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1.
Seawater intrusion is one of the most serious environmental problems in many coastal regions all over the world. Mixing a small quantity of seawater with groundwater makes it unsuitable for use and can result in abandonment of aquifers. Therefore, seawater intrusion should be prevented or at least controlled to protect groundwater resources. This paper presents development and application of a simulation‐optimization model to control seawater intrusion in coastal aquifers using different management scenarios; abstraction of brackish water, recharge of freshwater, and combination of abstraction and recharge. The model is based on the integration of a genetic algorithm optimisation technique and a coupled transient density‐dependent finite element model. The objectives of the management scenarios include determination of the optimal depth, location and abstraction/recharge rates for the wells to minimize the total costs for construction and operation as well as salt concentrations in the aquifer. The developed model is applied to analyze the control of seawater intrusion in a hypothetical confined coastal aquifer. The efficiencies of the three management scenarios are examined and compared. The results show that combination of abstraction and recharge wells is significantly better than using abstraction wells or recharge wells alone as it gives the least cost and least salt concentration in the aquifer. The results from this study would be useful in designing the system of abstraction/recharge wells to control seawater intrusion in coastal aquifers and can be applied in areas where there is a risk of seawater intrusion. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
2.
The Middle East and North Africa (MENA) region suffers from low precipitation and high evaporation. Coastal areas of the MENA region are usually densely populated; hence, the coastal aquifers are easily over-exploited beyond their safe yield, and seawater intrusion and aquifer salinization have been caused by the groundwater-level declines. Four studies in MENA coastal aquifers, on seawater intrusion modeling and aquifer recharge and salinization using isotopes, have been brought together in a topical collection and are discussed in this essay. A brief overview is given of managed aquifer recharge as an effective method to combat groundwater-level decline, seawater intrusion and aquifer salinization in MENA counties. 相似文献
3.
Review of coastal-area aquifers in Africa 总被引：3，自引：1，他引：2
The coastal aquifer systems of Africa are comprised of various geological formations. These aquifer systems consist of either folded, continental or alluvial deposits. Groundwater resource availability along the coastal areas of Africa is briefly reported and the current state of seawater intrusion has been summarized. A select number of notable examples are given to highlight the effect of saline intrusion on coastal development of cities and regional aquifers. The role of conflict resolution is briefly discussed, as well as management approaches, which include monitoring of contamination and governmental accountability. Regional cooperation is presented as a method of ensuring a sustainable water resource in an area, as well as strengthening social and political alliances. 相似文献
4.
GIS-based GALDIT method for vulnerability assessment to seawater intrusion of the Quaternary coastal Collo aquifer (NE-Algeria) 总被引：1，自引：0，他引：1
Boulabeiz Mahrez Stefan Klebingat Belgacem Houha Bousnoubra Houria 《Arabian Journal of Geosciences》2018,11(4):71
The overexploitation of groundwater in coastal aquifers is often accompanied by seawater intrusion, intensified by climate change and sea level rise. Heading long-term water quality safety and thus the determination of vulnerable zones to seawater intrusion becomes a significant hydrogeological task for many coastal areas. Due to this background, the present study focussed the established methodology of the GIS-based GALDIT model to assess the aquifer vulnerability to seawater intrusion for the Algerian example of the Quaternary coastal Collo aquifer. According to the result analysis overall, more than half of the total surface of the northern study area can be classified as highly vulnerable. Besides the coastline, the areas nearby the local wadis of Guebli and Cherka occur to be the most vulnerable in the region. In view of further map removal performance as well as single-parameter sensitivity analyses from a coupled perspective respectively the GALDIT parameters, distance from the shore (D) and aquifer hydraulic conductivity (A) have been found to be of key significance regarding the model results (mean effective weightings ~?18–19%). Overall, the study results provide a good approximation basis for future management decisions of the Collo aquifer region, including various perspectives such as identification of suitable settings for prospective groundwater pumping wells. 相似文献
5.
