Seawater Intrusion Research Articles

A Scoping Review on Understanding Climate Change’s Effects on Pregnancy in Coastal Regions

Introduction: Pregnancy increases vulnerability to environmental stressors. Climate change heightens risks for pregnant women, leading to adverse maternal and infant outcomes. Coastal regions, prone to sea-level rise, rising temperatures, saltwater intrusion, and extreme weather, face significant health impacts. This review summarises the effects of climate change on pregnant women in these areas, emphasising the need for targeted interventions to mitigate these risks. Discussion: This scoping review was conducted using the advanced Arksey and O’Malley framework. Utilizing several keywords, including 'climate change,' 'adverse pregnancy,' 'pregnant outcome,' 'coastal,' and 'island,' a thorough exploration was conducted on PubMed, ScienceDirect, Scopus and ProQuest. A thorough review of 660 articles from 2020–2024 on those online databases identified 34 relevant studies. The findings show that coastal residents face environmental challenges such as rising temperatures, air pollution, cyclones, hurricanes, ozone exposure, floods, and highly saline water. Prolonged exposure to these conditions exacerbates health risks. Climate change is linked to adverse pregnancy outcomes, including low birth weight, small gestational age, stillbirth, preterm birth, neonatal health problems, and increased the risk of pregnancy complications and miscarriages. Conclusion: Climate change significantly affects pregnant women, causing complications and adverse outcomes throughout pregnancy. Addressing these issues requires comprehensive policies and intervention programs. These insights provide a foundation for policymakers to develop strategies that support and protect pregnant women in vulnerable regions. Household-level efforts, such as providing a comfortable living environment, can help reduce the climate change impacts.

Perceived Impacts of Climate Change on Coastal Aquaculture in the Cyclone Prone Southwest Region of Bangladesh

The southwest region of Bangladesh is particularly vulnerable to a range of climatic threats, including cyclones, prolonged flooding, sea level rise, saltwater intrusion, drought, and riverbank erosion. The study investigates how these different drivers affect aquaculture systems and aims to provide critical insights for sustainable management. The survey work focused on the problems, vulnerabilities, migration, and adaptive strategies of communities of the southwest region of Bangladesh, that rely heavily on shrimp, fish, and crab production for their livelihoods. Data were collected from the 80 respondents across four unions (Atulia, Burigoalini, Gabura, and Bhurulia) in Shyannagar Upazila, Satkhira District, using a structured questionnaire survey and focus group discussions. Findings reveal that climate change events have significantly changed shrimp farming in enclosures, pond aquaculture, and crab point management, and negatively impacted livelihoods. Pond aquaculture appeared to be the most vulnerable to climate change conditions, followed by shrimp farming in enclosures and crab points. Furthermore, the adverse effects of climate change compelled human migration within the study area, primarily driven by the search for employment. This study provides evidence of the effects of various climate change stressors on shrimp, fish, and crab production systems and the adaptive difficulties of the communities dependent on aquatic ecosystems. As the natural calamity like cyclone cannot be prevented, understanding the impact of previous events may help people of the affected area as well as the policy makers to plan for better survival.

Temporal gravimetry, campaign and permanent GNSS, and interferometric radar techniques: A comparative approach to quantifying land deformation rates in coastal Texas

