Aquifer Salinization Research Articles

Hydrogeochemical assessment of aquifer salinization in north-eastern Morocco's Gueroaou coastal plain using statistical methods

The Guerouaou aquifer investigation spanning 280 km2 in Ain Zohra yields promising outcomes, instilling optimism for regional water quality. These analyses were applied to 45 sampling instances from 43 wells, enabling a comprehensive water quality assessment. Groundwater conductivity ranged from medium to high, peaking at 18360 ms/cm2. The conductivity reveals insights about the groundwater's mineralization. Key physiochemical parameters fell within desirable thresholds, bolstering the positive perspective. HCO3− levels spanned 82–420 mg/L, while chloride content ranged from 38 to 5316 mg/L, benefiting water quality. NO3− ions, vital for gauging pollution, ranged from 0 to 260 mg/L, indicating favorable results. Cation concentrations exhibited encouraging variations: Ca2+- 24 to 647 mg/L, Mg2+- 12 to 440 mg/L, Na+- 18 to 2722 mg/L, K+- 1.75 to 28.65 mg/L. These collectively favor water quality. Halite breakdown dominated mineralization, as evidenced by the prevalence of Na–Cl–Na–SO4 facies. Water resource management and local communities need effective management and mitigation strategies to prevent saltwater intrusion.

Groundwater for drinking and industrial purposes: A study of water stability and human health risk assessment from black sand mineral rich coastal region of Kerala, India

Tempero-spatial analysis of groundwater to disseminate the level of drinking water quality and industrial suitability to meet the developmental requirement of a region is a significant area of research. Accordingly, groundwater quality and geochemical interactions prevailed in a black sand mineral rich coastal village is systematically presented in appraisal of drinking and industrial uses for economic engineering purposes. The study area focused is Alappad village, Kollam, Kerala, India has numerous ecological features in a sustainable perspective. The region is unique with placer deposits where an alluvial soil aquifer–saline water–freshwater interaction occurs. This dynamics decides the pertinent hydro geochemistry, potable and designated uses of ground water in season wise. Coastal area is hereby presented based on water quality parameters predicted with the health risk assessment model with a view on human health and cancer risk due to ions (Pb, Ni, Cu, Ba, Fe, Al, Mn, Zn) in groundwater.. To ascertain industrial usage, ground water is evaluated by Langelier saturation index (LSI), Ryznar stability index (RSI), Aggressive index (AI), Larson-Skold index (LS) and Puckorius scaling index (PSI) and inferences are complemented. Chemical weathering and evaporation processes are the natural factors controlling hydrochemistry of this aquifer. This complex coastal system has Nemerow pollution index (NPI) of moderate pollution for total dissolved ions of Fe and lesser for Cu, and Cr present in groundwater. LSI indicates, water is scale forming but non corrosive (46% in PRM, 20% in MON and 47% in POM). Water quality index (WQI) in POM (ranged 28.7–79.9) was excellent for drinking, followed by PRM (23.6–218.2) and MON (33.4–202.7) seasons. This groundwater bears temporary hardness with the dominance of Ca–Mg–HCO3 water type. Health risk assessment of non-carcinogenic risk index of trace metals (Fe, Zn, Mn, and Pb) revealed, children are at ‘low risk’ and ‘medium’ risk with Ni and Cu. The carcinogenic risk index indicated 93% of samples were high Ni induced cancer risk for children, and 87% for adults due to long term ingestion (drinking water intake) pathway. Studies specific on placer mineral deposited coastal region of India are not sufficiently reported with a focus on the above perspectives. Growing need of rare earths for material, device and energy applications, placer mineral explorations can destabilise the coastal hydrosphere. Interrelations of mineral soil – water chemistry prevailed and health hazard predicted would kindle a set of sustainable deliberations. This study summarises the drinking and industrial use of coastal groundwater for future development and human well-being on the basis of quality criteria, corrosion proneness, water stability and health risk factors.

