Journal articles: 'Coastal aquifers'

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SINGH, Somvir, Param K. GAUTAM, Prashant KUMAR, Arkoprovo BISWAS, and Tandrila SARKAR. "Delineating the characteristics of saline water intrusion in the coastal aquifers of Tamil Nadu, India by analysing the Dar-Zarrouk parameters." Contributions to Geophysics and Geodesy 51, no. 2 (June 29, 2021): 141–63. http://dx.doi.org/10.31577/congeo.2021.51.2.3.

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Tuticorin, located in the southeastern part of Tamil Nadu, is a coastal aquifer on which Vertical Electrical Sounding (VES) was conducted, thereby analysing the interpreted subsurface resistivity layer parameters covering around 112 km2 area of the study region. VES is an essential tool for investigating hard rock terrains of coastal aquifers and perceive an idea about the groundwater quality. In this study, Dar-Zarrouk (D-Z) parameters like longitudinal conductance (Sc), transverse resistance (Tr) and anisotropy (λ) are analysed as these are well-established parameters in delineating the occurrence and distribution of both fresh and saline water aquifers. These parameters are also very persuasive in investigating complex subsurface parameters (resistivity and conductivity) within saline water intruded coastal region environment. After conducting a thorough survey, the resistivity results reflect that the sediments are enriched with saltwater, clay with moderate freshwater and freshwater-bearing formations. The analysis shows that the D-Z parameters offer a helpful and assured answer in demarcating the saline, moderate fresh, and freshwater aquifers. Therefore, the behaviour and patterns of the D-Z parameters in space established the existence of saline water and freshwater aquifer structures in the coastal aquifers over a vast area.

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Mazi, K., A. D. Koussis, and G. Destouni. "Intensively exploited Mediterranean aquifers: resilience to seawater intrusion and proximity to critical thresholds." Hydrology and Earth System Sciences 18, no. 5 (May 8, 2014): 1663–77. http://dx.doi.org/10.5194/hess-18-1663-2014.

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Abstract. We investigate seawater intrusion in three prominent Mediterranean aquifers that are subject to intensive exploitation and modified hydrologic regimes by human activities: the Nile Delta, Israel Coastal and Cyprus Akrotiri aquifers. Using a generalized analytical sharp interface model, we review the salinization history and current status of these aquifers, and quantify their resilience/vulnerability to current and future seawater intrusion forcings. We identify two different critical limits of seawater intrusion under groundwater exploitation and/or climatic stress: a limit of well intrusion, at which intruded seawater reaches key locations of groundwater pumping, and a tipping point of complete seawater intrusion up to the prevailing groundwater divide of a coastal aquifer. Either limit can be reached, and ultimately crossed, under intensive aquifer exploitation and/or climate-driven change. We show that seawater intrusion vulnerability for different aquifer cases can be directly compared in terms of normalized intrusion performance curves. The site-specific assessments show that (a) the intruding seawater currently seriously threatens the Nile Delta aquifer, (b) in the Israel Coastal aquifer the sharp interface toe approaches the well location and (c) the Cyprus Akrotiri aquifer is currently somewhat less threatened by increased seawater intrusion.

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Mazi, K., A. D. Koussis, and G. Destouni. "Intensively exploited Mediterranean aquifers: resilience and proximity to critical points of seawater intrusion." Hydrology and Earth System Sciences Discussions 10, no. 11 (November 14, 2013): 13817–54. http://dx.doi.org/10.5194/hessd-10-13817-2013.

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Abstract. We investigate here seawater intrusion in three prominent Mediterranean aquifers that are subject to intensive exploitation and modified hydrologic regimes by human activities: the Nile Delta Aquifer, the Israel Coastal Aquifer and the Cyprus Akrotiri Aquifer. Using a generalized analytical sharp-interface model, we review the salinization history and current status of these aquifers, and quantify their resilience/vulnerability to current and future sea intrusion forcings. We identify two different critical limits of sea intrusion under groundwater exploitation and/or climatic stress: a limit of well intrusion, at which intruded seawater reaches key locations of groundwater pumping, and a tipping point of complete sea intrusion upto the prevailing groundwater divide of a coastal aquifer. Either limit can be reached, and ultimately crossed, under intensive aquifer exploitation and/or climate-driven change. We show that sea intrusion vulnerability for different aquifer cases can be directly compared in terms of normalized intrusion performance curves. The site-specific assessments show that the advance of seawater currently seriously threatens the Nile Delta Aquifer and the Israel Coastal Aquifer. The Cyprus Akrotiri Aquifer is currently somewhat less threatened by increased seawater intrusion.

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Gómez-Cruz, Alicia, Helga Madrigal-Solís, Christian Núñez-Solís, Hazel Calderón-Sánchez, and Pablo Jiménez-Gavilán. "Hydrogeological vulnerability in Jacó coastal aquifers, Central Pacific, Costa Rica." Revista Geográfica de América Central 2, no. 63 (June 14, 2019): 165–87. http://dx.doi.org/10.15359/rgac.63-2.6.

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In the last two decades, the Central Pacific of Costa Rica experienced a strong growth in urban and tourism development. If not regulated, this development can result in a pressure to groundwater resources and, therefore, a threat in terms of quality and quantity. In this study, a hydrogeological vulnerability map of Jacó aquifers was performed, by the GOD method. Geological profiles were elaborated, and field verification was performed. It is confirmed that, in the study area, two aquifers are found: a) a detritic, porous, unconfined coastal aquifer, settled in the Jacó alluvial plain and, b) an aquifer in the basaltic fractured rocks of the Nicoya Complex, unconfined in the mountainous zone and underlying the detritic formation in the central area, where the groundwater is integrated to that of the detrital aquifer. The zone of the alluvial aquifer resulted in a medium vulnerability index, whereas the mountainous areas in a low vulnerability. Management recommendations were proposed.

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Halder, Subrata, Lingaraj Dhal, and Madan K. Jha. "Investigating Groundwater Condition and Seawater Intrusion Status in Coastal Aquifer Systems of Eastern India." Water 13, no. 14 (July 16, 2021): 1952. http://dx.doi.org/10.3390/w13141952.

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Providing sustainable water supply for domestic needs and irrigated agriculture is one of the most significant challenges for the current century. This challenge is more daunting in coastal regions. Groundwater plays a pivotal role in addressing this challenge and hence, it is under growing stress in several parts of the world. To address this challenge, a proper understanding of groundwater characteristics in an area is essential. In this study, spatio-temporal analyses of pre-monsoon and post-monsoon groundwater levels of two coastal aquifer systems (upper leaky confined and underlying confined) were carried out in Purba Medinipur District, West Bengal, India. Trend analysis of seasonal groundwater levels of the two aquifers systems was also performed using Mann-Kendall test, Linear Regression test, and Innovative Trend test. Finally, the status of seawater intrusion in the two aquifers was evaluated using available groundwater-quality data of Chloride (Cl−) and Total Dissolved Solids (TDS). Considerable spatial and temporal variability was found in the seasonal groundwater levels of the two aquifers. Further, decreasing trends were spotted in the pre-monsoon and post-monsoon groundwater-level time series of the leaky confined and confined aquifers, except pre-monsoon groundwater levels in Contai-I and Deshpran blocks, and the post-monsoon groundwater level in Ramnagar-I block for the leaky confined aquifer. The leaky confined aquifer in Contai-I, Contai-III, and Deshpran blocks and the confined aquifer in Nandigram-I and Nandigram-II blocks are vulnerable to seawater intrusion. There is an urgent need for the real-time monitoring of groundwater levels and groundwater quality in both the aquifer systems, which can ensure efficient management of coastal groundwater reserves.