Land subsidence and local sea-level rise are well-known on-going hazards that negatively impacting coastal regions, exacerbating coastal flooding, threatening infrastructure stability, accelerating erosion, and amplifying the risks of inundation and property damage. This study used four techniques to quantify land deformation rates in the Texas Coastal Bend region and to investigate the controlling factors on two different spatiotemporal scales: (1) local scale, where biweekly temporal gravity and campaign Global Navigation Satellite System (GNSS) measurements were acquired at six locations over 2 years (October 2020–September 2022); and (2) regional scale, where vertical displacement time series were extracted from the Interferometric Synthetic Aperture Radar (InSAR) and 15 permanent GNSS stations over 5 years (January 2017–November 2021). The observed inconsistency between land deformation rates derived from gravity (range: −33.32 ± 149.30 to +338.68 ± 107.93 mm/yr) and campaign GNSS (range: −17.91 ± 14.90 to +5.69 ± 9.93 mm/yr) surveys could be attributed to the short campaign period and the infrequency of data acquisition. The InSAR-derived deformation rates (range: −12.16 ± 0.12 to +11.70 ± 0.00 mm/yr) were consistent with the permanent GNSS-derived rates (range: −14.0 ± 0.6 to +9.0 ± 3.0 mm/yr); both indicated spatiotemporal variability in land deformation rates across the Texas Coastal Bend. A total of 4 coastal towns (−2.3 ± 3.3 mm/yr), 3 cities (−1.4 ± 2.6 mm/yr), 3 inland towns (−3.6 ± 4.2 mm/yr), and 7 industrial plants (−3.8 ± 5.8 mm/yr) were found to have significant land subsidence rates due to sediment compaction, growth faulting, oil/gas extraction, and groundwater extraction. Results of this study emphasize the advantages and limitations of four different techniques in quantifying land deformation rates; can enhance estimates of local sea-level rise; and offer valuable insights to support coastal communities in mitigating the impacts of land subsidence and improving their resilience.

PERHITUNGAN AWAL IMBUHAN AIRTANAH ALAMI DAERAH ALIRAN SUNGAI CIKAPUNDUNG-GANDOK (KAJIAN PERBANDINGAN)

Groundwater recharge is a crucial factor in determining the permissible groundwater extraction within a watershed. In the Cikapundung watershed, the contribution of groundwater to raw water supply has been continuously declining, prompting a shift from groundwater to surface water usage. This study aims to quantify the groundwater recharge volume and recharge coefficient for each geological formation within the Cikapundung-Gandok watershed, covering an area of 90.4 km², and to compare the results with previous studies. The analysis estimates recharge volumes based on rainfall data from 8 stations around the Cikapundung-Gandok watershed from 2010 to 2019, geological formation data, and alternative recharge coefficients. The difference in recharge volume from previous studies is 393,348 m³/year or 1%. Two formations, Qvu and Qyu, which were not identified in earlier studies, supplement the existing geological dataset. The selected recharge volume for the Cikapundung-Gandok watershed is 33,232,004 m³/year or 1.05 m³/s, with the lowest contribution from the Lava formation (Qyl) at 1,364,504 m³/year or 0.04 m³/s and the highest from the Old Volcanic Product (Qvu) at 14,072,243 m³/year or 0.45 m³/s. The tentative recharge coefficients for each rock formation are as follows: Colluvium (Qc) 30%; Unweathered Old Volcanic Product (Qvu) 20%; Sand Tuff (Qyd) 10%; Lava (Qyl) 25%; Pumiceous Tuff (Qyt) 20%; and Young Volcanic Product (Qyu) 20%. The groundwater recharge data obtained can be used to set groundwater extraction limits and to plan for groundwater management using a conservative approach to ensure long-term sustainability.Keywords: groundwater recharge, recharge coefficient, geological formation, groundwater exploitation, Cikapundung-Gandok Watershed

Investigation of Saltwater Intrusion into Freshwater Aquifers in Some Estuary Environment in Niger Delta

Investigation of Saltwater Intrusion into Freshwater Aquifers in Some Estuary Environment in Niger Delta

Long‐term monitoring of water table and saltwater intrusion dynamics through time‐lapse transient electromagnetic

