Special Issue "Coastal Aquifers: Seawater/Saltwater Intrusion"

A special issue of Water (ISSN 2073-4441). This special issue belongs to the section "Hydrogeology".

Deadline for manuscript submissions: 31 May 2022.

Special Issue Editors

Prof. Dr. Longcang Shu
E-Mail Website
Guest Editor
College of Hydrology and Water Resource, Hohai University, Nanjing, China
Interests: groundwater resources evaluation and management; groundwater reservoir; seawater intrusion
Prof. Dr. Fulin Li
E-Mail Website
Guest Editor
Water Resources Research Institute of Shandong Province, Jinan, China
Interests: water resource; water environment; seawater intrusion monitoring and simulaition; hydrogeology; spring protection

Special Issue Information

Dear Colleagues,

Social and economic development have had an impact on the earth’s systems, and external factors such as climate change, the rise of sea level, and the overexploitation of groundwater have destroyed the dynamic balance between the saltwater/seawater and fresh groundwater in coastal areas, further aggravating the degree of seawater intrusion. This has greatly restricted the social and economic development of coastal areas.

This Special Issue is dedicated to “Coastal Aquifers: Seawater/Saltwater Intrusion” and seeks to capture the most up-to-date research and practices. We therefore call for original papers from researchers, practitioners, regulators, and decision-makers presenting their findings on seawater/saltwater intrusion from different perspectives.

The topics of interest but are not limited to: seawater/saltwater intrusion; the development and utilization of freshwater lens; the response of the saltwater–freshwater interface to rising sea levels; induced saltwater upconing in coastal aquifers by pumping; modeling aquifer storage and recovery systems in coastal zones; and modeling new managed aquifer recharge schemes in coastal zones.

Full research articles, reviews, as well as shorter commentaries/communications from practitioners are welcome.

Prof. Dr. Longcang Shu
Prof. Dr. Fulin Li
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Water is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2000 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • saltwater intrusion
  • freshwater lens
  • saltwater–freshwater interface
  • saltwater upconing
  • modeling of coastal aquifers
  • management of coastal aquifers

Published Papers (4 papers)