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Hermides, Demetrios, Dimitrios Zaxariadis, and George Stamatis. "Hydrochemical characteristics of the Oropos coastal aquifers, Attica, Greece." Bulletin of the Geological Society of Greece 56, no. 1 (March 8, 2020): 39. http://dx.doi.org/10.12681/bgsg.20939.

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This article deals with the hydrochemistry of coastal aquifers of the Oropos plain, Attica, Greece. It is the first study which presents hydrochemical data of the Oropos plain groundwater. Groundwater samples from 34 wells were collected and analyzed for major and heavy metal constituents. Groundwater was differentiated between the Pleistocene confined aquifer and the group of the Holocene, the Miocene and the Mesozoic aquifers based on the electrical conductivity (EC) values and the chlorides content. Groundwater in the Pleistocene sediments presented EC values ranging between 766 and 971μS/cm and chlorides between 95-163mg/l. The group of the rest aquifers presented EC values up to 3770 μS/cm and chlorides up to 993mg/l. The Pleistocene aquifer seems to be protected from seawater intrusion, although, it is located adjacent to the shoreline. In addition, most of the heavy metal concentration exceeded the EU limits. Cd, Fe, Pb, Ni have been determined at 82, 2500, 817, 217 μg/lit respectively. Groundwater was, also, categorized into 2 main water types that of Ca-Mg-HCO3 type indicating recharge of fresh water and that of Ca-Mg-Cl type indicating reverse cation exchange of old Na-Cl waters.

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Zuurbier, Koen Gerardus, and Pieter Jan Stuyfzand. "Consequences and mitigation of saltwater intrusion induced by short-circuiting during aquifer storage and recovery in a coastal subsurface." Hydrology and Earth System Sciences 21, no. 2 (February 27, 2017): 1173–88. http://dx.doi.org/10.5194/hess-21-1173-2017.

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Abstract. Coastal aquifers and the deeper subsurface are increasingly exploited. The accompanying perforation of the subsurface for those purposes has increased the risk of short-circuiting of originally separated aquifers. This study shows how this short-circuiting negatively impacts the freshwater recovery efficiency (RE) during aquifer storage and recovery (ASR) in coastal aquifers. ASR was applied in a shallow saltwater aquifer overlying a deeper, confined saltwater aquifer, which was targeted for seasonal aquifer thermal energy storage (ATES). Although both aquifers were considered properly separated (i.e., a continuous clay layer prevented rapid groundwater flow between both aquifers), intrusion of deeper saltwater into the shallower aquifer quickly terminated the freshwater recovery. The presumable pathway was a nearby ATES borehole. This finding was supported by field measurements, hydrochemical analyses, and variable-density solute transport modeling (SEAWAT version 4; Langevin et al., 2007). The potentially rapid short-circuiting during storage and recovery can reduce the RE of ASR to null. When limited mixing with ambient groundwater is allowed, a linear RE decrease by short-circuiting with increasing distance from the ASR well within the radius of the injected ASR bubble was observed. Interception of deep short-circuiting water can mitigate the observed RE decrease, although complete compensation of the RE decrease will generally be unattainable. Brackish water upconing from the underlying aquitard towards the shallow recovery wells of the ASR system with multiple partially penetrating wells (MPPW-ASR) was observed. This leakage may lead to a lower recovery efficiency than based on current ASR performance estimations.

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Harley, B. M., M. Gamache, K. K. Masterson, and R. H. Fitzgerald. "Twenty five years of operational experience using GW modeling to evaluate sustainable use of coastal aquifers for major water supplies." Water Practice and Technology 10, no. 3 (September 1, 2015): 465–73. http://dx.doi.org/10.2166/wpt.2015.053.

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The sustainable development and management of groundwater resources in coastal aquifers is complex and, historically, challenging to accomplish. Groundwater models play an essential role in addressing these complexities and providing the basis for planning future sustainable development. For more than 25 years, the authors have applied three-dimensional groundwater models to manage large scale coastal aquifers. The paper will present case studies demonstrating the application of groundwater models to evaluate conditions in complex coastal environments and to develop sustainable groundwater management strategies. These studies include Long Island, a sole source aquifer system in New York serving nearly 3 million people; aquifers in Southern California where injection barriers are used to prevent saltwater intrusion; and Savannah, Georgia in the southeastern US, where concentrated groundwater pumping has contributed to saltwater intrusion at a nearby resort island, and planning is underway to ensure a sustainable groundwater supply to both local industries and municipalities.

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Etsias, Georgios, Gerard A. Hamill, Christopher Thomson, Samuel Kennerley, Jesús F. Águila, Eric M. Benner, Mark C. McDonnell, Ashraf A. Ahmed, and Raymond Flynn. "Laboratory and Numerical Study of Saltwater Upconing in Fractured Coastal Aquifers." Water 13, no. 23 (November 24, 2021): 3331. http://dx.doi.org/10.3390/w13233331.

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This study investigated the saltwater upconing mechanism in fractured coastal aquifers. Head-induced saline intrusion was initiated into three narrow sandbox aquifers containing individual horizontal discontinuities placed on different positions. Subsequently, using a peristaltic pump, freshwater was abstracted from the aquifers’ center, triggering saltwater upconing. Progressively larger pumping rates were applied until critical conditions, resulting in the wells’ salinization, were achieved. Advanced image analysis algorithms were utilized to recreate the saltwater concentration fields and quantify the extent of the saline wedges with a high accuracy. A numerical model was successfully employed to simulate the laboratory results and conduct a comprehensive sensitivity analysis, further expanding the findings of this investigation. The impact of the fractures’ length, permeability and position on the upconing mechanism was identified. It was established that the presence of high permeability discontinuities significantly affected aquifer hydrodynamics. The conclusions of this study could constitute a contribution towards the successful management of real-world fractured coastal aquifers.

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Eissa, Mustafa A. "Application of Multi-Isotopes and Geochemical Modeling for Delineating Recharge and Salinization Sources in Dahab Basin Aquifers (South Sinai, Egypt)." Hydrology 5, no. 3 (August 4, 2018): 41. http://dx.doi.org/10.3390/hydrology5030041.

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The Dahab watershed comprises three aquifers; the alluvial Quaternary, the Early Cambrian sandstone, and the fractured Pre-Cambrian basement aquifers. The Dahab watershed is located in the southeastern part of the arid Sinai Peninsula, where low precipitation and groundwater over-exploitation deteriorate the groundwater quality in the alluvial coastal plain aquifer located downstream. Multi-isotopes including δ18O and δ2H, 87Sr/86Sr, δ81Br and δ11B coupled with groundwater geochemistry were utilized to assess the recharge source(s), water-rock interaction, and seawater mixing to aid sustainable groundwater management strategies. Br and Cl concentrations, used to measure groundwater salinity, were low in the upstream groundwater, while higher concentrations were observed in the deep drilled wells located downstream, in the main well field. The δ18O and δ2H isotopes were depleted in the upstream aquifers, but enriched in the shallow coastal aquifer, indicating slight evaporation and seawater intrusion. Higher mean values of 87Sr/86Sr and δ81Br were observed in the fresh groundwater from high in the watershed (87Sr/86Sr = 0.707716 and δ81Br = +2.05‰), while lower mean values were observed in the saline groundwater located downstream in the main well field (87Sr/86Sr = 0.706631 and δ81Br = +0.11‰). The cumulative mass balance mixing curves and the geochemical NETPATH model confirm the change of groundwater quality from the upper to lower watershed caused by the leaching and evaporation processes, as well as mixing with seawater. The corrected 14C age dating and stable isotopes show that the Quaternary and Pre-Cambrian basement aquifers contain modern groundwater, while the Early Cambrian aquifer holds paleo-groundwater, which has received considerable recharge from recent precipitation. The mixing ratiosin the Quaternary coastal aquifer range between 5% and 13% seawater to 95% and 87% fresh groundwater, respectively. These results indicate that future groundwater withdrawal must be well managed in order to limit further salinization. Groundwater withdrawal from the Quaternary coastal aquifer must be below the natural average recharge in order to be sustainable.

