lowering the groundwater table over an extended region, and was significantly more expensive than the installation of wells. Additionally, when river flooding is taken into account, compared to the default scenario where no intake of water from the river is included along the western border of the study area, it was discovered that the spread of pollution (nitrate concentration) is significantly greater. [ABSTRACT FROM AUTHOR]

Barbados is heavily reliant on groundwater resources for its potable water supply, with over 80% of the island's water sourced from aquifers. The ability to meet demand will become even more challenging due to the continuing climate crisis. The consequences of climate change within the Caribbean region include sea level rise, as well as hydrometeorological effects such as increased rainfall intensity, and declines in average annual rainfall. Scientifically sound approaches are becoming increasingly important to understand projected changes in supply and demand while concurrently minimizing deleterious impacts on the island's aquifers. Therefore, the objective of this paper is to develop a physics-based groundwater model and surrogate models using machine learning (ML), which provide decision support to assist with groundwater resources management in Barbados. Results from the study show that a single continuum conceptualization is adequate for representing the island's hydrogeology as demonstrated by a root mean squared error and mean absolute error of 2.7 m and 2.08 m between the model and observed steady-state hydraulic head. In addition, we show that data-driven surrogates using deep neural networks, elastic networks, and generative adversarial networks are capable of approximating the physics-based model with a high degree of accuracy as shown by R-squared values of 0.96, 0.95, and 0.95, respectively. The framework and tools developed are a critical step towards a digital twin that provides stakeholders with a quantitative tool for optimal management of groundwater under a changing climate in Barbados. These outputs will provide sound evidence-based solutions to aid long-term economic and social development on the island. [ABSTRACT FROM AUTHOR]

Copyright of Hydrogeology Journal is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Hydrogeology Journal is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Groundwater modelling is a commonly used technique to determine the influence of surficial processes on subsurface aquifers. In this study, a groundwater monitoring study was conducted on an agricultural field adjacent to a large drainage canal to determine the effects of the canal's operation as it relates to soil salinity during periods around flood events. The groundwater monitoring program consisted of twenty standpipes instrumented with groundwater pressure transducers that took four daily measurements. A finite element model was generated using data collected from the 2017 flood year to determine the effect of the flood on the local groundwater regime within one area consisting of four standpipes. The analysis of the model calibration yielded good to excellent results using the Nash–Sutcliffe Model Efficiency technique, with three of the four standpipes. The salt content within the model area was primarily gypsum initially derived from the underlying till and bedrock units. Model analysis indicated that various processes might impact soil salinity, including canal seepage, evapotranspiration and excessive snowmelt/recharge. The largest flood event on record for the canal was used in the calibrated model to determine the maximum extent of influence the canal has on the adjacent lands. The maximum extent of impact was found to be 112 m in the alluvial sediments and 240 m in the surficial sand structure. [ABSTRACT FROM AUTHOR]

In the present study, we show how persistent management and collection of hydrological and geophysical data at a national scale can be combined with innovative analysis methods to generate decision support tools for groundwater and surface water managers. This is exemplified by setting up a regional scale groundwater model in an area with geophysical data of varying age, type, and quality. The structure for the regional model is derived from a newly developed resistivity clay-fraction cluster analysis. This modelling strategy can be used in combination with local detailed geological modelling thus utilizing the detailed expertise locally, while securing a cost-effective (price vs. performance) solution to the numerical simulations of the regional scale water balance. In this way we avoid unwanted boundary effects on the local model simulations due to the presence of artificial numerical boundaries located proximate to the areas of interest. In this application, it is particularly important that boundary conditions are remote, due to the presence of a dense network of buried valley structures. Simulated impacts of groundwater abstraction from two existing well-fields spread through the valley system far beyond the local focus areas of the study. [ABSTRACT FROM AUTHOR]