AbstractUnderstanding hydrogeological processes often requires continuous measurements, which in many cases are not cost‐efficient. Time‐lapse geophysical studies are invaluable for investigating dynamic subsurface processes. They offer several advantages over traditional borehole‐based monitoring methods, such as being cost‐efficient and non‐intrusive. However, to be effective as an early warning tool, these studies must provide real‐time information on the processes. This is often not feasible with traditional geophysical methods, which typically do not offer real‐time monitoring. In this study, we present a windowed inversion approach for time‐lapse transient electromagnetic (TEM) monitoring. The advantages of this approach include: (i) immediate and continuous results as each time‐step dataset is acquired; (ii) no limitations on the size of the monitoring period or dataset; and (iii) the use of model information from previous inversion results for robust and continuous outcomes. The results from a synthetic study are followed by two field case studies, demonstrating the advantages of the windowed inversion compared to the inversion of the full dataset. We monitored the water table dynamics of a shallow unconfined aquifer over 8 months and the saltwater intrusion in a confined aquifer over 10 months using a monitoring TEM (mTEM) system while collecting nearly continuous daily measurements. With the windowed approach, the water table dynamics was recovered with an accuracy of 10 cm, and the changes in salinity were tracked with results comparable to those of an EC data logger.

Tectonic Control of Aseismic Creep and Potential for Induced Seismicity Along the West Valley Fault in Southeastern Metro Manila, Philippines

Vertical creep along 15 ground ruptures within a 15 km long and 1.5 km wide zone has been occurring along the southeastern part of Metro Manila. Though the unusually high rates of vertical slip point to excessive groundwater withdrawal as the trigger, the evidence presented herein indicates that these may not be simple irregular subsidence fissures. Tectonic control of creep along these traces is suggested by the following: the occurrence of some of these ground ruptures along pre-existing scarps that coincide with topographic and lithologic boundaries, the left-stepping en echelon pattern of surface rupturing, and the distribution of the creeping zone within the dilational gap of the dextral strike-slip West Valley Fault (WVF). Furthermore, interpretation of an exposure across one of the creeping faults indicates reactivation by creep of a pre-existing tectonic fault zone. The paleoseismic evidence also suggests that the pre-creep slips are coseismic and dominantly strike-slip. Recognizing the occurrence of coseismic slip preceding aseismic creep is a primary consideration in assessing the potential of the WVF’s creeping segment and its adjacent segments in generating earthquakes. Tighter groundwater extraction regulations may be necessary to avoid exacerbating the effects of vertical ground deformation and the occurrence of induced seismicity.

Water Volume and 3D Topographic Analysis of Hub Dam, Karachi, Using Remote Sensing and Global Bathymetry Data

Background: Karachi one of the largest and fastest-growing cities in the world, the city faces severe water scarcity and aggravated by climate change, excessive groundwater extraction in dense urban areas and inefficient water distribution systems. The Hub Dam, along with the Keenjhar Lake, is the source of water for Karachi's population as well as for the industrial and urban agricultural sectors. It is therefore important to have current information on the dam's storage capacity, its topographic features and the hydrological dynamics of its catchment area, which remains poorly understood to date. Objectives: This study's primary objectives are (1) to assess the hydrography of Hub Dam using global bathymetric and remote sensing data and (2) to create a detailed 3D model of the dam to facilitate analysis of its hydrological features. (3) Also generate data-driven insights to guide improvements in Karachi’s urban water management policies. Methods: The methodology integrates global bathymetric data with remote sensing and Google Earth Engine (GEE) for analysing Hub Dam’s hydrological and topographic characteristics. Data processing and visualization were conducted in Google Colab by python codes. This process enabling an efficient workflow for handling and analysing large datasets. Results: Hub Dam 3D model is developed. The approaches is enhancing visualization of the dam's water volume and terrain features to support detailed hydrological analysis. 3D volumetric analysis estimates with total water volume at approximately 79.954 · 106 m3. It was found that currently, the Hub Dam reservoir has enough water to fulfil Karachi needs for 503 days, a critical reserve for urban planning, resource management. Using a topographic analysis that includes surrounding slopes and watershed features, key elements affecting dam performance were identified. This result helps to adjust the filling of the dam with water. The Hub Dam's ability to store water was confirmed through a preliminary volume assessment. Conclusion: The study successfully achieved its objectives. The results obtained highlight the importance of adaptive well informed strategies for sustaining well managed water resources in response to environmental pressures. The current study further advance rational water management by integrating remote sensing and data-driven methodologies into this area of knowledge. That is, the effectiveness of Using Remote Sensing and Global Bathymetry Data has been repeatedly proven by other studies in different areas of knowledge. However, in the current study, this scientific approach has successfully demonstrated the efficient and rapid acquisition of accurate, up-to-date information on reservoir capacity and hydrological characteristics, which opens up new opportunities for efficient water management.