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Otto, C. "Dual Pump Recovery (DPR) System to Extract Freshwater in Coastal Aquifers." Journal of Agricultural and Marine Sciences [JAMS] 7, no. 2 (June 1, 2002): 73. http://dx.doi.org/10.24200/jams.vol7iss2pp73-74.

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The paper describes the hydraulic theory of recovering a dense plume using a newly devised dual pump recover system (DPR) and its feasibility to half the remediation time of a contaminated unconfined aquifer in a coastal urban environment. Although the DPR system was successfully applied to clean up the polluted aquifer, the hydraulic principles and techniques are also applicable to extract fresh groundwater from coastal aquifers without the risk of saltwater incursion.

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Caballero, Y., and B. Ladouche. "Impact of climate change on groundwater in a confined Mediterranean aquifer." Hydrology and Earth System Sciences Discussions 12, no. 10 (October 2, 2015): 10109–56. http://dx.doi.org/10.5194/hessd-12-10109-2015.

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Abstract. This paper presents an inverse modeling method based on wavelet analysis, devoted to assessment of the impacts of climate change on the groundwater resources of a confined coastal multi-layer aquifer, located in the south of France (Pyrénées-Orientales). The hydraulic behavior of the aquifer is described based on the results of a model calibrated to simulate the groundwater dynamics observed on two representative piezometers. The relative contributions of the climate and pumping forcings to the piezometric variations are quantified. The results illustrate in quantitative terms the dominant influence of pumping on the temporal variations of the hydraulic head of the aquifer. Based on this specific behavior simulation, we show the moderate vulnerability of such confined aquifers to climate change. Some insights regarding pumping strategies for confined coastal aquifers that could contribute towards preserving their good status in future are also provided.

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Lu, Chunhui, Adrian D. Werner, and Craig T. Simmons. "Threats to coastal aquifers." Nature Climate Change 3, no. 7 (June 25, 2013): 605. http://dx.doi.org/10.1038/nclimate1901.

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Lee, Woo-Dong, Young-Jae Yoo, Yeon-Myeong Jeong, and Dong-Soo Hur. "Experimental and Numerical Analysis on Hydraulic Characteristics of Coastal Aquifers with Seawall." Water 11, no. 11 (November 8, 2019): 2343. http://dx.doi.org/10.3390/w11112343.

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In this study, hydraulic model experiments were conducted to measure the saltwater–freshwater equilibrium interface in a coastal aquifer with underground obstructions such as an impermeable seawall. To analyse the hydraulic characteristics inside the coastal aquifer, numerical analysis was conducted using a non-hydrostatic Navier-Stokes solver based on the Porous Body Model (PBM), which can directly analyse groundwater flow. A unique saltwater–freshwater equilibrium interface that does not appear in typical coastal aquifer analyses was observed in a sandy tank experiment. In the experiment, the rise of the groundwater level behind the seawall increased the pressure gradient and groundwater flow rate, causing the saltwater–freshwater interface to move towards the sea and a freshwater region to form on the seabed in front of the seawall. The numerical analysis enabled close examination of the groundwater level distribution, groundwater flow, seawater–freshwater interface, and pore water pressure characteristics of the coastal aquifer with underground obstructions. The sandy tank experiment also provided an understanding of the hydraulic characteristics of groundwater in the coastal aquifer with a seawall, which previously could not be accurately analysed. The experimental and analytical results demonstrated that the rise of groundwater level due to underground obstructions in the coastal aquifer increased the pressure gradient and groundwater flow rate and slowed seawater intrusion. This principle can be employed to sufficiently reduce seawater intrusion of coastal aquifers.

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Shalev, Eyal. "Seawater Intrusion into Coastal Aquifers." Water 13, no. 19 (October 1, 2021): 2719. http://dx.doi.org/10.3390/w13192719.

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This editorial presents a representative collection of 11 papers presented in the Special Issue on Seawater Intrusion into coastal aquifers. Coastal aquifers are one of the most important water resources in the world. In addition, the natural discharge of freshwater to the sea as submarine groundwater discharge (SGD) has an important role in the ecology of marine environments. The dynamics of seawater and freshwater within coastal aquifers are highly sensitive to disturbances, and their inappropriate management may lead to the deterioration of water quality. In many coastal aquifers, seawater intrusion has become the major constraint imposed on groundwater utilization. Groundwater exploitation and climate variations create dynamic conditions, which can significantly increase seawater intrusion into aquifers and may result in the salinization of wells.

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Stoffner, Fabian, and Mustapha Mimouni. "Application of Sentinel 2 Satellite Imagery for Sustainable Groundwater Management in Agricultural Areas—Chtouka Aquifer, Morocco." Quaternary 4, no. 4 (October 31, 2021): 35. http://dx.doi.org/10.3390/quat4040035.

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In semi-arid regions that are characterized by large agricultural activities, a high volume of water is needed to cover the water requirements for agricultural production. Due to low precipitation and the associated limited availability of surface water, aquifers often represent the main source of irrigation water in these regions. Especially in coastal aquifers, high groundwater abstraction rates may change the flow dynamics of the aquifer and may lead to saltwater intrusion. In this study, within the framework of German–Moroccan international cooperation, the agricultural areas for the summer period 2019 of the Chtouka coastal aquifer in southern Morocco are classified using optical and multi-spectral Sentinel 2 data. Based on the developed land use maps, the groundwater abstraction for irrigation is then quantified by referring to local farmers’ irrigation practices. Following this approach, the total amount of groundwater abstraction is estimated at 157 million m3 for the summer period 2019 in the Chtouka aquifer.

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Voudouris, Konstantinos S. "Status and codification of karst aquifer systems in Greece." Bulletin of the Geological Society of Greece 57, no. 1 (June 7, 2021): 23. http://dx.doi.org/10.12681/bgsg.25471.

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Karst groundwater is an important natural resource for the water supply. The karst aquifer systems of Greece are developed within carbonate sedimentary (limestone, dolomite) and metamorphic rocks (marbles) and contribute significantly to water supply for domestic and irrigation use. They are discharged through springs: submarine, coastal brackish and inland freshwater springs. This review presents the general characteristics of karst aquifers focusing on hydraulic properties. Evaluation of the results shows that the hydraulic parameters of the karstic aquifer systems range within a large scale of values depending on karstification, tectonics and stratigraphy. High values of transmissivity and specific capacity are recorded in the upper stratigraphically levels of the karstic aquifer systems. In addition, a total of 229 different karst systems were classified according to five criteria: 1) Lithology, 2) Position, 3) Quality status, 4) Exploitation and quantitative status and 5) Discharge of springs. The majority (80%) of karst systems is developed in sedimentary rocks (limestones) and is of good water quality and quantitative status. Poor water quality status is recorded in coastal karst aquifers (mainly on islands) due to seawater intrusion phenomena. Finally, this work summarizes the characteristics of the karst aquifers in Greece in order to ensure the sustainable management of groundwater resources.