为实现滨海含水层地下水开采-回灌方案优化、控制海水入侵面积和降低海水入侵损失等多重管理目标,建立了海水入侵条件下地下水多目标模拟优化管理模型SWT-NPTSGA。模拟模型采用基于变密度流的数值模拟程序SEAWAT来模拟海水入侵过程。优化模型采用小生境Pareto禁忌遗传混合算法NPTSGA来求解,该算法在保证多目标权衡解的收敛性和计算效率的前提下,能维护整个进化群体的全局多样性。将SWT-NPTSGA程序应用于一个理想滨海含水层地下水开采方案和人工回灌控制海水入侵的优化设计中,结果表明该管理模型能够同时处理最大化总抽水流量、最小化人工回灌总量和最小化海水入侵范围等3个目标函数之间的权衡关系。通过采用人工回灌海水入侵区的减灾策略,既能增加滨海地区的供水量,又可减少海水入侵的范围,由此进一步验证了模型的有效性和可靠性。 相似文献
6.
Greece is dependent on groundwater resources for its water supply. The main aquifers are within carbonate rocks (karstic aquifers)
and coarse grained Neogene and Quaternary deposits (porous aquifers). The use of groundwater resources has become particularly
intensive in coastal areas during the last decades with the intense urbanization, tourist development and irrigated land expansion.
Sources of groundwater pollution are the seawater intrusion due to over-exploitation of coastal aquifers, the fertilizers
from agricultural activities and the disposal of untreated wastewater in torrents or in old pumping wells. In the last decades
the total abstractions from coastal aquifers exceed the natural recharge; so the aquifer systems are not used safely. Over-exploitation
causes a negative water balance, triggering seawater intrusion. Seawater intrusion phenomena are recorded in coastal aquifer
systems. Nitrate pollution is the second major source of groundwater degradation in many areas in Greece. The high levels
of nitrate are probably the result of over-fertilization and the lack of sewage systems in some urban areas. 相似文献
7.
A shallow unconfined low-lying coastal aquifer in southern Finland surrounded by the Baltic Sea is vulnerable to changes in groundwater recharge, sea-level rise and human activities. Assessment of the intrinsic vulnerability of groundwater under climate scenarios was performed for the aquifer area by utilising the results of a published study on the impacts of climate change on groundwater recharge and sea-level rise on groundwater–seawater interaction. Three intrinsic vulnerability mapping methods, the aquifer vulnerability index (AVI), a modified SINTACS and GALDIT, were applied and compared. According to the results, the degree of groundwater vulnerability is greatly impacted by seasonal variations in groundwater recharge during the year, and also varies depending on the climate-change variability in the long term. The groundwater is potentially highly vulnerable to contamination from sources on the ground surface during high groundwater recharge rates after snowmelt, while a high vulnerability to seawater intrusion could exist when there is a low groundwater recharge rate in dry season. The AVI results suggest that a change in the sea level will have an insignificant impact on groundwater vulnerability compared with the results from the modified SINTACS and GALDIT. The modified SINTACS method could be used as a guideline for the groundwater vulnerability assessment of glacial and deglacial deposits in inland aquifers, and in combination with GALDIT, it could provide a useful tool for assessing groundwater vulnerability to both contamination from sources on the ground surface and to seawater intrusion for shallow unconfined low-lying coastal aquifers under future climate-change conditions. 相似文献
8.
Monitoring and methods to analyse the groundwater quality degradation risk in coastal karstic aquifers (Apulia,Southern Italy) 总被引：1，自引：0，他引：1
A multi-methodological approach based on monitoring and spatio-temporal analysis of groundwater quality changes is proposed.
The presented tools are simple, quick and cost-effective to give service to all sorts of users. The chief purpose of the monitoring
network is the detection of the piezometric or potenziometric level in the aquifer. The spatial and multi-temporal analysis
of usual chemical and physical data provides both an assessment of the spatial vulnerability of the aquifer to seawater intrusion,
defining a salinity threshold between fresh groundwater and brackish groundwater and of the water quality trend in terms of
salinity. The evaluation of the salinity trend or of salinity-correlated parameters highlights the effects of groundwater
mismanagement. The multiparameter logging provides a rapid groundwater quality classification for each well. The whole approach
allows evaluating the effects of current management criteria and designing more appropriate management targets. The Apulian
karstic coastal aquifers have been selected as a case study (Southern Italy). Three types of aquifer zones can be distinguished:
(1) areas with low vulnerability to seawater intrusion, (2) areas with high vulnerability and (3) areas with variable vulnerability
in which the salt degradation largely depends on the ability to manage the well discharge. The water quality degradation caused
by seawater intrusion appears to be a combined effect of an anomalous succession of drought periods observed from about 1980
onwards and increased groundwater pumping, particularly during drought periods. A management criterion based on aquifer zones
is proposed. 相似文献
9.