Cross Comparison of GALDIT Method Application in Three Costal Aquifers in Greece

Seawater intrusion into Greece’s coastal aquifers is a prevalent issue. The Greek coastline extends for 15,147 km. Once groundwater sources become contaminated, remediation methods are often challenging, costly, and protracted. This study focuses on three coastal aquifer systems in the Peloponnese region. Initially, the main ions and cations were determined for these aquifers. Hydrochemical analyses revealed elevated concentrations of Na+, Mg2+, Ca2+, SO42−, and Cl−, indicating a significant impact from seawater intrusion. The study evaluates the vulnerability of groundwater to this intrusion. Utilizing Geographical Information Systems (GIS) software (ArcGISPro), maps were created to illustrate each parameter of the GALDIT method. The acronym GALDIT encapsulates the main elements influencing seawater intrusion. Each parameter is analyzed as follows: Groundwater occurrence (including the following aquifer types: unconfined, confined, and leaky confined), Aquifer hydraulic conductivity, depth to groundwater Level above the sea, Distance from the shore (inland distance perpendicular from shoreline), Impact of existing status of sea water intrusion in the area, and Thickness of the aquifer. The final map that emerged from this study shows their vulnerability to seawater intrusion in Peloponnese. Notably, Larissos exhibits lower vulnerability in contrast to the seawater incursion in the other two groundwater systems.

Evaluating pile foundation design due to groundwater level lowering

In Viet Nam, ground subsidence has been occurring at an alarming rate, raising concerns for pile foundation design. This issue is primarily caused by excessive groundwater extraction for water supply, irrigation, aquaculture, and other uses. Thus, in this study, the evaluation of pile capacity due to groundwater level (GWL) lowering as a preliminary guideline for structures is proposed. This study analyzed different cases of GWL lowering from 0 m to 2 m, and pile size varied from 18 x 18 cm to 45 x 45 cm, to evaluate the allowable bearing capacities for single piles and pile groups. The results indicated that when lowering the GWL from 0 to 2 m, the allowed bearing capacity varied by 5.75–174.70 tons for single piles and 11.95–808.18 tons for pile groups. Besides, when the pile size increased, the bearing capacity increased in the range of 6.38–41.46 tons (size 18 x 18 cm) to 16.30–174.70 tons (size 45 x 45 cm) for a single pile and 11.95–191.81 tons (size 18 x 18 cm) to 33.49–808.18 tons (size 45 x 45 cm). The result of this study underscores the significance of predicting the bearing capacity of pile foundations due to the variation in groundwater level.

Prediction of the dynamic changes of water table based on the quantitative theory type I in the Piedmont Plain of the Taihang Mountains

Statistical analysis was conducted on groundwater table data in the Ji Yuan Basin from 2006 to 2018, revealing a continuous downward trend in the groundwater table with imminent depletion of shallow groundwater resources. To ensure the sustainable development of groundwater resources in the area, a quantitative model of groundwater table was successfully constructed using the principles of the Quantitative Theory Type I. This model included seven benchmark variables: rainfall, evaporation, exploitation, hydraulic conductivity, specific yield, lithology of the vadose zone, and land-use type. These factors are key contributors to the decline in groundwater levels in the study area. The model yielded an average residual value of 0.35 m and an adjusted R2 of 0.789, indicating that it can explain 78.9% of the benchmark variables with acceptable accuracy. Additionally, the model successfully simulated four types of groundwater dynamics, with the best results obtained for the rainfall infiltration-exploitation-evaporation type. This study’s findings suggest that the model can be utilized to predict the dynamic characteristics of the groundwater table and guide groundwater extraction activities.