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El Moukhayar, R., M. Bahir, N. Youbi, N. Chkir, H. Chamchati, and P. Caréra. "Using geochemical investigations for determining the interaction between groundwater and saline water in arid areas: case of the Wadi Ouazzi basin (Morocco)." Proceedings of the International Association of Hydrological Sciences 366 (April 10, 2015): 162–63. http://dx.doi.org/10.5194/piahs-366-162-2015.

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Abstract. The characteristics of the Essaouira basin water resources are a semi-arid climate, which is severely impacted by the climate (quantity and quality). Considering the importance of the Essaouira aquifer in the groundwater supply of the region, a study was conducted in order to understand groundwater evolution in this aquifer. The Essaouira aquifer is a coastal aquifer located on the Atlantic coastline of southern Morocco, corresponding to a sedimentary basin with an area of nearly 200 km2. The control of the fluid exchange and the influence of mixing zones between the groundwater and saline water was investigated by sampling from 20 wells, drillings and sources belonging to the Plio-Quaternary and Turonian aquifers. It is hypothesized that groundwater major ions chemistry can be employed to determine the interaction between the groundwater and saline water (coastal aquifers). Groundwater samples examined for electric conductivity and temperature showed that waters belonging to the Plio-Quaternary and Turonian aquifers present very variable electric conductivities, from 900 μs/cm to 3880 μs/cm. Despite this variability, they are from the same family and are characterized by sodium-chloride facies. However, a good correlation exists between the electrical conductivity and chloride and sodium contents. The lower electrical conductivities are situated in the North quarter immediately to the south of the Wadi Ouazzi.

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Dibaj, Mahdieh, Akbar A. Javadi, Mohammad Akrami, Kai-Yuan Ke, Raziyeh Farmani, Yih-Chi Tan, and Albert S. Chen. "Modelling seawater intrusion in the Pingtung coastal aquifer in Taiwan, under the influence of sea-level rise and changing abstraction regime." Hydrogeology Journal 28, no. 6 (May 23, 2020): 2085–103. http://dx.doi.org/10.1007/s10040-020-02172-4.

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Abstract A three-dimensional variable-density finite element model was developed to study the combined effects of overabstraction and seawater intrusion in the Pingtung Plain coastal aquifer system in Taiwan. The model was generated in different layers to represent the three aquifers and two aquitards. Twenty-five multilayer pumping wells were assigned to abstract the groundwater, in addition to 95 observation wells to monitor the groundwater level. The analysis was carried out for a period of 8 years (2008–2015 inclusive). Hydraulic head, soil permeability, and precipitation were assigned as input data together with the pumping records in different layers of the aquifer. The developed numerical model was calibrated against the observed head archives and the calibrated model was used to predict the inland encroachment of seawater in different layers of the aquifer. The effects of pumping rate, sea-level rise, and relocation of wells on seawater intrusion were examined. The results show that all layers of the aquifer system are affected by seawater intrusion; however, the lengths of inland encroachment in the top and bottom aquifers are greater compared with the middle layer. This is the first large-scale finite-element model of the Pingtung Plain, which can be used by decision-makers for sustainable management of groundwater resources and cognizance of seawater intrusion in coastal aquifers.

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Won, Byeongho, Se-Yeong Hamm, Kue-Young Kim, Kyoochul Ha, Jehyun Shin, Seho Hwang, and Soo-Hyoung Lee. "Response Analysis of Multi-Layered Volcanic Aquifers in Jeju Island to the 2011 M9.0 Tohoku-Oki Earthquake." Water 11, no. 5 (May 5, 2019): 942. http://dx.doi.org/10.3390/w11050942.

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Seismic waves caused by earthquakes can lead to the movement of fresh groundwater and saltwater in coastal aquifers. The groundwater level, temperature, and electrical conductivity in coastal monitoring wells on the volcanic island of Jeju all responded to the 2011 M 9.0 Tohoku-Oki earthquake. As a result of the earthquake, groundwater temperature and electrical conductivity patterns demonstrated freshwater outflow and saltwater inflow through the monitoring wells in multi-layered coastal aquifers. The seismicity also affected the behavior of ocean tides occurring at depth along the multi-layered coastal aquifers. These observations prove that the use of multi-depth systems for monitoring groundwater level, temperature, and electrical conductivity are more effective than single monitoring systems for understanding the exact behavior of multi-layered aquifers as well as efficiently detecting earthquake-induced or anthropogenic impacts on aquifers in coastal, karstic, or volcanic areas.

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Zahid, Anwar, Farhana Islam, M. Rashidul Hassan, Kamrul Islam, and Nur Ahmed. "Analysis of Aquifer Pumping Test Data to Determine Deep Groundwater Security in Southeastern Bangladesh." Journal of Natural Resources and Development 8 (December 1, 2018): 125–43. http://dx.doi.org/10.5027/jnrd.v8i0.12.

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In southeastern Bangladesh, where water quality in the upper aquifers is a serious constraint, future development will likely be confined to deep fresh groundwater. Owing to the importance and pervasive use of deep groundwater, the sustainability of water use has received extensive attention. However, excessive extraction from deep aquifers may pose a threat to the storage as well as the quality of water due to the high susceptibility to salinization and arsenic contamination from upper aquifers. Hence, determining the extension of aquifer units and the characterizing aquifer sediments are very important to ensure sustainable development and management of limited fresh groundwater resources. The study area extends over six districts of the southeastern coastal region of Bangladesh. In order to assess and monitor deep fresh groundwater potential in the study area, aquifer pumping tests were performed at six locations with up to 72 h of constant-discharge prior to recovery. Different methods were used to analyze the drawdown and recovery data considering aquifers as confined or leaky-confined. Based on transmissivity values it was found that the studied deep aquifers have moderate to high potential for potable water supply. However, this deep fresh groundwater may not be safe for a longer period where upper aquifer units contain saline groundwater and where there is no significant aquitard encountered above or below the deep aquifer. Irrigation extraction of the deep groundwater is not recommended.

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Sherif, M. M., and V. P. Singh. "Effect of Groundwater Pumping on Seawater Intrusion in Coastal Aquifers." Journal of Agricultural and Marine Sciences [JAMS] 7, no. 2 (June 1, 2002): 61. http://dx.doi.org/10.24200/jams.vol7iss2pp61-67.

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Many aquifers around the globe are located in coastal areas and are thus subjected to the seawater intrusion phenomenon. The growth of population in coastal areas and the conjugate increase in human, agricultural, and industrial activities have imposed an increasing demand for freshwater. This increase in water demand is often covered by extensive pumping of fresh groundwater, causing subsequent lowering of the water table (or piezometric head) and upsetting the dynamic balance between freshwater and saline water bodies. The classical result of such a development is seawater intrusion. This paper presents a review for the seawater intrusion phenomenon in coastal aquifers. The effect of pumping activities on the seawater intrusion in the Nile Delta aquifer of Egypt is investigated. It was concluded that any additional pumping should be located in the middle Delta and avoided in the eastern and western sides of the Delta.

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Khublaryan, M. G., A. P. Frolov, and I. O. Yushmanov. "Seawater intrusion into coastal aquifers." Water Resources 35, no. 3 (May 2008): 274–86. http://dx.doi.org/10.1134/s0097807808030032.

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Post, Vincent E. A., Alexander Vandenbohede, Adrian D. Werner, Maimun, and Michael D. Teubner. "Groundwater ages in coastal aquifers." Advances in Water Resources 57 (July 2013): 1–11. http://dx.doi.org/10.1016/j.advwatres.2013.03.011.