Hazards of sea level rise and dams built on the River Nile on water budget and salinity of the Nile Delta aquifer

Study regionThe Nile Delta region consists of flat, low-lying areas, where most areas are used for agriculture. It covers an area of 22,000 km2, which is 2.20% of the total area of Egypt. Study focusThis study evaluates the water budget and the salinity due to the Sea Level Rise (SLR) and the reduction in the river water flow caused by the Grand Ethiopian Renaissance Dam (GERD) using the numerical code SEAWAT. Three filling scenarios were considered for the GERD reservoir at elevations 600 m, 621 m, and 645 m above mean sea level (AMSL) for the storage volumes of 17 billion cubic meters (BCM) (scenarios #1), 37.30 BCM (scenarios #2), and 74 BCM (scenarios #3). The impact of these fillings scenarios was combined with SLR of 25 cm, and increasing the abstraction rates from the Nile Delta aquifer by 25%, 50%, and 100%, respectively. New hydrological insights for the regionThe study findings indicated that the SLR and the GERD reservoir filling with increasing pumping rates, especially during the filling periods, would influence the groundwater resources in the Nile Delta. The GERD reservoir filling could alter the freshwater, in which the aquifer salinity increased by 4.47%, 11.48%, and 29.99% for the three scenarios, respectively. The methodology and findings presented in this study might be useful for investing and comparing the impact of SLR and upstream dam projects on the downstream water budget and salinity at other coastal regions.

Assessment of Salinity in Fresh and Saline Aquifers in the Coastal Area of Jiangsu Province

Within the littoral alluvial expanse of the Yangtze River Delta, the phreatic zone encompassing the aquifer represents a prolific ecosystem, which has been subjected to an enduring epoch of marine sediment deposition, and is conspicuously susceptible to the escalating phenomenon of urbanization. The prodigious abstraction of the groundwater reserves has engendered a recent encroachment of seawater and leakage of connate saline water, culminating in the salinization of freshwater sources. For an incisive comprehension of the gradations of salinity (viz., fresh, brackish, and saline) and to execute evaluations of the groundwater’s quality, the spatial distributions of the total dissolved solids (TDS) were interpolated employing bifurcate power functions that establish a relationship between the Vertical Electrical Sounding (VES)-predicated transformation average resistivity and the assayed TDS from the systematically sampled boreholes corresponding to the aquifer stratum. The scrutiny of the groundwater’s physicochemical attributes is of paramount significance to efficaciously steer the exploitation and management of hydric resources within the area under investigation.

Evaluating groundwater quality using health risk assessment and irrigation indexes: Saveh Aquifer, Iran

Abstract The aim of the study was to assess water quality in the Saveh aquifer for drinking, public health, and agricultural uses. The heavy metal pollution index (HPI), hazard index (HI) using non-carcinogenic health risk assessment, sodium percentage, sodium adsorption ratio (SAR), irrigation water quality index (IWQI), and a Piper diagram were used. The HPI exceeded 3,300, much higher than the WHO critical value, which is 100. The aquifer is severely contaminated with heavy metals and unsuitable for drinking. The heavy metal concentrations also caused the water to have cumulative HI > 1 in 54 and 77% of sampling wells, respectively, for adults and children. For agriculture, both %NA and IWQI were stricter than SAR. Most of the aquifer was deemed suitable for irrigation using SAR, while %Na showed most parts unreliable, and IWQI represented almost all areas unsuitable for irrigation. The Piper diagram showed that the dominant water type was N–Cl, followed by Na–HCO3 and Ca–HCO3, indicating high aquifer salinity. Generally, the Saveh aquifer is saline and heavily polluted with heavy metals, so its use for drinking and/or irrigation carries many risks.

Uncertainty quantification in coastal aquifers using the multilevel Monte Carlo method

AbstractWe are solving a problem of salinisation of coastal aquifers. As a test case example, we consider the Henry saltwater intrusion problem. Since porosity, permeability and recharge are unknown or only known at a few points, we model them using random fields and random variables. The Henry problem describes a two‐phase flow and is non‐linear and time‐dependent. The solution to be found is the expectation of the salt mass fraction, which is uncertain and time‐dependent. To estimate this expectation, we use the well‐known multilevel Monte Carlo (MLMC) method. The MLMC method takes just a few samples on computationally expensive (fine) meshes and more samples on cheap (coarse) meshes. Then, by building a telescoping sum, the MLMC method estimates the expected value at a much lower computational cost than the classical Monte Carlo method. The deterministic solver used here is the well‐known parallel and scalable ug4 solver.