Highlights • Emulators allow Bayesian inference for regional-scale groundwater models. • ABC provides flexibility on model calibration using different types of observations. • The impact of a proposed CSG development on groundwater in Australia is assessed. Abstract Bayesian inference provides a mathematically elegant and robust approach to constrain numerical model predictions with system knowledge and observations. Technical challenges, such as evaluating a large number of models with long runtimes, have restricted the application of Bayesian inference to groundwater modeling. To overcome such technical challenges, we use Gaussian process emulators to replace a transient regional groundwater MODFLOW model for computing objective functions during model constraining. The regional model is designed to assess the potential impact of a proposed coal seam gas (CSG) development on groundwater levels in the Richmond River catchment, Clarence-Moreton Basin, Australia. The emulators were trained using 4000 snapshots derived from the MODFLOW model and subsequently used to replace the MODFLOW model in an Approximate Bayesian Computation (ABC) scheme. ABC was deemed the more appropriate choice as it relaxes the need to derive an explicit likelihood function that the formal Bayesian analysis requires. The study demonstrated the flexibility of the Gaussian process emulators, which can accurately reproduce the original model behavior at a fraction of the computational cost (from hours to seconds). The gain in computational efficiency using the proposed approach allows the global calibration and uncertainty algorithms to become more feasible for computationally demanding groundwater models. Based on the ABC analysis, the probability for the simulated CSG development causing a water table change of more than 0.2 m was less than 5%. In addition to a probabilistic estimate of the prediction, an added value of emulator-assisted ABC inference is providing information on the extent to which observations can constrain parameters and predictions, as well as the flexibility to include various quantitative and qualitative parameter constraining information. [ABSTRACT FROM AUTHOR]

In this study impact of climate change on groundwater recharge is investigated and the carbon emission from groundwater irrigation is assessed under projected climate change scenarios for Karnal district of Haryana state in India. HYDRUS-1D and MODFLOW models were used to simulate the climate change impacts on groundwater recharge for different projected climate change scenarios. Simulation results showed that groundwater recharge would increase marginally by 2030 over the baseline year of 2008 under the scenario based on ARIMA predictions, which considered the effect of all climate parameters. However, under the scenarios, which considered only rise in temperature, groundwater recharge would decrease by 0.07-0.22 m. Rise in temperature by 3.5°C and 4.3°C along with 9% and 16% increase in rainfall over the base year would increase the recharge by 0.09 m and 0.14 m respectively. The study also revealed that the effect of climate change on cumulative recharge would be more in sugarcane fields than in rice fields. Carbon emission of groundwater irrigation under the scenarios based on rise in temperature only would increase by a minimum of 12 kg CO2/ha in pearl millet crop by the year 2030 to a maximum of 3250 kg CO2/ha for sugarcane crop by the end of this century. Estimated total carbon emission in 2030 would be 345,857 metric tonne from groundwater irrigation in Karnal district which is 87,474 metric tonne more than the baseline emission. [ABSTRACT FROM AUTHOR]

Groundwater modelling calls for an effective and robust data integrating method to fill the gap between the model and observation data. The ensemble Kalman filter (EnKF), a real‐time data assimilation method, has been increasingly applied in multiple disciplines such as petroleum engineering and hydrogeology. In this approach, a groundwater model is updated sequentially with measured data such as hydraulic head and concentration. As an alternative to the EnKF, the ensemble smoother (ES) has been proposed for updating groundwater models using all the data together, with much less computational cost. To further improve the performance of the ES, an iterative ES has been proposed for continuously updating the model by assimilating measurements together. In this work, we compare the performance of the EnKF, the ES, and the iterative ES using a synthetic example in groundwater modelling. Hydraulic head data modelled on the basis of the reference conductivity field are used to inversely estimate conductivities at unsampled locations. Results are evaluated in terms of the characterization of conductivity and groundwater flow predictions. It is concluded that (a) the iterative ES works better than the standard ES because of its continuous updating and (b) the iterative ES could achieve results comparable with those of the EnKF, with less computational cost. These findings show that the iterative ES should be paid much more attention for data assimilation in groundwater modelling. [ABSTRACT FROM AUTHOR]