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Monnin, Christophe, Joseph Tamborski, Simon Bejannin, Marc Souhaut, Manon Roques, Philippe Olivier, and Pieter van Beek. "Freshening of a Coastal Karst Aquifer Revealed by the Temporal Changes in a Spring Water Composition (La Palme, Southern France)." Hydrology 6, no. 2 (June 3, 2019): 45. http://dx.doi.org/10.3390/hydrology6020045.

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Coastal karst aquifers are vulnerable to sea level rise and seawater intrusion. Knowledge of aquifer hydrological characteristics is therefore essential to managing this water resource. Long-term aquifer monitoring may not always be possible, especially in areas that humans frequent for recreational purposes. However, hydrological information can be deduced from the chemical composition of periodically sampled groundwaters. We characterized the complete chemical composition (temperature, pH, salinity, ORP, O2, Na-K-Ca-Mg-Ba-Sr-Si-Cl-SO4-DIC, and DOC) of a brackish karstic spring located along the French Mediterranean coast (La Palme). The salinity of the spring water varied between 4 and 9 during the 2.5 year period of observation. Chemical analyses revealed that the spring is modified from modern seawater, as shown by Na-normalized dissolved element concentrations. Thermodynamic calculations of mineral saturation states (PHREEQC) point to aragonite and barite saturation and elevated equilibrium CO2 partial pressure. The simultaneous salinity minima and oxygen maxima coincide with extreme values of dissolved element concentrations. This indicates that variation in salinity and water chemistry in La Palme coastal aquifer is primarily driven by infiltration of fresh rainwater. This study shows that geochemical investigations can provide an alternative approach to characterizing the hydrological properties of coastal karst aquifers when wells or boreholes are not readily available.

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Zepeda Quintana, David Slim, Claudia Mariana Loeza Rentería, Nora Elba Munguía Vega, Javier Esquer Peralta, and Luis Eduardo Velazquez Contreras. "Sustainability strategies for coastal aquifers: A case study of the Hermosillo Coast aquifer." Journal of Cleaner Production 195 (September 2018): 1170–82. http://dx.doi.org/10.1016/j.jclepro.2018.05.191.

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Chuang, M. H., C. S. Huang, G. H. Li, and H. D. Yeh. "Groundwater fluctuations in heterogeneous coastal leaky aquifer systems." Hydrology and Earth System Sciences 14, no. 10 (October 11, 2010): 1819–26. http://dx.doi.org/10.5194/hess-14-1819-2010.

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Abstract. In the past, the coastal leaky aquifer system, including two aquifers and an aquitard between them, was commonly assumed to be homogeneous and of infinite extent in the horizontal direction. The leaky aquifer system may however be heterogeneous and of finite extent due to variations in depositional and post depositional processes. In this paper, the leaky aquifer system is divided into several horizontal regions for the heterogeneous aquitard and underlying aquifer. A one-dimensional analytical model is developed for describing the head fluctuation in such a heterogeneous leaky aquifer system. The hydraulic head of the upper unconfined aquifer is assumed constant. It is found that both the length and location of the discontinuous aquitards presented in the coastal area have significant effects on the amplitude and phase shift of the head fluctuation in the lower aquifer. In addition, the influence of the formation heterogeneity on the spatial head distribution is also investigated.

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Gottschalk, Ian, Rosemary Knight, Theodore Asch, Jared Abraham, and James Cannia. "Using an airborne electromagnetic method to map saltwater intrusion in the northern Salinas Valley, California." GEOPHYSICS 85, no. 4 (June 15, 2020): B119—B131. http://dx.doi.org/10.1190/geo2019-0272.1.

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Saltwater intrusion can pose a serious threat to groundwater quality in coastal regions. Estimating the extent of saltwater intrusion is vital for groundwater managers to plan appropriate mitigation strategies. The airborne electromagnetic (AEM) method is commonly used to evaluate groundwater resources, but it is challenging to apply in coastal environments because the low resistivity of saltwater-saturated aquifers attenuates the electromagnetic signal quickly and the relationship between electrical resistivity and pore water salinity is complex. However, if successful, the AEM method can supply information to address questions of critical importance in coastal regions. We investigated the extent of, and controls on, saltwater intrusion using the AEM method in the northern Salinas Valley, CA, USA. We collected 635 line-km of AEM data in the study area, the inversion results of which produced estimates of the electrical resistivity of the subsurface, reaching depths of between 50 and approximately 200 m below the ground surface. We have developed a relationship between the AEM electrical resistivity model and groundwater salinity, calibrated from borehole geophysical and water quality measurements, which allowed us to generate images revealing the distribution of saltwater and fresher groundwater in the study area. This fresher groundwater (defined as “a source of drinking water”) was successfully mapped out in the unconfined aquifer (the Dune Sand Aquifer) and the uppermost confined aquifer (the 180-Foot Aquifer) in the study area, illustrating a groundwater recharge process that helps mitigate saltwater intrusion in the 180-Foot Aquifer. Deep, low-resistivity bodies also were mapped, indicating regions where saltwater likely is migrating vertically from the 180-Foot Aquifer into the lower confined aquifer (the 400-Foot Aquifer). The findings from this case study demonstrate the value of acquiring AEM data for investigating the distribution of salinity in coastal aquifers impacted by saltwater intrusion.

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Carrión-Mero, Paúl, F. Javier Montalván, Fernando Morante-Carballo, Carolina Loor-Flores de Valgas, Boris Apolo-Masache, and Javier Heredia. "Flow and Transport Numerical Model of a Coastal Aquifer Based on the Hydraulic Importance of a Dyke and Its Impact on Water Quality. Manglaralto—Ecuador." Water 13, no. 4 (February 8, 2021): 443. http://dx.doi.org/10.3390/w13040443.

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Coastal aquifers are part of the natural resources contributing to local development and promote resilience in the most vulnerable communities near the sea. Manglaralto, an Ecuadorian coastal parish, is affected by water resource scarcity. The increase in salinity and deterioration of the water quality is generated by the local and floating population’s demand, causing an increase in the Total Dissolved Solids (TDS) concentrations and decreasing the aquifer’s piezometric levels. The aim is to establish a numerical model of flow and transport of the Manglaralto coastal aquifer by using hydrogeological data and Visual Transin software, relating the hydraulic importance of a dyke’s design (“tape”) and its impact on the quality of the water. The methodology is (i) hydrogeological database analysis, (ii) the system’s recharge concerning the soil water balance, (iii) the boundary conditions of the flow and transport model and, (iv) the results and validation of the numerical simulation. The results configure the importance of the coastal aquifer’s artificial recharge in the area where the tape is located, as reflected in the increase in piezometric levels and the decrease in salinity in wells near the sea. In conclusion, the numerical model of flow and transport allows expanding the knowledge of the variation of the piezometric levels and TDS concentrations over time, the importance of recharge in the hydrogeological system’s operation, and correct community management resilience and projection to sustainable development.

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Widada, Sugeng, Baskoro Rochaddi, Chrisna Adhi Suryono, and Irwani Irwani. "Intrusi Air Laut di Pesisir Tugu Kota Semarang Berdasarkan Resistiviti dan Hidrokimia." Jurnal Kelautan Tropis 21, no. 2 (December 7, 2018): 75. http://dx.doi.org/10.14710/jkt.v21i2.3610.