Mitigating seawater intrusion in coastal aquifers: Novel approach with treated wastewater injection and groundwater circulation

Seawater intrusion (SWI) is a natural phenomenon that negatively impacts the potability of groundwater and is expected to worsen with rising sea levels due to climate change. Artificial recharge of freshwater is a commonly-used remediation method to mitigate SWI and improve freshwater supply security in affected coastal aquifers. However, limited freshwater availability can limit the effectiveness of this approach. This study proposes a novel mitigation measure, called Inj-GCW, which combines the injection of reclaimed water with the use of groundwater circulation wells (GCW) to enhance the effectiveness of artificial recharge in controlling SWI. GCW is a dual-screened well with isolated screens that extract and inject groundwater into the aquifer. The performance of the proposed measure was quantitatively evaluated using an illustrative simplified unconfined coastal aquifer. Based on the findings, the design parameters were estimated for a field-scale case study of the Nile Delta aquifer (NDA), a large Mediterranean coastal aquifer in Egypt. The study adopts a future scenario that considers Sea-level rise due to climate change and projected population growth by 2100. Results demonstrate that introducing of GCWs into the saltwater wedge, along with injection, effectively retreated the saltwater wedge, due to enhanced velocity, seaward fluxes, and dilution of contamination. Inj-GCW measure led to an 8.9% reduction in SWI and a 5.2% decrease in aquifer salinity compared to the expected intrusion in 2100. Furthermore, the Inj-GCW measure resulted in a 2.2% higher repulsion rate and 0.3% reduction in total salt mass compared to injection alone. The Inj-GCW measure presents a promising solution to SWI challenges in the NDA and other coastal aquifers facing similar issues. The formation of a brackish water bubble at the injection well screen of the GCW and the generated vertical groundwater circulation cells acted as a hydraulic barrier and contributed to the proposed method effectiveness.

A scenario-based food security analysis and halophyte crop suitability assessment in dying lake environments impacted by climate change

Climate change has significantly impacted food shortages over the past decades, and predicted projections have also indicated potentially intensive consequences for species diversity and natural environments in the coming decades. Climate change in the form of drought has resulted in environmental impacts on global dying lakes (GDLs), such as water scarcity, land degradation and food shortage. Thus, new comprehensive environmental impact assessment methods are urgently needed for GDLs to inform decision-making and minimise the negative impacts on the environment and human life and wellbeing. As state of art and progressive research, the main objective of this research is to develop an approach using a comprehensive and transferable geographic information science scenario-based suitability assessment to analyse the capability of halophyte plants as alternatives for crop modification in GDL areas. The approach was developed and examined for Salicornia suitability mapping in the Lake Urmia Basin as one of the most critical GDL cases. To obtain the ecological requirement information, we performed a scenario-based cultivation experiment on Salicornia under different salinity conditions. Accordingly, we employed relevant ecological requirements and environmental indictors for the Salicornia plant (e.g. soil characteristics and climate) to identify suitable areas for cultivating this plant under scenario-based spatial modelling and performed an uncertainty analysis. The results were achieved and validated in a field operation and laboratory analysis. According to the results, the Salicornia plant can be efficiently considered an alternative crop in farmlands around Lake Urmia that are impacted by intensive soil, aquifer salinisation and food production issues. Results pointed out that about 4.6% of the area (2372 km2) is highly suitable for the cultivation of Salicornia. As state of the art, our approach was developed in a semi-automated context but can also be customised and applied to similar case studies in GDL environments. We expect that the information and insights gained from such assessments will support stakeholders, decision makers and authorities in the development of effective policies and plans for mitigating the impacts of climate change on the fragile ecosystems of GDLs.

Managing coastal aquifer salinity under sea level rise using rice cultivation recharge for sustainable land cover

Study regionThe coastal aquifer of Nile Delta, Egypt is used to develop the current study. Study focusExcess water from rice irrigation is a source of incidental recharge to mitigate seawater intrusion. This paper numerically explores the optimal location of rice cultivations by subdividing the delta domain into three distinct recharging regions (north, central and south). Additionally, SEAWAT code was simulated under a combination of rice cultivation relocation and sea level rise (SLR). New hydrological insights for the regionThe study findings revealed significant variations in salt volume reduction depending on the location of rice cultivation in the delta. Placing rice cultivation in the northern region resulted in the highest reduction of salt volume (19 %). In contrast, locating the recharge in the central region yielded a salt volume reduction of 0.50 %, while rice cultivation in the southern region produced a 15 % increase. Considering the projected SLR of 61 cm by 2100, there was an overall salt volume increment of 3 %. However, when accounting for both SLR and rice cultivation recharge in the northern region, a substantial salt volume reduction of 17 % was observed. The results demonstrated that incidental recharge by rice cultivation in coastal aquifers is an effective method for enhancing saltwater intrusion control. Moreover, this study improves our understanding of hydrological processes and expected responses in the delta under future climate scenarios.