大连市海水入侵现状与防治措施 总被引：2，自引：0，他引：2
李宝兰 《地质灾害与环境保护》2009,20(3):59-62
海水入侵是沿海地区的环境问题之一。大连是我国北方重要的港口和工业城市．处于三面靠海的半岛地理环境。同时．大连也是一个水资源十分紧缺的城市。自20世纪70年代开采地下水以来．出现了越来越严重的海水入侵问题．海水入侵问题对当地的工农业生产、生态环境及人们的身体健康均造成了不同程度的影响。目前大连市的海水入侵问题已得到控制,基本处于稳定状态。提出了因地制宜的海水入侵防治措施。 相似文献
10.
Saltwater intrusion in coastal regions of North America 总被引：7，自引：3，他引：4
Saltwater has intruded into many of the coastal aquifers of the United States, Mexico, and Canada, but the extent of saltwater intrusion varies widely among localities and hydrogeologic settings. In many instances, the area contaminated by saltwater is limited to small parts of an aquifer and to specific wells and has had little or no effect on overall groundwater supplies; in other instances, saltwater contamination is of regional extent and has resulted in the closure of many groundwater supply wells. The variability of hydrogeologic settings, three-dimensional distribution of saline water, and history of groundwater withdrawals and freshwater drainage has resulted in a variety of modes of saltwater intrusion into coastal aquifers. These include lateral intrusion from the ocean; upward intrusion from deeper, more saline zones of a groundwater system; and downward intrusion from coastal waters. Saltwater contamination also has occurred along open boreholes and within abandoned, improperly constructed, or corroded wells that provide pathways for vertical migration across interconnected aquifers. Communities within the coastal regions of North America are taking actions to manage and prevent saltwater intrusion to ensure a sustainable source of groundwater for the future. These actions can be grouped broadly into scientific monitoring and assessment, engineering techniques, and regulatory approaches. 相似文献
11.
Optimal schemes of groundwater exploitation for prevention of seawater intrusion in the Leizhou Peninsula in southern China 总被引：1，自引：0，他引：1
The Lei-Qiong Depression Zone, near the Leizhou Peninsula in southern China, consists of unconsolidated sediments of 500-3,000 m thickness. Groundwater occurs in a multi-aquifer system in the Leizhou Peninsula. The aquifers receive recharge from precipitation, canal and reservoir infiltration, and discharge mainly through subterranean drainage into the sea. Artificial pumping for drinking and agricultural purposes is another way of groundwater discharge. Groundwater development along the coast faces the threat of seawater intrusion. A quasi-three-dimensional finite element model, containing 457 nodes and 833 elements, has been used to simulate the spatial and temporal distribution of groundwater levels in the three-aquifer system. Verification of various aquifer parameters and boundary conditions was performed with the simulation model. Linear programming models have been developed for groundwater exploitation within the two confined aquifers. The objective function of the models is to maximize the total groundwater pumpage from the confined aquifers. Control of seawater intrusion is examined by restricting the water levels at points along the coast and the withdrawal rates in coastal management cells. A response matrix approach was used in the optimization models. The response matrix was obtained from the simulation model by forecasting drawdown produced by pumping at a unit impulse discharge. Groundwater development in the Leizhou Peninsula can be primarily optimized by allocating the pumping rates of the management cells. 相似文献
12.
海水入侵是沿海地区主要环境地质问题,分析沿海地下水和河水水化学特征,对圈定海水入侵范围及判断影响程度具有重要意义。通过在福建长乐市海水入侵含水层和闽江口海水上溯区采取23件水样进行室内常规离子测试,获得了海水入侵(上溯)区水中主要离子含量。利用海水稀释线分析主要离子与Cl离子之间的相对变化,对比离子实际浓度与理想浓度的差异,分析海水入侵对水化学变化的影响。研究结果显示,随着海水与淡水混合,水化学类型从海水到淡水依次为Na-Cl型水-Na-Cl·HCO3型水-Na·Ca-HCO3·Cl型水-Ca-HCO3型水;引起水化学类型和TDS变化的主要因素为Na+和Cl-的增加;Ca2+、Mg2+高于海水稀释线和理想浓度线,Na+、K+在海水稀释线和理想浓度线上下跳跃：Br-/Cl-与海水稀释线吻合较好,可以作为判断海水入侵范围的依据。 相似文献
13.