This study is the first to assess land subsidence in the Kathmandu Valley, Nepal. Land subsidence simulations were based on a fully calibrated groundwater (GW) flow model developed using a coupled surface–subsurface modelling system. Subsidence is predicted to occur as a result of deep aquifer compaction due to excessive GW abstraction. The north and north-east areas at the periphery of the GW basin are hotspots for this subsidence. The estimated subsidence is most sensitive to changes in land cover within the recharge areas. The model shows the Melamchi water supply project assists in the control of subsidence to some extent. In the absence of land subsidence measurements, this paper highlights the location and the potential levels of the subsidence hazard which will be useful for hazard prevention management. Additionally, this work provides a basis to design field investigations, monitoring networks for land subsidence and upgrading the present GW monitoring network. Although the study has presented a preliminary analysis, a more comprehensive model inclusive of clay subsidence is required to address the subsidence vulnerability of the central densely populated core of the valley, which reflects the need for a comprehensive database of the hydrogeology in the valley. [ABSTRACT FROM AUTHOR]

Copyright of Hydrogeology Journal is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In the actual evolving energy context, characterized by an increasing part of intermittent renewable sources, the development of energy storage technologies are required, such as pumped storage hydroelectricity (PSH). While new sites for conventional PSH plants are getting scarce, it is proposed to use abandoned underground mines as lower reservoirs for Underground Pumped Storage Hydroelectricity (UPSH). However, the hydrogeological consequences produced by the cyclic solicitations (continuous pumpings and injections) have been poorly investigated. Therefore, in this work, groundwater interactions with the cyclically fill and empty cavity were numerically studied considering a simplified description of a slate mine. Two pumping/injection scenarios were considered, both for a reference slate rock case and for a sensitivity analysis of variations of aquifer hydraulic conductivity value. Groundwater impacts were assessed in terms of oscillations of piezometric heads and mean drawdown around the cavity. The value of the hydraulic conductivity clearly influences the magnitude of the aquifer response. Studying interactions with the cavity highlighted that seepage into the cavity occurs over time. The volume of seeped water varies depending on the hydraulic conductivity and it could become non-negligible in the UPSH operations. These preliminary results allow finally considering first geological feasibility aspects, which could vary conversely according to the hydraulic conductivity value and to the considered groundwater impacts. [ABSTRACT FROM AUTHOR]

The sophisticated research and management problems of the Estonian water environment are considered by means of holistic modelling. The model elaborated is based on the computer code Visual MODFLOW Classic. The model encompasses the entire Estonian Artesian Basin (EAB) and the border districts of Russia and Latvia. It involves all main aquifers and aquitards on an area of 88,000 km2. The main hydrogeological and hydrological characteristics of the study area, including the time-dependent three-dimensional distribution of groundwater heads, the direction, velocity and rate of subsurface fluxes, itemised water budgets, volumes of hydrogeological units, and durations of groundwater exchange have been determined by modelling. The palaeohydrological situation during the last continental glaciation of the EAB was reconstructed and the principal problems of the sustainable management of water environment were elucidated. The model has been used to simulate the local and cumulative rates of the base flow. [ABSTRACT FROM AUTHOR]

Since last decade, the value per barrel of potable groundwater has outpaced the value of a barrel of oil in many areas of the world. Hence, proper assessment of groundwater potential and management practices are the needs of the day. Establishing relationship between remote sensing data and hydrologic phenomenon can maximize the efficiency of water resources development projects. Present study focuses on groundwater potential assessment in Salem district, Tamil Nadu to investigate groundwater resource potential. At the same, all thematic layers important from ground water occurrence and movement point of view were digitized and integrated in the GIS environment. The weights of different parameters/themes were computed using weighed index overlay analysis (WIOA), analytic hierarchy process (AHP) and fuzzy logic technique. Through this integrated GIS analysis, groundwater prospect map of the study area was prepared qualitatively. Field verification at observation wells was used to verify identified potential zones and depth of water measured at observation wells. Generated map from weighed overlay using AHP performed very well in predicting the groundwater surface and hence this methodology proves to be a promising tool for future. [ABSTRACT FROM AUTHOR]