Groundwater Quality Variations in Multiple Aquifers: A Comprehensive Evaluation for Public Health and Agricultural Use

Understanding hydrological and hydrochemical processes is crucial for the effective management and protection of groundwater resources. This study conducted a comprehensive investigation into hydrochemical processes and variations in groundwater quality across five distinct aquifers in Phra Nakhon Si Ayutthaya, Thailand: Bangkok (BKK), Phra Pradaeng (PPD), Nakhon Luang (NKL), Nonthaburi (NTB), and Sam Khok (SK). Utilizing various diagrams, the findings revealed that high levels of sodium and salinity in shallow aquifers (BKK and PPD) were found which can impede soil permeability and have potential consequences on crop yields. The presence of four distinct types of groundwater—Na-Cl, Na-HCO3, Ca-Cl, and Ca-HCO3—suggests the influence of rock weathering, mineral dissolution, and ion exchange reactions with the surrounding geological formations, controlling the chemistry in the groundwater basin. The research also highlights concerns regarding groundwater quality, particularly elevated concentrations of heavy metals (e.g., Zn, Hg, Pd, Fe, and Mn) exceeding safe drinking water guidelines established by the World Health Organization (WHO) in certain samples. The evaluation of water suitability for consumption and irrigation using the Water Quality Index (WQI) and Wilcox diagram reveals a predominance of “poor” or “unsuitable” categorizations. Untreated sewage discharge and fertilizer usage were identified as the primary anthropogenic activities affecting hydrochemical processes in groundwater. These findings emphasize the need for continuous monitoring, appropriate management, and remediation efforts to mitigate potential hazards.

Assessment of inland salinity in a hard rock aquifer of south India

Assessment of inland salinity in a hard rock aquifer of south India

Assessment of Pleistocene Aquifer Vulnerability to Saline Intrusion in the Coastal Region of Ba Ria-Vung Tau Province Using GIS and Entropy-GALDIT

Sea-level rise, in the context of climate change, increases the likelihood of seawater intruding into coastal aquifers. This study assesses the vulnerability of the Pleistocene aquifer in the coastal area of Ba Ria-Vung Tau province, Vietnam. Data for calculation and analysis were collected from 99 boreholes in the study area. Using the vulnerability assessment index (GALDIT) with expanded weights, the vulnerability of the aquifer to the influence of coastlines was evaluated and visualized in a GIS environment. The set of Entropy weights used clearly shows the significance of the component parameters and indicates the characteristics of the risk partitioning of aquifer salinization. The Entropy-GALDIT results divided the Pleistocene aquifer in the coastal area of Ba Ria-Vung Tau province into three levels of vulnerability: high vulnerability zones (3.88% of the area), medium vulnerability zones (55.47%), and low vulnerability zones (40.65%). According to the GALDIT susceptibility zoning map, the western area of Phu My town (along the Thi Vai River), the southwest region of Vung Tau City, and the southeast region of Dat Do District are highly sensitive and not recommended for any purpose. This result provides useful insights into the vulnerability of aquifers in the coastal area of Ba Ria-Vung Tau province, with respect to factors such as the height of the groundwater level above sea level, the distance from the shore to the wells, and the impact of existing seawater intrusion. Accordingly, it is necessary to establish monitoring systems to warn of saltwater intrusion and to develop integrated resource management strategies to ensure the sustainability of groundwater resources in the area.

Evolutionary history of the groundwater system in the Pearl River Delta (China) during the Holocene

Abstract Coastal groundwater reservoirs are sensitive to the complicated evolution of marine transgressions and regressions in river delta regions. We integrated hydrogeological investigation and hydrogeochemical data with numerical modeling to assess the evolution of the groundwater system in the Pearl River Delta’s aquifer system (in southeastern China). We studied the effects of flow dynamics and redox conditions on the biogeochemical processes of nutrients in the regional groundwater flow systems in response to the transient states related to variable paleoprecipitation and seawater salinity decline from the late Pleistocene to the Holocene. The results from paleo-hydrogeological reconstruction of the aquifer-aquitard system showed that the saline groundwater formed by paleo-seawater intrusion was still present in the old marine aquitard and affected groundwater salinity and chemicals in the adjacent aquifers, while most of the groundwater in the shallow young marine aquitard has been freshened by infiltrated old/fresh rainwater. Consequently, total ammonium and carbon stored in the Pearl River Delta were estimated to be (1.91 ± 1.13) × 107 mol m–1 and (5.74 ± 4.05) × 107 mol m–1, respectively, and the ammonium and bicarbonate fluxes derived from groundwater discharge to the sea were calculated as (90.6 ± 55.9) mol m–1 yr–1 and (301.02 ± 196.23) mol m–1 yr–1, respectively. If the buried ammonium in the delta is released to the sea, it would be equivalent to nearly 205 ± 123 yr of Pearl River fluvial loading. These findings suggest that the chemicals trapped in the deltaic aquifer system during the Holocene could contribute to future ocean eutrophication and acidification.