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Sea Water Intrusion in Tugu Coastal Area of Semarang City Based on Resistivity and Hydrochemical Tugu Coastal Area is one of the coastal areas in Semarang City, Central Java Province that continues to grow. Although the clean water network from the Local Water Supply Utility is available, groundwater is still used to meet the water needs of the community. Some of the groundwater in the area is brackish to salty conditions as the result of sea water intrusion process. The research aims to determine configuration of aquifers which have been intruded with sea water in Tugu Coastal Area, Semarang City, so that groundwater exploitation from the aquifer can be avoided. The method used in this study was descriptive analysis, in which the condition of aquifers was based on interpretation of resistivity data. Simple hydrochemical facies analysis using the Trilinier Piper Diagram method is carried out to detect sea water intrusion. The results of the study indicated that aquifers in the Coastal area consisted of several layers. Aquifer which has been intruded with seawater is located on the north side of the Semarang - Kendal highway, both for confined and unconfined aquifers. The depth of confined aquifer which is intruded by sea water reaches 50 - 75 m below the local land surface. While the unconfined aquifer depth is up to a depth of 6 m below the local land surface. Wilayah Pesisir Tugu, Kota Semarang, Provinsi Jawa Tengah merupakan salah satu daerah pesisir di Kota Semarang yang terus berkembang. Meskipun jaringan air bersih dari Perusahaan Daerah Air Minum telah tersedia, namun pemanfaatan air tanah masih digunakan untuk memenuhi kebutuhan air bagi masyarakat. Sebagian air tanah di daerah tersebut dalam kondisi payau hingga asin yang diduga akibat proses intrusi air laut.. Penelitian ini bertujuan untuk mengetahui konfigurasi akuifer yang telah terintrusi air laut Wilayah Pesisir Tugu, Kota Semarang, sehingga dapat dihindari pengambilan air tanah dari akuifer tersebut. Metode penelitian yang digunakan dalam penelitian ini adalah diskriptis analisis untuk menggambarkan kondisi akuifer berdasarkan hasil interpretasi data geolistrik resistiviti. Analisa fasies hidrokimia secara sederhana dengan metode Diagram Triliner Piper dilakukan untuk mendeteksi adanya intrusi air laut. Hasil penelitian menujukan bahwa akuifer di daerah Pesisir Tugu terdiri dari beberapa lapisan. Akuifer yang telah terintrusi air laut adalah yang berada di sebelah utara jalan raya Semarang – Kendal, baik untuk akuier bebas maupun akuifer tertekan. Kedalaman akuifer tertekan yang terintrusi adalah hingga mencapai 50 sampai dengan 75 m di bawah muka tanah setempat. Sedangkan kedalaman akuifer bebasnya berada hingga kedalaman 6 m di bawah muka tanah setempat

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Armanuos, Asaad M., Nadhir Al-Ansari, and Zaher Mundher Yaseen. "Assessing the Effectiveness of Using Recharge Wells for Controlling the Saltwater Intrusion in Unconfined Coastal Aquifers with Sloping Beds: Numerical Study." Sustainability 12, no. 7 (March 29, 2020): 2685. http://dx.doi.org/10.3390/su12072685.

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Groundwater systems are considered major freshwater sources for many coastal aquifers worldwide. Seawater intrusion (SWI) inland into freshwater coastal aquifers is a common environmental problem that causes deterioration of the groundwater quality. This research investigates the effectiveness of using an injection through a well to mitigate the SWI in sloping beds of unconfined coastal aquifers. The interface was simulated using SEAWAT code. The repulsion ratios due to the length of the SWI wedge (RL) and the area of the saltwater wedge (RA) were computed. A sensitivity analysis was conducted to recognize the change in the confining layer bed slope (horizontal, positive, and negative) and hydraulic parameters of the value of the SWI repulsion ratio. Injection at the toe itself achieved higher repulsion ratios. RL and RA declined if the injection point was located remotely and higher than the toe of the seawater wedge. Installation at the toe achieved a higher RL in positive sloping followed by horizontal and negative slopes. Moreover, the highest value of RA could be reached by injecting at the toe itself with a horizontal bed aquifer, followed by negative and positive slopes. The recharge well is confirmed as one of the most effective applications for the mitigation of SWI in sloping bed aquifers. The Akrotiri case study shows that the proposed recharging water method has a significant impact on controlling SWI and declines in both SWI wedge length and area.

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Cherubini, C., and N. Pastore. "Critical stress scenarios for a coastal aquifer in southeastern Italy." Natural Hazards and Earth System Sciences 11, no. 5 (May 16, 2011): 1381–93. http://dx.doi.org/10.5194/nhess-11-1381-2011.

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Abstract. Over the last years the sustainable management of coastal water resources has become strategic, especially in southern Salento Peninsula (Apulia), where mal-performing management strategies adopted, together with the vulnerability of the hydrogeological system, have given rise to the deterioration of groundwater quality due to saltwater intrusion. In the study area there is the presence of multilevel shallow aquifer and a deep aquifer that interact by means of faults. The geological system is highly vulnerable to seawater intrusion so there is the need to adopt management strategies to avoid seawater intrusion phenomena. Nevertheless there is a lack of studies that analyze the methodology for the correct exploitation if the water resource in order to avoid further intrusion phenomena. This paper combines a density-driven, flow numerical model (Seawat v.4) with a fault conceptual and hydrologic model to simulate saltwater intrusion phenomenon in the deep as well as in the shallow aquifer of the Salento area. By means of the individuation of an indicator parameter of groundwater quality, it has been possible to simulate different scenarios of exploitation and therefore to define critical stress scenarios for both aquifers. The results show that the deep aquifer is more vulnerable than the shallow one, which means that in the former, in order not to reach conditions of contamination, a lower density of wells is necessary than in the latter. The reduction of well density coupled with the artificial recharge of freshwater into the aquifer may be proposed as a solution strategy to protect the aquifer. Therefore, future developments of the present study will be represented by the simulation of different scenarios of recharging to inhibit the saltwater intrusion front further inland. The proposed methodology and its future developments can represent an empirical tool to provide preliminary guidelines for long-term groundwater management in coastal aquifers.

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McDougall, Andrew, Sharon Marshall, and Tom Espinoza. "Determining groundwater dependence of the Cooloola Patterned Fens in south-eastern Queensland, and threats posed by groundwater extraction." Marine and Freshwater Research 68, no. 12 (2017): 2336. http://dx.doi.org/10.1071/mf16424.

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Water extraction from the local aquifer and streams for water supply in the Cooloola area of south-eastern Queensland threatens the groundwater flow for an iconic groundwater-dependent ecosystem, the Cooloola Patterned Fens. Water-chemistry samples were collected from within the fens wetland, bores and local streams. The multivariate techniques of hierarchical cluster analysis (HCA), principal component analysis (PCA) and multidimensional scaling (MDS) were used to discriminate aquifer source of water. Water chemistry of the patterned fens complex was associated with perched aquifers atop an underlying peat aquitard, whereas the water chemistry of two nearby creek systems (Searys Creek and Teewah Creek) was more closely associated with the regional aquifer. The present study highlighted the need for better understanding of the hydrogeology of coastal aquifers and the ecosystems dependent on them.

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Zamrsky, Daniel, Gualbert H. P. Oude Essink, and Marc F. P. Bierkens. "Estimating the thickness of unconsolidated coastal aquifers along the global coastline." Earth System Science Data 10, no. 3 (September 3, 2018): 1591–603. http://dx.doi.org/10.5194/essd-10-1591-2018.