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Research

Article
On the Understanding of the Hydrodynamics and the Causes of Saltwater Intrusion on Lagoon Tidal Springs
Water 2021, 13(23), 3431; https://doi.org/10.3390/w13233431 (registering DOI) - 03 Dec 2021
Viewed by 231
Abstract
Springs are common features on the Yucatán coast. They can discharge either under the sea (submarine) or inland in coastal lagoons and wetlands. Previous observations of a coastal lagoon located on the northern Yucatán Peninsula (La Carbonera) reported sea water intrusion on a [...] Read more.
Springs are common features on the Yucatán coast. They can discharge either under the sea (submarine) or inland in coastal lagoons and wetlands. Previous observations of a coastal lagoon located on the northern Yucatán Peninsula (La Carbonera) reported sea water intrusion on a spring that discharge on a coastal lagoon (lagoon tidal spring). The saltwater intrusion occurs when the tide is at its lower level, which is the opposite to what has been reported for submarine springs in the Yucatán Peninsula. In this study, the hydrodynamics of the spring is analyzed and the driving forces controlling the seawater intrusion are identified and discussed. Time series of water levels, salinity, and velocity measurements in the lagoon, the aquifer, and the spring are analyzed by means of tide component decomposition and cross-correlations analysis of the tide signals. Results show that the main driving forces causing the intrusion are the density differences and pressure head gradients, and the mechanisms influencing the driving forces driving those differences are the tides, the friction in the lagoon, and the confinement of the aquifer; other mechanisms are discussed to present a complete idea of the complexity of the interactions between the coastal aquifer, the coastal lagoons, and the sea. Full article
(This article belongs to the Special Issue Coastal Aquifers: Seawater/Saltwater Intrusion)
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Article
Laboratory and Numerical Study of Saltwater Upconing in Fractured Coastal Aquifers
Water 2021, 13(23), 3331; https://doi.org/10.3390/w13233331 - 24 Nov 2021
Viewed by 246
Abstract
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 [...] Read more.
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. Full article
(This article belongs to the Special Issue Coastal Aquifers: Seawater/Saltwater Intrusion)
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Article
Impact of Island Urbanization on Freshwater Lenses: A Case Study on a Small Coral Island
Water 2021, 13(22), 3272; https://doi.org/10.3390/w13223272 - 18 Nov 2021
Viewed by 343
Abstract
Freshwater resources on small coral islands mainly exist in the form of freshwater lenses. The freshwater lens is highly vulnerable to salinization due to natural recharge variations and urbanization construction. However, it is unclear how a freshwater lens evolves under the influence of [...] Read more.
Freshwater resources on small coral islands mainly exist in the form of freshwater lenses. The freshwater lens is highly vulnerable to salinization due to natural recharge variations and urbanization construction. However, it is unclear how a freshwater lens evolves under the influence of urbanization construction and which factors control its evolution. Based on the hydrogeological data of a small coral island in China, a corresponding 3D numerical model was established by the Visual MODFLOW software to investigate the formation and evolution of freshwater lenses under natural conditions. Thereby, the island reclamation scenario and impermeable surface scenario were set up and the changes in morphology and volume of the freshwater lens were analyzed. The results show the following: (1) After island reclamation and island building, the freshwater lens would reach a stable state after 25 years and the freshwater lens would also appear in the newly added part of the island with a thickness of 9.5 m, while the volume of the total freshwater lens would increase to 1.22 times that of the original island. (2) When the impermeable surface is built at different positions of the island, the reduction in the volume of the freshwater lens, in the order from large to small, is Scenario B (northeast side), Scenario A (southwest side) and Scenario C (central); with the increase in the impermeable surface area, the volume of the freshwater lens would gradually decrease and the volume of the freshwater lens would decrease by more than 50% with the impermeable surface exceeding 30% of the island area. The study has important implications for the conservation and rational development of subsurface freshwater resources on islands. Full article
(This article belongs to the Special Issue Coastal Aquifers: Seawater/Saltwater Intrusion)
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Article
Pumping Well Layout Scheme Design and Sensitivity Analysis of Total Critical Pumping Rates in Coral Island Based on Numerical Model
Water 2021, 13(22), 3215; https://doi.org/10.3390/w13223215 - 12 Nov 2021
Viewed by 389
Abstract
Groundwater on small coral islands exists in the form of freshwater lenses that serve as an important water resource for local inhabitants and ecosystems. These lenses are vulnerable to salinization due to groundwater abstraction and precipitation variation. Determination of the sustainable yield from [...] Read more.
Groundwater on small coral islands exists in the form of freshwater lenses that serve as an important water resource for local inhabitants and ecosystems. These lenses are vulnerable to salinization due to groundwater abstraction and precipitation variation. Determination of the sustainable yield from freshwater lenses is challenging because the uncertainties of recharge and hydrogeological characteristics make it difficult to predict the lens response to long-term pumping. In this study, nine pumping well layout schemes along a line are designed using the orthogonal experimental design method, and an optimal well layout scheme is determined by multi-index range analysis and comprehensive balance analysis method. The total critical pumping rates of the freshwater lens corresponding to different schemes are calculated by numerical simulation, and the sensitivity of the total critical pumping rates to hydrogeological parameters is analyzed. The results show that the calculation of the total critical pumping rates needs to be combined with the specific well layout scheme with consideration to the length of well screens, the number of wells and the distance between wells. The difference in total critical pumping rates between different schemes can be up to three times. The uncertainty of hydrogeological parameters has a great impact on the total critical pumping rates. Within the range of a 30% reduction in parameters, α and K are the key risk factors of pumping; within the range of a 30% increase in parameters, α, ne and K are the key risk factors; α-ne combined changes had the greatest impact. The management of freshwater lenses and the assessment of sustainable yield will continue to be important tasks for coral islands in the future, and this study can help with the sustainable exploitation of island freshwater lenses. Full article
(This article belongs to the Special Issue Coastal Aquifers: Seawater/Saltwater Intrusion)
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