Management of Seawater Intrusion in Coastal Aquifers: A Review

Hussain, Mohammed S.; Abd-Elhamid, Hany F.; Javadi, Akbar A.; Sherif, Mohsen

doi:10.3390/w11122467

Cited by 126 publications

(53 citation statements)

References 95 publications

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“…Seawater intrusion occurs worldwide (Robinson et al, 2018;Werner et al, 2013). Various strategies (e.g., groundwater extraction reduction, artificial recharge, and/or engineering measures such as subsurface barriers) are used to mitigate seawater intrusion in coastal areas (Hussain et al, 2019;Jin et al, 2019). Among them, artificial recharge is practical and cost effective and is thus commonly adopted (Eslamian, 2014).…”

Section: Discussionmentioning

confidence: 99%

Thermal Effects on Flow and Salinity Distributions in Coastal Confined Aquifers

Xin

Nguyen

et al. 2020

Water Resources Research

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Coastal aquifers provide an important hydrologic connection between terrestrial freshwater and oceanic seawater. Understanding the water flow and salinity distributions in those aquifers is essential to manage seawater intrusion and regional groundwater resources. For the last 50 yr, these processes have been extensively examined; however, previous studies typically assumed isothermal conditions and overlooked groundwater-seawater temperature contrasts, as commonly found along the global coastline. Here, we validated a solute and heat transport model against laboratory experiments and then revisited the classical Henry problem for coastal confined aquifers. We found that as the seawater temperature increases or freshwater temperature decreases, the freshwater-seawater interface retreats seaward and thus the freshwater storage increases. This occurs as a result of temperature-induced changes to the fluid density and aquifer hydraulic conductivity. Furthermore, double diffusion of salt and heat can induce two circulation cells in opposing directions in the saltwater wedge once the seawater temperature exceeds that of groundwater by a certain extent. Consequently, the circulating seawater flux and associated travel time change dramatically compared with isotheral conditions. Overall, the effect of thermal forcing can be significant, as demonstrated by a sensitivity analysis considering a large range of groundwaterseawater temperature contrasts. These results highlight the impact of changing thermal regimes on the flow and salinity distributions in coastal confined aquifers and provide guidance for better assessment of water resources in coastal zones. Plain Language Summary Coastal zones are often densely populated with associated significant economic activity. Groundwater in coastal aquifers provides an essential freshwater resource for domestic and industrial use as well as food production. Intensive human activities and climate change cause water regime shifts and thus threaten water security in coastal areas. Coastal water resource assessments often overlook groundwater-seawater temperature contrasts, even though such contrasts are globally ubiquitous. Here, we show those assessments could be improved with thermal effects considered as temperature contrasts can markedly influence salinity distributions and water circulations in coastal aquifers. The results provide guidance for better assessment of water resources in coastal zones. Water temperature affects oceanland exchange and various biogeochemical processes, which should be considered in future studies including climate change evaluations.

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Section: Discussionmentioning

confidence: 99%

Thermal Effects on Flow and Salinity Distributions in Coastal Confined Aquifers

Xin

Nguyen

et al. 2020

Water Resources Research

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“…It is common for coastal aquifers around the world to be affected by seawater intrusion. As a result, seawater intrusion has drawn extensive attention from the international community, and relevant countries have been actively engaged in the research and treatment of seawater intrusion [16,17]. Internationally, the study of seawater intrusion began in the late 19th century: the establishment of Ghyben-Herzberg's hydraulic equilibrium theory at the interface of brackish and freshwater is a sign that seawater intrusion enters the stage of quantitative analysis [18].…”

Section: Introductionmentioning

confidence: 99%

Hydrochemical Characteristics and Irrigation Suitability Evaluation of Groundwater with Different Degrees of Seawater Intrusion

Wang

Liu

et al. 2020

Water

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Groundwater in coastal aquifers is often affected by seawater intrusion, resulting in water quality deterioration. Using groundwater influenced by seawater intrusion for irrigation can lead to crop failure, erosion of machinery and pipes, and adverse effects on farming. In this study, the results of water testing, methods of statistical analysis, ion ratios, a Piper diagram, and a variety of groundwater irrigation suitability models were used to analyze the chemical composition of groundwater and the influence of seawater intrusion. The result shows that the content of Na+, K+, Ca2+, Mg2+, Cl−, and SO42− in groundwater would increase due to seawater intrusion, and the increasing trend was consistent with the freshwater–seawater mixing line. With the deepening of seawater intrusion, the hydrochemical type gradually changes from Ca-HCO3·Cl to Na·Mg-Cl·SO4 and then to Na-Cl type, and the source of hydrochemical composition changes from “Rock Weathering Dominance” to “Evaporation Dominance”. When the Cl− concentration is greater than 7.1 meq/L, groundwater will corrode pipelines and instruments; when greater than 28.2 meq/L, excessively high salinity of groundwater will have adverse effects on planting; and when greater than 14.1 meq/L, the groundwater hardness is too high, which may make the groundwater unsuitable for cultivation.

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“…One of the potential management scenarios for reducing SWI and recovering groundwater resources is to decrease the abstraction rate in order to increase the groundwater table and decrease the landward hydraulic gradient, as one of the suggested scenarios in literature for managing SWI (Hussain et al 2019). A 30% reduction in the total abstraction rate would lead to about 50, 250 and 1,850 m backward movement (retreat) of saline water in the top aquifer along the A-A, B-B and C-C cross-sections, respectively.…”

Section: Resultsmentioning

confidence: 99%

“…The lower aquifer depicts a 25, 315 and 170 m retreat along the A-A, B-B and C-C cross-sections, respectively; therefore, the top aquifer would be influenced more by a reduction in abstraction. Another possible scenario to control SWI would involve relocating the coastal wells in the vicinity of the shorelines further inland (Hussain et al 2019) in the regions of Linyuan (E31), Xinyuan (T17), Donggang (T03), Linbian (T19), Jiadong (T21), and Fangliao (T16). The right side of the plain along the A-A cross-section shows a very low response for a 1-km inland relocation of wells with less than 5-m backward movement of seawater at all depths of the aquifer.…”

Section: Resultsmentioning

confidence: 99%

Modelling seawater intrusion in the Pingtung coastal aquifer in Taiwan, under the influence of sea-level rise and changing abstraction regime

Dibaj

Akrami

et al. 2020

Hydrogeol J

Self Cite

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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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Management of Seawater Intrusion in Coastal Aquifers: A Review

Cited by 126 publications

References 95 publications

Thermal Effects on Flow and Salinity Distributions in Coastal Confined Aquifers

Thermal Effects on Flow and Salinity Distributions in Coastal Confined Aquifers

Hydrochemical Characteristics and Irrigation Suitability Evaluation of Groundwater with Different Degrees of Seawater Intrusion

Modelling seawater intrusion in the Pingtung coastal aquifer in Taiwan, under the influence of sea-level rise and changing abstraction regime

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