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Abstract. Knowledge of aquifer thickness is crucial for setting up numerical groundwater flow models to support groundwater resource management and control. Fresh groundwater reserves in coastal aquifers are particularly under threat of salinization and depletion as a result of climate change, sea-level rise, and excessive groundwater withdrawal under urbanization. To correctly assess the possible impacts of these pressures we need better information about subsurface conditions in coastal zones. Here, we propose a method that combines available global datasets to estimate, along the global coastline, the aquifer thickness in areas formed by unconsolidated sediments. To validate our final estimation results, we collected both borehole and literature data. Additionally, we performed a numerical modelling study to evaluate the effects of varying aquifer thickness and geological complexity on simulated saltwater intrusion. The results show that our aquifer thickness estimates can indeed be used for regional-scale groundwater flow modelling but that for local assessments additional geological information should be included. The final dataset has been made publicly available (https://doi.pangaea.de/10.1594/PANGAEA.880771).

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Siena, Martina, and Monica Riva. "Groundwater withdrawal in randomly heterogeneous coastal aquifers." Hydrology and Earth System Sciences 22, no. 5 (May 18, 2018): 2971–85. http://dx.doi.org/10.5194/hess-22-2971-2018.

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Abstract. We analyze the combined effects of aquifer heterogeneity and pumping operations on seawater intrusion (SWI), a phenomenon which is threatening coastal aquifers worldwide. Our investigation is set within a probabilistic framework and relies on a numerical Monte Carlo approach targeting transient variable-density flow and solute transport in a three-dimensional randomly heterogeneous porous domain. The geological setting is patterned after the Argentona river basin, in the Maresme region of Catalonia (Spain). Our numerical study is concerned with exploring the effects of (a) random heterogeneity of the domain on SWI in combination with (b) a variety of groundwater withdrawal schemes. The latter have been designed by varying the screen location along the vertical direction and the distance of the wellbore from the coastline and from the location of the freshwater–saltwater mixing zone which is in place prior to pumping. For each random realization of the aquifer permeability field and for each pumping scheme, a quantitative depiction of SWI phenomena is inferred from an original set of metrics characterizing (a) the inland penetration of the saltwater wedge and (b) the width of the mixing zone across the whole three-dimensional system. Our results indicate that the stochastic nature of the system heterogeneity significantly affects the statistical description of the main features of the seawater wedge either in the presence or in the absence of pumping, yielding a general reduction of toe penetration and an increase of the width of the mixing zone. Simultaneous extraction of fresh and saltwater from two screens along the same wellbore located, prior to pumping, within the freshwater–saltwater mixing zone is effective in limiting SWI in the context of groundwater resources exploitation.

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Youngs, E. G. "Maintaining Fresh-Water Aquifers Over Saline Water in Coastal Aquifers." Journal of Agricultural and Marine Sciences [JAMS] 7, no. 2 (June 1, 2002): 23. http://dx.doi.org/10.24200/jams.vol7iss2pp23-28.

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Seepage analysis is used to investigate the location dependence of fresh-water inputs and outputs in maintaining the depth of the fresh water over the saline water intruding from the sea in coastal aquifers in steady state conditions. Examples are given that show that maximum depths occur when the inputs are in the vicinity of the watershed and the outputs are near the coast.

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EL Hamidi, Mohamed Jalal, Abdelkader Larabi, and Mohamed Faouzi. "Numerical Modeling of Saltwater Intrusion in the Rmel-Oulad Ogbane Coastal Aquifer (Larache, Morocco) in the Climate Change and Sea-Level Rise Context (2040)." Water 13, no. 16 (August 7, 2021): 2167. http://dx.doi.org/10.3390/w13162167.

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Many coastal aquifers have experienced seawater intrusion (SWI) into fresh groundwater aquifers. The principal causes of SWI include over-pumping and events such as climate change (CC) and rising sea levels. In northern Morocco, the Rmel-Oulad Ogbane coastal aquifer (ROOCA) supplies high-quality groundwater for drinking water and agriculture. This favorable situation has led to increased pumping, resulting in environmental challenges such as dropping water table and SWI. Furthermore, the climate has resulted in less recharge, with an estimated annual precipitation of 602 mm and an average temperature of 18.5 °C. The goal of this study is to determine how CC, over-pumping, and sea-level rise (SLR) affect SWI. Computational groundwater and solute transport models are used to simulate the spatial and temporal evolution of hydraulic heads and groundwater solute concentrations. The calibration is based on steady and transient groundwater levels from 1962 to 2040. SWI simulations show that the NW sector of the coastal area would be polluted, with the toe reaching 5.2 km inland with a significant salinity (15–25 g/L). To protect the fresh water in the reservoir from SWI, enhanced groundwater development and management approaches for this aquifer are required, such as artificial recharge from surface water.

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Roy, Dilip Kumar, and Bithin Datta. "Trained meta-models and evolutionary algorithm based multi-objective management of coastal aquifers under parameter uncertainty." Journal of Hydroinformatics 20, no. 6 (July 11, 2018): 1247–67. http://dx.doi.org/10.2166/hydro.2018.087.

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Abstract Meta-model based coupled simulation-optimization methodology is an effective tool in developing sustainable saltwater intrusion management strategies for coastal aquifers. Such management strategies largely depend on the accuracy, reliability, and computational feasibility of meta-models and the numerical simulation model. However, groundwater models are associated with a certain amount of uncertainties, e.g. parameter uncertainty and uncertainty in prediction. This study addresses uncertainties related to input parameters of the groundwater flow and transport system by using a set of randomized input parameters. Three meta-models are compared to characterize responses of water quality in coastal aquifers due to groundwater extraction patterns under parameter uncertainty. The ensemble of the best meta-model is then coupled with a multi-objective optimization algorithm to develop a saltwater intrusion management model. Uncertainties in hydraulic conductivity, compressibility, bulk density, and aquifer recharge are incorporated in the proposed approach. These uncertainties in the physical system are captured by the meta-models whereas the prediction uncertainties of meta-models are further addressed by the ensemble approach. An illustrative multi-layered coastal aquifer system is used to demonstrate the feasibility of the proposed approach. Evaluation results indicate the capability of the proposed approach to develop accurate and reliable management strategies for groundwater extraction to control saltwater intrusion.

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Pandian, Rajaveni Sundara, Indu Sumadevi Nair, and Elango Lakshmanan. "Finite element modelling of a heavily exploited coastal aquifer for assessing the response of groundwater level to the changes in pumping and rainfall variation due to climate change." Hydrology Research 47, no. 1 (May 16, 2015): 42–60. http://dx.doi.org/10.2166/nh.2015.211.

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Coastal aquifers are always under threat of seawater intrusion due to over-extraction of groundwater. The objective here is to assess aquifer response to variation in pumping and rainfall recharge due to projected climate change by groundwater modelling in a heavily exploited aquifer. Finite element groundwater flow modelling was carried out from March 1988 to December 2030 using FEFLOW software. Steady state calibration was done to match observed and simulated groundwater head by varying aquifer parameters within the allowable range. Transient state calibration was carried out during the period March 1988 to December 2002. The calibrated model was validated by comparing the simulated and observed groundwater head from January 2003 to December 2012. Groundwater head was predicted for a period until 2030 under eight different scenarios of changes in pumping and rainfall recharge. This prediction indicated that 10% increase of recharge and 10% decrease of pumping causes 3 m and 6 m increase in groundwater head in upper and lower aquifers, respectively, by the end of 2030. Groundwater recharge can be increased by rejuvenation of existing surface water bodies, check dams and construction of proposed check dams. Thus, increase of groundwater recharge and decrease in well field pumping is achievable to restore this heavily exploited coastal aquifer in another 20 years.

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Chen, K. P., and J. J. Jiao. "Seawater intrusion and aquifer freshening near reclaimed coastal area of Shenzhen." Water Supply 7, no. 2 (July 1, 2007): 137–45. http://dx.doi.org/10.2166/ws.2007.048.