A modeling study of seawater intrusion in Alabama Gulf Coast,USA 总被引：4，自引：0，他引：4
A numerical model of variable-density groundwater flow and miscible salt transport is developed to investigate the extent
of seawater intrusion in the Gulf coast aquifers of Alabama, USA. The SEAWAT code is used to solve the density-dependent groundwater
flow and solute transport governing equations. The numerical model is calibrated against the observed hydraulic heads measured
in 1996 by adjusting the zonation and values of hydraulic conductivity and recharge rate. Using the calibrated model and assuming
all the hydrogeologic conditions remain the same as those in 1996, a predictive 40-year simulation run indicates that further
seawater intrusion into the coastal aquifers can occur in the study area. Moreover, the predicted intrusion may be more significant
in the deeper aquifer than the shallower ones. As the population continues to grow and the demand for groundwater pumping
intensifies beyond the 1996 level, it can be expected that the actual extent of seawater intrusion in the future would be
more severe than the model prediction. Better strategies for groundwater development and management will be necessary to protect
the freshwater aquifers from contamination by seawater intrusion.
相似文献
| Jin LinEmail: |
14.
Management of freshwater lenses on small Pacific islands 总被引：3，自引：0，他引：3
The nature of shallow aquifers and the impacts of seawater intrusion in small islands within the Pacific Ocean are reviewed. Many Pacific islands rely on shallow fresh groundwater lenses in highly permeable aquifers, underlain and surrounded by seawater, as their principal freshwater source. It is argued here that, in small islands, the nature of fresh groundwater lenses and their host aquifers coupled with frequent natural and ever-present anthropogenic threats make them some of the most vulnerable aquifer systems in the world. A simple steady-state approximation is used to provide insight into the key climatic, hydrogeological, physiographic, and management factors that influence the quantity of, and saline intrusion into freshwater lenses. Examples of the dynamic nature of freshwater lenses as they respond to these drivers are given. Natural and human-related threats to freshwater lenses are discussed. Long dry periods strongly coupled to sea surface temperatures impact on the quantity and salinity of fresh groundwater. The vulnerability of small island freshwater lenses dictates careful assessment, vigilant monitoring, appropriate development, and astute management. Strategies to aid future groundwater sustainability in small islands are presented and suggested improvements to donor and aid programs in water are also advanced. 相似文献
15.
Vincent E. A. Post Gualbert Oude Essink Adam Szymkiewicz Mark Bakker Georg Houben Emilio Custodio Clifford Voss 《Hydrogeology Journal》2018,26(6):1767-1770
The Salt Water Intrusion Meetings, or SWIMs, are a series of meetings that focus on seawater intrusion in coastal aquifers and other salinisation processes. 2018 marks the 50th year of the SWIM and the 25th biennial meeting. The SWIM proceedings record half a century of research progress on site characterisation, geophysical and geochemical techniques, variable-density flow, modelling, and water management. The SWIM is positioning itself to remain a viable platform for discussing the coastal aquifer management challenges of the next 50 years. 相似文献
16.
Emna Boughariou Moez Bahloul Ikram Jmal Nabila Allouche Jalila Makni Hafedh Khanfir Salem Bouri 《Arabian Journal of Geosciences》2018,11(4):69
Shallow groundwater is one of the main water resources in the arid and semi-arid regions. However, it is threatened by not only the reduced rainfall and recharge capacity, but also the water table drawdown and seawater intrusion. Such factors could cause a deterioration of the water quality and consequently the loss of a valuable hydraulic resource. This study aimed to improve our knowledge on the groundwater chemical quality evolution of the Sfax shallow aquifer, one of the most vulnerable areas in Tunisia, by developing a geochemical study using statistical and numerical methods. Salinization was identified by factorial analysis, PCA, and hierarchical clustering analysis in addition to the numerical MODPATH model. These findings confirmed that the groundwater quality has deteriorated due to natural and anthropogenic processes with a different influence of mineralization factors. They also revealed the location of seawater intrusion by focusing on the most vulnerable areas which are Chaffar and Djbeniana. Methodologically, the use of MODPATH model for seawater intrusion determination might be considered as the backbone for future studies in Tunisian coastal aquifers. The numerical model supports the results obtained by the geochemical analysis. Both methods are valuable tools as they contribute to trend determinations, management, and recovery plans. 相似文献
17.
Natural Hazards - The study dealt with seawater intrusion process in a coastal aquifer system in the Mahanadi river delta region in the east coast of India along the Bay of Bengal. The aquifers of... 相似文献
18.