In developing countries such as Syria, the lack of hydrological data affects groundwater resource assessment. Groundwater models provide the means to fill the gaps in the available data in order to improve the understanding of groundwater systems. The study area can be considered as the main recharge area of the eastern side of Barada and Awaj basin in the eastern part of Mt. Hermon. The withdrawal for agricultural and domestic purposes removes a considerable amount of water. The steady-state three-dimensional (3D) groundwater model (FEFLOW which is an advanced finite element groundwater flow and transport modeling tool), was used to quantify groundwater budget components by using all available data of hydrological year 2009-2010. The results obtained may be considered as an essential tool for groundwater management options in the study area. The calibrated model demonstrates a good agreement between the observed and simulated hydraulic head. The result of the sensitivity analysis shows that the model is highly sensitive to hydraulic conductivity changes and sensitive to a lesser extent to water recharge amount. Regarding the upper aquifer horizon, the water budget under steady-state condition indicates that the lateral groundwater inflow from the Jurassic aquifer into this horizon is the most important recharge component. The major discharge component from this aquifer horizon occurs at its eastern boundary toward the outside of the model domain. The model was able to produce a satisfying estimation of the preliminary water budget of the upper aquifer horizon which indicates a positive imbalance of 4.6 Mm³∙y-1. [ABSTRACT FROM AUTHOR]

This work analyses the feasibility and sustainability of closed-loop heat-exchangers, also known as Borehole Heat Exchangers (BHEs), in shallow geothermal areas. By circulating a carrier fluid in a closed-loop of pipes installed vertically in a deep well, there is no fluid exchange between the BHEs and hot thermal groundwater, but only heat transfer. The BHEs absorb heat when in contact with the warmer subsoil, and release it to buildings. It is designed that heating is provided through a free-heating system, avoiding the need to use a Ground Source Heat Pump system or other thermal energy device. An actual application of such technique in a public building located in an important thermal area in north–east Italy is analysed in terms of its thermal impact on underground and groundwater temperature. The test area is part of the so called Euganean Thermal Basin (ETB), which is the most important thermal district in northern Italy. The ETB is located in the eastern Po river plain and is one of the most important thermal and mud-therapeutic spas in the world. More than 250 hotels offer hospitality to more than 3 million tourists every year. Almost every hotel and spa owns a well to extract thermal water at a temperature in the range 60–87 °C from the fractured carbonatic bedrock found at a depth of about 50–200 m below ground level. To preserve this fundamental resource, the local legislation does not allow extracted thermal water to be used for purposes other than therapeutic ones. Several spas and thermal wells are present in the surroundings of the concerned building and it must be verified that heat extraction by the BHE-array during its operation does not hinder the temperature of thermal wells. The analysis is carried out using a finite elements analysis code (FEFlow 6.1), simulating mass and heat transfer inside porous media. Various array configurations are simulated and it is found that an array of 4 BHEs 240 m deep provide enough thermal energy to the building decreasing by less than 2 °C the temperature of the closest well's extracted water. A feasibility analysis of a more widespread District Heating scheme in the Euganean Thermal Basin area should therefore be carried out. [ABSTRACT FROM AUTHOR]

The purpose of this study was to examine the impact of tunnel constructions on the steady-state groundwater head in the archaeological deposits at the Old Wharf (Bryggen) of Bergen. Water infiltration, permeabilities, and boundary conditions were deduced from available data and supplemented by leakage measurements into the existing railway tunnel located upstream of the Bryggen area. The pore water in the deposits at Bryggen has different origins viz . precipitation; leakage from drainage systems; infiltration of seawater; infiltration via the bedrock, and based on these observations, a 2D horizontal – and a 2D vertical numerical model were constructed where the seawater was the boundary at one side of the model and the groundwater divide at the other side. Given estimates of bedrock permeability and steady state infiltration rate, it was possible to calculate groundwater heads in the sediments at Bryggen that were consistent with observations, assuming that all the water percolating into the sediments flow through fractures in the bedrock. By this extreme assumption, a maximum sensitivity of the relation between groundwater flux in the bedrock and the groundwater level in the archaeological deposits was achieved. After simulation of the natural groundwater level (i.e. without any artificial extraction of water in the catchment), the impact of the water leakage into the existing tunnels was calculated. Given the relatively rough estimates of water leakage into the existing tunnels (4 L/day/meter of tunnel), the calculated decline of the groundwater head in the archaeological deposits was less than 1% of the natural groundwater level (<1 cm). If leakage rates were increased to one and two orders of magnitude, the steady state groundwater decline would be from 5% to more than 35% of the reference groundwater level (4–15 cm). The reason for these relatively robust groundwater conditions in the sediments are caused by the boundary conditions: Without any local water extraction in the deposits, the steady-state groundwater head at Bryggen will always be higher than the seawater level. A crucial point for these results was the leakage rates into the existing tunnels. Water discharge into tunnels and other subsurface constructions is the principal risk factor in this study and should be monitored before any new tunnels are constructed. [ABSTRACT FROM AUTHOR]