The role of automated surface water distribution systems in energy-saving agriculture: A case study from central Iran’s Arid Plateau

Study regionThe NekooAbad Irrigation District in central Iran faces challenges due to inefficient surface water distribution. 82 million m3 of groundwater is extracted annually from 15,000 tube-wells, leading to decreased groundwater levels and increased energy consumption of 234 million kWh per year. Study focusThis study explores implementing automation in surface water distribution to reduce groundwater extraction and conserve energy. A hydraulic simulation model and a centralized Model Predictive Control approach were used to analyze the existing system and propose a recovery plan. The potential impact of automated surface water distribution on reducing groundwater extraction and energy conservation was evaluated through spatial assessment in GIS. New hydrological insights for the regionThe results demonstrate that the introduction of automation can significantly improve surface water distribution and, accordingly, groundwater overexploitation and, consequently, energy conservation, particularly during water scarcity. Energy conservation increased by 42.3 %, 54.8 %, 56.2 %, and 57.7 % under normal conditions, with water shortages of less than 10 %, 10–15 %, and 15–20 %, respectively. However, as the surface water shortages intensified, the energy conservation rates decreased to 57.7 %, 43.7 %, 25.4 %, and 18.9 % for normal conditions, water shortages of 15–20 %, 20–30 %, 30–40 %, and over 40 %, respectively. The automation introduction effectively provided reliable surface water resources, prompting farmers to shut down pumping stations or reduce working hours. Even in extreme scenarios, the project achieved up to 18.9 % energy savings.

Assessing the impacts of climate change on the vulnerability of coastal aquifers to the seawater intrusion

In most coastal areas, groundwater is affected by saltwater intrusion. Climate change effects, such as the sea-level rise and rainfall change are the climatic factors affecting the saltwater intrusion into groundwater. This study examines the vulnerability of the Abdan-Lamidan coastal aquifer to the intrusion of Persian Gulf saline waters under different hydrological conditions. First, the SIMCLIM model was used to calculate the regional sea-level rise of the Gulf under 24 future AOGCMs projections. The results showed that the increase in water level under the ensemble of AOGCM models and two RCP2.6 and RCP8.5 scenarios is 6.7 and 7.8 cm in 2050 compared to 2013. Then, the GALDIT vulnerability index was used to assess the vulnerability of the aquifer under the current condition and future scenarios. The results showed that parts of the aquifer that are currently at lower levels would be more vulnerable to sea-level rise in the future periods.

Storm surge, seawater flooding, and sea-level rise paradoxically drive fresh surface water expansion

Abstract Coastal storms and sea-level rise are expected to increase seawater flooding in low-elevation coastal zones. High sea levels and seawater flooding can drive groundwater table rise via ocean-aquifer connections. These dynamics are often overlooked but can cause groundwater flooding and salinization hazards, increasing freshwater security challenges for coastal communities and driving ecosystem transgressions. Field data and numerical modeling were used to evaluate how heavy rainfall, storm surge, and seawater flooding and infiltration during Hurricane Fiona (September 2022) and projected sea-level rise impact groundwater levels, inland surface waters, and saltwater intrusion on Sable Island National Park Reserve, Canada. During the passage of Hurricane Fiona, precipitation increased groundwater and pond levels before seawater flooded the beach. Seawater flooding and infiltration caused a sharp rise in beach groundwater levels, which in turn caused inland pond levels to rise without coincident direct inputs from precipitation or seawater. Model simulations reveal that seawater infiltration on beaches flooded the subsurface and drove the observed inland groundwater rise and freshwater pond expansion. Simulations of projected sea-level rise show that seawater flooding will only inundate a small area of land along the coast; however, inland groundwater rise and flooding, which is less well-studied, may inundate up to 30 times more land area. Further, groundwater flooding driven by rising sea levels decreases hydraulic gradients and increases saltwater intrusion via freshwater lens contraction. Findings demonstrate that seawater flooding from coastal storms and sea-level rise paradoxically cause concurrent fresh surface water expansion but freshwater lens contraction. This study provides new insights into the spatiotemporal dynamics of island freshwater resources and highlights that unseen and often overlooked groundwater-surface water exchanges are critical to consider when evaluating coastal flooding and groundwater salinization hazards and management strategies for low-elevation coastlines.