Impacts of Subsurface Dam Construction on Downstream Groundwater Levels and Salinity in Coastal Aquifers.

Subsurface dam is a promising engineering technology for groundwater resources development. However, the possible impacts of these dams on the groundwater environment have been a major concern. Here, we used a three-dimensional (3D), variable-density, unsaturated-saturated groundwater flow model to explore how a groundwater-storage-type subsurface dam, built in the freshwater domain of an unconfined coastal aquifer, affected groundwater levels and salinity in the downstream area. Model results suggested that, after subsurface dam construction, groundwater levels in the downstream area showed intensified fluctuations in terms of phase advances, greater amplitudes, and higher frequencies following heavy rainfall events. Numerical simulations with variable subsurface dam scenarios indicated that the groundwater level fluctuations were further intensified with a higher crest elevation or a shorter distance from the coast. Moreover, during the recharging period of the subsurface reservoir, sea water in the downstream area intruded landward from its initial location, which can at least temporarily threaten water quality near the coast. A higher dam crest elevation prolonged the duration of sea water intrusion, while a dam positioned closer to the coast induced sea water intrusion with a greater horizontal extent. General implications are discussed with respect to improving assessment methodologies and engineering designs of subsurface dams.

Origin and Enrichment Mechanisms of Salinity and Fluoride in Sedimentary Aquifers of Datong Basin, Northern China.

The exposure of inhabitants to high fluoride and saline groundwater is the main health issue in Datong Basin, Northern China. This study aims to elucidate the spatial distribution and the mechanisms of high fluoride and salinity occurrence in the shallow sedimentary aquifers of the Datong Basin. Groundwater salinity and fluoride content, and their association with measured hydrochemical parameters, were conducted using multivariate statistical analyses. The analytical results revealed that the concentrations of fluoride and total dissolved solids (TDS) show dramatic variations within the study area. Around 41.4% of groundwater samples contained high-level fluoride concentration (F- > 1.5 mg/L), whereas 32.8% contained elevated-level TDS (TDS > 1000 mg/L). Both fluoride and TDS concentrations had elevated trends towards the central part of the basin. Shallow groundwater was seriously affected by evaporation and evapotranspiration, which can be the critical factors responsible for rather high TDS and F- concentrations in shallow aquifers. Water-rock reactions including silicate hydrolysis, dissolution-precipitation of carbonates and evaporates, adsorption, and ion exchange processes, as well as evapotranspiration, are the main governing factors for salinity and fluoride enrichment in groundwater. Solubility control of F-bearing and carbonate minerals is the dominant mechanism affecting F- levels. Prevailing conditions of alkaline pH, moderate TDS and Na+, high HCO3-, and lower Ca2+ content facilitate the enrichment of fluoride in the study area. Excessive evapotranspiration can be also the most influencing factor responsible for high fluoride and TDS content, due to the extended residence time of groundwater and the arid climate of the central part of the Datong Basin.

Aquifer salinization: A groundwater appraisal of northeast coast of Odisha using water quality index (WQI) and geospatial interpretation

Aquifer salinization: A groundwater appraisal of northeast coast of Odisha using water quality index (WQI) and geospatial interpretation

Delineation of Salinization and Recharge Sources Affecting Groundwater Quality Using Chemical and Isotopic Indices in the Northwest Coast, Egypt