Hydrological models are useful tools to analyze present and future conditions of water quantity and quality. The integrated modelling of water and nutrients needs an adequate representation of the different discharge components. In common with many lowlands, groundwater contribution to the discharge in the North German lowlands is a key factor for a reasonable representation of the water balance, especially in low flow periods. Several studies revealed that the widely used Soil and Water Assessment Tool (SWAT) model performs poorly for low flow periods. This paper deals with the extension of the groundwater module of the SWAT model to enhance low flow representation. The current two-storage concept of SWAT was further developed to a three-storage concept. This was realized due to modification of the groundwater module by splitting the active groundwater storage into a fast and a slow contributing aquifer. The results of this study show that the groundwater module with three storages leads to a good prediction of the overall discharge especially for the recession limbs and the low flow periods. The improved performance is reflected in the signature measures for the mid-segment (percent bias −2.4% vs −15.9%) and the low segment (percent bias 14.8% vs 46.8%) of the flow duration curve. The three-storage groundwater module is more process oriented than the original version due to the introduction of a fast and a slow groundwater flow component. The three-storage version includes a modular approach, because groundwater storages can be activated or deactivated independently for subbasin and hydrological response unit level. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Copyright of Hydrogeology Journal is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Uneven distribution of domestic water in space and time is a major concern in many fast growing cities due to improper planning and lack of scientific approach. This problem is much severe where the maximum domestic water requirements are met from the groundwater resources. Optimising a single groundwater pumping scheme may be an easy task using simple linear programming technique but, if the number of pumping schemes and constraints are more, solutions for identifying such groundwater schemes are more difficult and laborious using conventional methods as the constraints varies in space and time. In this paper, a new technique was developed to identify new groundwater pumping schemes to meet the present and future domestic water requirements in space and time by integrating spatial optimisation technique with the groundwater model. The approach considers the possible optimum rate of groundwater pumping, minimising the cost of water supply scheme and having minimum impact on the downstream side groundwater table using high resolution satellite data (IKONOS), Geographical Information System (GIS) tools and optimisation techniques. Dehradun, which is one of the fast growing cities in India, was considered as a study area to demonstrate the proposed new technique. Domestic water demand for next two decades (up to 2,031) was forecasted and compared with the existing supplies. Nearly 48 additional groundwater pumping schemes were identified to cater the present and future demands. Its impact on the groundwater table was also studied using groundwater modelling technique. [ABSTRACT FROM AUTHOR]

Groundwater fluxes in tidal marshes largely control key ecosystem functions and services, such as vegetation growth, soil carbon sequestration, and nutrient cycling. In tidal marshes restored on formerly embanked agricultural land, groundwater fluxes are often limited as compared to nearby natural marshes, as a result of historical agricultural soil compaction. To improve the functioning of restored tidal marshes, knowledge is needed on how much certain design options can optimize soil-groundwater interactions in future restoration projects. Based on measured data on soil properties and tidally induced groundwater dynamics, we calibrated and evaluated a 2D vertical model of a creek-marsh cross-section, accounting for both saturated and unsaturated groundwater flow and solute transport in a variably saturated groundwater flow model. We found that model simulations of common restoration practices such as soil amendments (increasing the depth of porous soil on top of the compact layer) and creek excavation (increasing the creek density) increase the soil aeration depth and time, the drainage depth and the solute flux, and decrease the residence time of solutes in the porewater. Our simulations indicate that increasing the depth to the compact layer from 20 cm to 40 cm, or increasing the creek density from 1 creek to 2 creeks along a 50 m marsh transect (while maintaining the total creek cross-sectional area), in both cases more than doubles the volume of water processed by the marsh soil. We discuss that this may stimulate nutrient cycling. As such, our study demonstrates that groundwater modelling can support the design of marsh restoration measures aiming to optimize groundwater fluxes and related ecosystem services. [Display omitted] • Historical soil compaction limits groundwater flow in restored tidal marshes • Seepage volumes were found to be 6 times less in restored marsh with compact subsoil • Creek excavation and soil amendments increase soil – groundwater interactions • Groundwater modelling is a useful tool to optimize tidal marsh restoration design [ABSTRACT FROM AUTHOR]