Watering the Seeds of the Rural Economy: Evidence from Groundwater Irrigation in India

ABSTRACT This study explores the impact of private investment in groundwater extraction for irrigation on the spatial and sectoral distribution of rural economic activity in India. Exploiting a kink in access to groundwater, generated from an absolute technological constraint on the operational capacity of irrigation pumps with depth of the water table, there is evidence of a significant improvement in agricultural production accompanied with modest consumption gains. Groundwater extraction causes a substantial increase in population density, but has no effect on the employment rate or labor reallocation between sectors of the economy. Furthermore, irrigated agriculture appears to provide additional employment opportunities for waged labor from surrounding non-irrigated villages.

A robust multi-model framework for groundwater level prediction: The BFSA-MVMD-GRU-RVM model

Groundwater level prediction is critical for environmental protection and agricultural planning. Accurate predictions help manage risks associated with excessive groundwater extraction and land subsidence. This study introduces a novel model combining multivariate variational mode decomposition (MVMD), gated recurrent unit (GRU), and relevance vector machine (RVM), along with the Boruta feature selection algorithm (BFSA), for precise groundwater level forecasting. The model operates in several stages. First, BFSA selects the most informative features as input data. Next, the MVMD method decomposes the time series of these features. The GRU model then extracts crucial information from these decompositions. Finally, the extracted data is fed into the RVM model to predict groundwater levels one month ahead in Iran's Bastam Plain. To assess the model's accuracy, multiple error indices were employed. The MVMD-GRU-RVM model outperformed other models, improving the testing Nash–Sutcliffe Efficiency and mean absolute error by 24–31 % and 6–61 %, respectively. Additionally, it enhanced R2 values of the MVMD-CNN, MVMD-RNN, MVMD-MLP, and MVMD-RBFNN models by 1.0–3.33 %. These results demonstrate that the MVMD-GRU-RVM model significantly improves groundwater level prediction accuracy. The key points of the paper are the successful effectiveness of MVMD in processing non-stationary time series and improving the predictive performance of the models, as well as the high ability of the GRU model in data feature extraction. The study also shows that the novel model can provide outputs with lower uncertainty.

Pemetaan Sebaran Salinitas di Desa Tanjung Pakis Kabupaten Karawang Menggunakan QGIS

The coastal area has a high likelihood of seawater intrusion, leading to the formation of brackish water. Brackish water is unsafe for consumption due to its high salt content, which exceeds 0.5 ppt. The purpose of this study is to identify the distribution of salinity by testing the well water of the residents in Tanjung Pakis Village, Karawang Regency. The sample determination method used is Systematic Grid Sampling. The grid used measures 1,000 x 250 m. In this study, 3 grids were used, each at different distances from the nearest coastline. Three samples were taken from each grid, resulting in a total of 9 samples. The parameter tested is salinity, which represents the salt content in the water. The method used to measure the salinity parameter is direct reading using a refractometer. The results of the study show that the highest salinity parameter value reached 120 ppt in Grid I, while the lowest salinity parameter value was 30 ppt in Grid II. The mapping results indicate high salinity values in Grid I, represented by a darker color. In Grid II, the salinity value decreases, indicated by a lighter color. An increase in salinity occurs in Grid III, shown by a darker color compared to Grid II.