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Local groundwater in coastal aquifers in Shenzhen has experienced heavy pumping since the 1980s when it began to expand very quickly from a fishing village to a modern city. Meanwhile, large-scale land reclamation was carried out to meet the needs of various urbanization projects. In this paper we analyzed the groundwater from a coastal aquifer system in Shenzhen and examined the evolution of groundwater chemistry over the last 20 years. The temporal changes of ionic ratios of rCa/(rHCO3 + rSO4) and the relationship between sodium and chloride in the coastal area over this period indicate that the aquifer experienced seawater intrusion in the 1980s but underwent gradual freshening in the 1990s. It is speculated that seawater intrusion was induced by excessive groundwater pumping and that the aquifer freshening was caused both by the recent reduction in groundwater pumping and by coastal reclamation which moved the interface between fresh groundwater and saline groundwater seaward.

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Fidelibus, Maria, and Antonio Pulido-Bosch. "Groundwater Temperature as an Indicator of the Vulnerability of Karst Coastal Aquifers." Geosciences 9, no. 1 (December 30, 2018): 23. http://dx.doi.org/10.3390/geosciences9010023.

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Coastal karst aquifers show a three-dimensional vulnerability, which consists of the whole of the “intrinsic vulnerability” and the “groundwater vulnerability to seawater intrusion”. The results of a study carried out in the Salento karst coastal aquifer (southern Italy) show that temperature, as well as being a reliable tracer of groundwater flow, is also an effective indicator of vulnerability in anisotropic media. The trend of isotherms related to a cross-section of the aquifer thermal field, combined with geological, geomorphological, and hydrogeological information, allows the role of faults and dolines in the mass transport from ground surface to be inferred. Isotherm trends may also give information on the permeability distribution along faults. A specific temperature value evidence the saltwater top, thus indicating the groundwater vulnerability to salinization.

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Βουδούρης, K., K. Νίκας, and A. Αντωνάκος. "STUDY OF EVOLUTION OF THE SEAWATER INTRUSION IN COASTAL AQUIFERS. CASE STUDY: THE COASTAL AQUIFER SYSTEM OF NW ACHAIA." Bulletin of the Geological Society of Greece 36, no. 4 (January 1, 2004): 1952. http://dx.doi.org/10.12681/bgsg.16690.

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Seawater intrusion problems are recorded in coastal aquifers, which constitute the main sources of drinking water and agricultural irrigation in many countries. The aim of this work is to describe the evolution of the salinity distribution by seawater intrusion, based on results from chemical analyses, of 29 groundwater samples in the NWAchaia area (Peloponnesus, Greece). The study of these data indicates that aquifer waters in large part of area reflect salinization related to seawater intrusion. The occurrence of Ca-CI hydrochemical types of groundwater indicates active seawater intrusion. Cation exchange is the most noticeable hydrogeochemical process in the movement of the saline front in the coastal aquifer. Geographical distribution of Careact index was mapped. The areas with advance or decline of the seawater intrusion front are defined from this map.

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Makokha, Mary, Akira Kobayashi, and Shigeyasu Aoyama. "Effect of Tidal Fluctuation on Velocity Distribution in Coastal Aquifers." Journal of Rainwater Catchment Systems 13, no. 2 (2008): 1–6. http://dx.doi.org/10.7132/jrcsa.kj00004871194.

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Hussain, Mohammed S., Hany F. Abd-Elhamid, Akbar A. Javadi, and Mohsen M. Sherif. "Management of Seawater Intrusion in Coastal Aquifers: A Review." Water 11, no. 12 (November 24, 2019): 2467. http://dx.doi.org/10.3390/w11122467.

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Seawater intrusion (SWI) is one of the most challenging and widespread environmental problems that threaten the quality and sustainability of fresh groundwater resources in coastal aquifers. The excessive pumping of groundwater, associated with the lack of natural recharge, has exacerbated the SWI problem in arid and semi-arid regions. Therefore, appropriate management strategies should be implemented in coastal aquifers to control the impacts of SWI problems, considering acceptable limits of economic and environmental costs. The management of coastal aquifers involves the identification of an acceptable ultimate landward extent of the saline water body and the calculation of the amount of seaward discharge of freshwater that is necessary to keep the saline–freshwater interface in a seacoast position. This paper presents a comprehensive review of available hydraulic and physical management strategies that can be used to reduce and control SWI in coastal aquifers. Advantages and disadvantages of the different approaches are presented and discussed.

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Abd-Elaty, Ismail, Hany Farhat Abd Elhamid, and Akbar Javadi. "Numerical analysis of the effects of changing hydraulic parameters on saltwater intrusion in coastal aquifers." Engineering Computations 33, no. 8 (November 7, 2016): 2546–64. http://dx.doi.org/10.1108/ec-11-2015-0342.

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Purpose The purpose of this paper is to develop and validate a numerical model to study the effect of changing hydraulic parameters on saltwater intrusion in coastal aquifers. Design/methodology/approach The numerical model SEAWAT is validated and applied to a hypothetical case (Henry problem) and a real case study (Biscayne aquifer, Florida, USA) for different values of hydraulic parameters including; hydraulic conductivity, porosity, dispersion, diffusion, fluid density and solute concentration. The dimensional analysis technique is used to correlate these parameters with the intrusion length. Findings The results show that the hydraulic parameters have a clear effect on saltwater intrusion as they increase the intrusion in some cases and decrease it in some other cases. The results indicate that changing hydraulic parameters may be used as a control method to protect coastal aquifers from saltwater intrusion. Practical implications The results of the application of the model to the Biscayne aquifer in Florida showed that the intrusion can be reduced to 50 percent when the hydraulic conductivity is reduced to 50 percent. Decreasing hydraulic conductivity by injecting some relatively cheap materials such as bentonite can help to reduce the intrusion of saltwater. So the saltwater intrusion can be reduced with relatively low cost through changing some hydraulic parameters. Originality/value A relationship to calculate intrusion length in coastal aquifer is developed and the impact of different hydraulic parameters on saltwater intrusion is highlighted. Control of saltwater intrusion using relatively cheap method is presented.

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Ferguson, Grant, and Tom Gleeson. "Reply to 'Threats to coastal aquifers'." Nature Climate Change 3, no. 7 (June 25, 2013): 605–6. http://dx.doi.org/10.1038/nclimate1930.

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Sanford, Ward E., and Leonard F. Konikow. "Porosity development in coastal carbonate aquifers." Geology 17, no. 3 (1989): 249. http://dx.doi.org/10.1130/0091-7613(1989)017<0249:pdicca>2.3.co;2.

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Sindhu, G., M. Ashith, P. G. Jairaj, and Rajesh Raghunath. "Modelling of Coastal Aquifers of Trivandrum." Procedia Engineering 38 (2012): 3434–48. http://dx.doi.org/10.1016/j.proeng.2012.06.397.

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Manzano, M., E. Custodio, H. Loosli, M. C. Cabrera, X. Riera, and J. Custodio. "Palaeowater in coastal aquifers of Spain." Geological Society, London, Special Publications 189, no. 1 (2001): 107–38. http://dx.doi.org/10.1144/gsl.sp.2001.189.01.08.

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Lathashri, U. A., and A. Mahesha. "Groundwater sustainability assessment in coastal aquifers." Journal of Earth System Science 125, no. 6 (August 2016): 1103–18. http://dx.doi.org/10.1007/s12040-016-0719-5.

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Journal articles on the topic 'Coastal aquifers'

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