Water flow and water storage in hill slopes have a strong interest in the hydrological scientific community. The use of the gravimetrical signal of superconducting gravimeters can help to understand water flow in such areas. At the Geo-dynamic Observatory Moxa of the Friedrich Schiller University Jena (Germany), the relation between hill slope hydrological processes and gravity residuals are investigated. For this purpose a linear reservoir model was developed to quantify canopy storage and storage changes in the unsaturated zone. A groundwater flow model (MODFLOW) was developed to quantify flow in fractured shales. Cross correlation showed significant gravimetrical response on heavy precipitation events after a dry period. The groundwater model simulated the expected flow patterns reasonably well. [ABSTRACT FROM AUTHOR]

DIVAST is a two-dimensional hydrodynamic and water quality numerical model developed for estuarine and coastal modelling. The original model enables the simulation of problems such as pollution and flooding in surface waters. In this paper the existing model is extended to allow the modelling of 2-D groundwater as well as surface water in the same model, using an integrated approach rather than two disparate models. The changes to the original model are summarised and the method of implementation is outlined. The new extended model (DIVAST-SG) is then tested against an analytical solution to verify that the model solves the equations correctly. The model is shown to predict the analytical solution for two different scenarios to within approximately 1 % of the height of flood wave. [ABSTRACT FROM AUTHOR]

Abstract: When running a groundwater flow model, a recurrent and seemingly subsidiary question arises at the starting step of computations: what value of acceleration parameter do we need to optimize the numerical solver? A method is proposed to provide a practical estimate of the optimal acceleration parameter via a geostatistical analysis of the spatial variability of the logarithm of the transmissivity field Y. The background of the approach is illustrated on the successive over-relaxation method (SOR) used, either as a stand-alone solver, or as a symmetric preconditioner (SSOR) to the gradient conjugate method, or as a smoother in multigrid methods. It shows that this optimum acceleration factor is a function of the standard deviation and the correlation length of Y. This provides an easy-to-use heuristic procedure to estimate the acceleration factors, which could even be incorporated in the software package. A case study illustrates the steps needed to perform this estimation. [Copyright &y& Elsevier]

Summary: About three – quarters of all water used in the south-western Australia is from groundwater. A decline in rainfall since about 1975 and increased abstraction has resulted in some groundwater levels declining and groundwater dependent ecosystems decreasing in health and extent. Levels are rising under some areas used for dryland (rainfed) agriculture because crops and pastures are shallow rooted. Almost all global climate models (GCMs) project a drier and hotter climate for the region by 2030. In this project, five climate scenarios were applied to groundwater models to estimate groundwater levels in the region in 2030. The climate scenarios were (i) a continuation of the historical climate of 1975–2007; (ii) a continuation of the more recent climate of 1997–2007 until 2030; and (iii–v) three climate scenarios derived by applying the GCM projected climate under three global warming scenarios of 0.7, 1.0 and 1.3°C by 2030. A sixth scenario considered increasing abstraction levels to maximum allowed levels under a median future climate (1.0°C warming). Groundwater levels were found to be much less affected than surface water resources by a future drier climate as well as for a continuation of the climate experienced since 1975. For a fixed rainfall, recharge was highest where soils were sandy, there was little or no perennial vegetation and the watertable was neither very shallow nor very deep. A feature of the project area is that about half has a watertable within 10m of the soil surface, and about a quarter within 3m. Levels were not as affected by a decline in rainfall when reduced groundwater drainage and evapotranspiration losses offset the reduced rainfall amounts. However once a threshold groundwater level is exceeded, the rainfall fails to refill the available seasonal storage and groundwater levels decline. Projected watertables declined in all areas under a drier climate where perennial vegetation was present and able to intercept recharge or use groundwater directly. In areas under dryland agriculture, projected groundwater levels continue to rise even under a drier future climate. The climate change effects on confined groundwater systems are expected to be modest. This is due to the longer times required for the changed recharge and water level conditions in the overlying aquifers to propagate to the confined aquifers. All water balance components are projected to be impacted by climate change to a greater or lesser extent. This has consequences for the amount of extractable water from both the unconfined and confined aquifers, changes the risk of sea-water intrusion, and has implications for the groundwater dependent ecosystems. [Copyright &y& Elsevier]