Salinization of coastal aquifers is a serious issue affected by climate change and enhanced by overexploitation of groundwater resources. This research aims to explore the hydrogeochemical processes that cause salinization of groundwater in coastal aquifers, such as the area located between Barrani and Baqbaq, on the northwestern coast of Egypt. Various techniques were applied, including Gibbs plots and hydrochemical facies diagrams (HFE-D), ion ratios and stable isotope bivariate plots, statistical analyses, a groundwater quality index for seawater intrusion (GQISWI), and a seawater mixing index (SMI). Based on the total dissolved solids (TDS), groundwater can be classified into four groups: slightly saline (9%), moderately saline (45%), highly saline (43%), and salty water (3%). The geochemical properties were further catergorized on the basis of other parameters and ion ratios, such as Caexcess, Nadeficit, Na/Cl, Cl/HCO3, and Br/Cl, which suggest the influence of cation exchange, seawater, and marine sediment dissolution. Additionally, stable isotopes indicated two groups. One of these has relatively high salinity and low isotopic content and is affected by the leaching and dissolution of marine deposits. The other group is enriched in δ18O and δD content, with much higher salinity due to mixing with seawater and evaporation. The GQISWI categorizes groundwater as saline and mixed (55 and 41%, respectively), followed by saltwater (4%), whereas the SMI calculations indicate that about 10% of the groundwater samples are impacted by seawater. Finally, the areal distribution of GQISWI and SMI identified some patches along the coastline as well as other inland places located about 12.5 km away from the sea that have undergone saltwater intrusion. In conclusion, overexploitation of groundwater should be avoided because the amount of annual rainfall is very limited.

Effects of Future Increases in Tidal Flooding on Salinity and Groundwater Dynamics in Coastal Aquifers

AbstractFuture increases in the frequency of tidal flooding due to sea level rise (SLR) are likely to affect pore water salinities in coastal aquifers. In this study, we investigate the impact of increased tidal flooding frequency on salinity and flow dynamics in coastal aquifers using numerical variable‐density variably‐saturated groundwater flow and salt transport models. Short (sub‐daily) and long (decadal) period tides are combined with SLR projections to drive continuous 80‐year models of flow and salt transport. Results show that encroaching intertidal zones lead to both periodic and long‐term vertical salinization of the upper aquifer. Salinization of the upper aquifer due to tidal flooding forces the lower interface seaward, even under SLR. System dynamics are controlled by the interplay between SLR and long period tidal forcing associated with perigean spring tides and the 18.6‐year lunar nodal cycle. Periodic tidal flooding substantially enhances intertidal saltwater‐freshwater mixing, resulting in a 6‐ to 10‐fold expansion of the intertidal saltwater‐freshwater mixing area across SLR scenarios. The onset of the expansion coincides with extreme high water levels resulting from lunar nodal cycling of tidal constituent amplitudes. The findings are the first to demonstrate the combined effects of gradual SLR and short and long period tides on aquifer salinity distributions, and reveal competing influences of SLR on saltwater intrusion. The results are likely to have important implications for coastal ocean chemical fluxes and groundwater resources as tidal flooding intensifies worldwide.

Challenges and approaches for management of seawater intrusion in coastal aquifers

Coastal aquifers provide water for over one billion people worldwide; however, they face seawater intrusion due to overpumping. The current and future challenges of coastal aquifer management involve issues such as climate change and the control of abstraction and recharge. Different management approaches are being used globally to prevent aquifer salinization. This essay presents the challenges and possible solutions while also discussing the different approaches and their needs for improvement.

Surface Water-Groundwater Connections as Pathways for Inland Salinization of Coastal Aquifers.

Coastal agricultural zones are experiencing salinization due to accelerating rates of sea-level rise, causing reduction in crop yields and abandonment of farmland. Understanding mechanisms and drivers of this seawater intrusion (SWI) is key to mitigating its effects and predicting future vulnerability of groundwater resources to salinization. We implemented a monitoring network of pressure and specific conductivity (SC) sensors in wells and surface waters to target marsh-adjacent agricultural areas in greater Dover, Delaware. Recorded water levels and SC over a period of three years show that the mechanisms and timescales of SWI are controlled by local hydrology, geomorphology, and geology. Monitored wells did not indicate widespread salinization of deep groundwater in the surficial aquifer. However, monitored surface water bodies and shallow (<4 m deep) wells did show SC fluctuations due to tides and storm events, in one case leading to salinization of deeper (18 m deep) groundwater. Seasonal peaks in SC occurred during late summer months. Seasonal and interannual variation of SC was also influenced by relative sea level. The data collected in this study data highlight the mechanisms by which surface water-groundwater connections lead to salinization of aquifers inland, before SWI is detected in deeper groundwater nearer the coastline. Sharing of our data with stakeholders has led to the implementation of SWI mitigation efforts, illustrating the importance of strategic monitoring and stakeholder engagement to support coastal resilience.