Saltwater intrusion simulations in coastal karstic aquifers related to climate change scenarios

Coastal zones are crucial ecosystems supporting significant biodiversity and pertinent socio-economic activities. However, anthropogenic development contributes to socio-environmental complexities, particularly public water supply threats caused by climate change. This research presents a case study on the north-western coast of Yucatan, Mexico, which models potential saltwater intrusion in groundwater for multiple projections of sea level rise and recharge change due to climate change and its implications for the public water supply of the regional population and ecosystem. For this purpose, a previously calibrated and validated numerical model is employed, adapting its boundary conditions, keeping its calibrated hydrogeologic parameters, and considering the 2040 and 2100 climate change projections. Simulation results show that under these projections, significant saltwater intrusion may occur, reducing freshwater thickness due to increased salinity in groundwater and a loss of freshwater sources resulting from brackish-saline wedge intrusion. These scenarios are of particular concern as freshwater in this coastal region is the main source for public water supply and for freshwater input in coastal ecosystems. Moreover, this study underscores the susceptibility of karstic aquifers to salinization, especially in the face of rising sea levels, given their unique hydrogeological characteristics and substantial responsiveness to marine forcings. In spite of the uncertainties in global climate change predictions, this study enhances our understanding of the dynamics of these unique aquifers, and presents future saltwater intrusion projections that offer valuable technical insights to design and implement pertinent and resilient coastal aquifer management strategies.

Integrated geophysical and geospatial techniques for surface and groundwater modeling

An integrated approach using geophysical and geospatial techniques was employed to model the surface and subsurface water-bearing strata and assess aquifer vulnerability in the Sehnsa town, Kotli district, State of Azad Kashmir, Pakistan. The inadequate scientific studies in the hilly terrain with such complex geological conditions has led to the failure of the boreholes for groundwater extraction. For the evaluation of groundwater potential and subsurface lithology, 30 vertical electrical soundings (VES) stations utilizing the Schlumberger electrode configuration were completed, modeled and analyzed spatially. Numerous geoelectrical parameters like true resistivity, thickness of subsurface layers and Dar-Zarrouk parameters were evaluated. The subsurface lithology delineated comprised topsoil, clayey sand, sandstone, and boulder clays which closely resemble to the borehole lithologs available in the study area. The inversion model confirms the presence of patches of high-resistivity sandstone in the southwestern part of the study area with the maximum thickness of the aquifer up to 140 m. Most aquifers were classified as unconfined with Q–type resistivity curves. The protective overburden capacity of the aquifers is rated as poor at VES 1, 3–5, 8, 10–16, 18, 19, 22–25, 27 and 30 whereas the moderate category was found at VES 2, 9 and 20 and excellent at VES 7 and 28, respectively. Therefore, the VES stations with poor and moderate ratings of overburden protective capacity are vulnerable for surface contaminants. The aquifer recharge was associated with rainfall and partly from the Poonch River. The effective integration of geophysical and geospatial techniques in this study provides sufficient information about the regional water resources and gives a preliminary model that can facilitate efficient water resource management in the area. These approaches can be successfully applied to diverse geographical and hydrogeological sites due to their versatility and reliability.

Chloride in the Chalk aquifer of East Anglia, UK, Part 1: Distribution of chloride in brackish and saline groundwater

The Chalk aquifer of East Anglia is heavily exploited as a groundwater source. During exploration and exploitation, it has become clear that some of the groundwater in the Chalk is brackish and unsuitable for drinking (>250 mg/l chloride). Data comprising chemical analyses of pumped water samples and borehole depth samples (> 900 results in total), and downhole geophysical surveys have been used to assemble maps of the distribution of chloride areally and with depth. Brackish or saline water is probably present at depth in the Chalk, even where shallow fresh water is present, over much of the area where Crag Group marine sediments have been deposited. The depth below surface at which brackish water is encountered varies between 50 to >100 m, and the elevation of the transition varies from +16 mAOD to below 91 mAOD. From its chemistry it is deduced that most of the brackish water is of ancient marine origin, but that there has been localised intrusion of modern seawater in coastal areas, especially around Ipswich. Saline water most probably entered the aquifer during Crag Group times (late Pliocene-early Pleistocene) and its chemistry has been modified subsequently. The most saline old water that has been encountered has full marine salinity.