Copyright of Hydrogeology Journal is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Modelling groundwater and surface water is important for integrated water resources management, especially when interaction between the river and the aquifer is high. A transient groundwater and surface water flow model was built for Ruataniwha basin, New Zealand. The model covers a long-time period; starting in 1990, when water resources development in the area started, to present date. For a better resolution, the simulation period was divided into 59 stress periods, and each stress period was divided to 10 time steps. The model uses data obtained from surface water, and groundwater collected over the last 20 years. Rivers and streams were divided into 28 segments and flow and streambed data at the beginning and end of each segment was used. Parameter estimation and optimisation 'PEST' was used for automatic calibration of hydraulic conductivity, groundwater recharge and storativity; whereas riverbed conductance was manually calibrated. Model results show that the rivers gain from the aquifer considerably more than the river losses. The cumulative groundwater abstraction over the last 20 years is approximately 210 million m. This amount is very low compared to other water budget components; however, the effect of groundwater abstraction on storage is significant. Based on the results of this study, it was found that the loss of storage over the last 20 years is more than 66 million m. Results also reveal that the effect of groundwater abstraction on rivers and springs flow is significant. The rivers gain from the groundwater system, and the springs flow have been decreasing. [ABSTRACT FROM AUTHOR]

Copyright of Atmosphere -- Ocean (Taylor & Francis Ltd) is the property of Taylor & Francis Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Despite the Sahelian drought of the 1970s–1990s, the unconfined aquifer in southwest Niger exhibits a multidecadal increase in groundwater reserves. Recent changes in land surface conditions have enhanced runoff and thus indirect groundwater recharge below endorheic ponds. This paper presents a model-based investigation of surface runoff and groundwater recharge at mesoscale (∼5000 km2). A new lumped-conceptual runoff model applicable to the large number of ungauged endorheic catchments is specially developed, derived from an existing fine-scale, physically-based hydrologic model. Runoff simulated for sites identified as groundwater recharge sources are used to derive recharge forcing for a Modflow-based model of the aquifer. The rising water table trend and its spatial distribution over the period 1992–2003 are generally well simulated, albeit smoothed year-to-year dynamics. Comparison with alternative methods of recharge estimation suggests, however, that there may presently exist more recharging sites and/or contributing surfaces than those considered so far. Citation Massuel, S., Cappelaere, B., Favreau, G., Leduc, C., Lebel, T. & Vischel, T. (2011) Integrated surface water–groundwater modelling in the context of increasing water reserves of a regional Sahelian aquifer. Hydrol. Sci. J. 56(7), 1242–1264. [ABSTRACT FROM AUTHOR]

This article presents an assessment of the groundwater resources in the Geba basin, Ethiopia. Hydrogeological characteristics are derived from a combination of GIS and field survey data. MODFLOW groundwater model in a PMWIN environment is used to simulate the movement and distribution of groundwater in the basin. Despite the limited data available, by simplifying the model as a single layered semi-confined groundwater system and by optimising the transmissivity of the different lithological units, a realistic description of the groundwater flow is obtained. It is concluded that 30,000 m/day of groundwater can be abstracted from the Geba basin for irrigation in a sustainable way, in locations characterised by shallow groundwater in combination with aquitard-type lithological units. [ABSTRACT FROM AUTHOR]