Adel Kharroubi Faten Tlahigue Belga?em Agoubi Chafai Azri Salem Bouri 《Environmental Earth Sciences》2012,67(7):2089-2100
Coastal aquifers are considered as major sources for freshwater supply worldwide, especially in arid zones. The weak rainfall as well as the intensive extraction of groundwater from coastal aquifers reduce freshwater budget and create local water aquifer depression, causing both seawater intrusion and a threat to groundwater. This phenomenon was observed in the Jerba Island which is located in southeast Tunisia. Jerba??s unconfined aquifer shows high values of groundwater salinity reaching, locally, 17?g/l and a strong contrast between some zones of the aquifer. High pumping rates and weak recharge disturb the natural equilibrium between fresh and saline water causing water salinization in most areas of the island. This study aims at establishing the salinity map of the aquifer and identifying the origin of groundwater salinization. The salinity map shows that zones characterized by low groundwater salinity are located in the center of the study area. High groundwater salinities are observed near the coast and in some parts having low topographic and piezometric levels. Groundwater geochemical characterization, and Br/Cl and Na/Cl ratios suggest that the origin of abnormal salinity is seawater intrusion. Considering groundwater salinity values and Br concentrations, a seawater intrusion map is established. It shows that many areas of the unconfined aquifer are contaminated by mixed groundwater and seawater. The statistical analysis demonstrates that high mineralization of the groundwater is due to gypsum and carbonate dissolution coupled with the mixed groundwater and seawater in many areas. 相似文献
19.
Groundwater recharge dams in arid areas as tools for aquifer replenishment and mitigating seawater intrusion: example of AlKhod, Oman 总被引：1，自引：1，他引：0
Groundwater depletion and seawater intrusion constitute major challenges along coastal aquifers in arid areas. This paper assesses the role of groundwater recharge dams constructed to replenish aquifers and fight seawater intrusion with reference to AlKhod dam, Oman, sited 7 km from the coast on a gravely unconfined aquifer. Water table rise in piezometers located downstream from the dam shows regular patterns correlating with magnitude of wadi flow, whereas upstream piezometers show irregular patterns. Controlled release of water captured by the dam optimizes water percolation and enhances artificial recharge which was estimated in the wet years 1997, 2003 and 2005 as 15, 22 and 27 Mm3, respectively, using water table fluctuation method. Recharge contributed 40–60 % of the total annual abstraction. Groundwater salinity increased in the 1980s and 1990s and the saline/freshwater interface advanced inland, but has receded partially after 1997 (highest rainfall) and completely after 2005 indicated by reduction in electrical conductivity and thickening of freshwater lens. The recession is attributed to the dam’s induced recharge and reduction of pumping in 2004 following the commissioning of Barka desalination plant. Integrating artificial recharge with groundwater resources management is therefore an effective measure to replenish aquifers in arid areas and mitigate seawater intrusion along the coasts. 相似文献
20.
A regional study of saltwater intrusion in southeastern Nigeria based on the analysis of geoelectrical and hydrochemical data. 总被引：1，自引：1，他引：1
Vertical electrical sounding (VES) and hydrochemical data have been used to examine the extent of saltwater intrusion into shallow aquifers (depth<300 m) beneath the coastal plains of southeastern Nigeria underlain by siliciclastic sedimentary rocks of the Cenozoic Niger Delta. The VES data indicate that the coastal regions not affected by saltwater are characterised by K-and H-type geoelectrical curves and models in which high-layer resistivities (in excess of about 100 ohm-m) reflect the presence of freshwater aquifers at depths greater than 5 m below the surface. By contrast, Q-type curves and models denote saltwater-infiltrated islands with the upper boundary of the saline zone at depths of about 25 to 30 m. Chemical analysis results of precipitation and ground water show that, compared to coastal and continental sites, island localities have higher concentrations of major ions (Na+, K+, Ca2+, Mg2+, Cl-, HCO3-, SO42-, NO3) due to saltwater intrusion. In addition, these ions, which also characterise seawater, show very good correlations (>0.70). Furthermore, the coastal sites are marked by Ca-Cl and Ca-HCO3 water types whereas Na-Cl dominated both the islands ( at depths greater than 20 m) and the seawater. This gives an indication of seawater contamination. Seawater contamination is also indicated by the results of five assessment parameters as follows: high chloride concentration (>500 mg/l), high saturation index (halite>10-6), high ionic strength (>0.05), low formation resistivity (<25 ohm-m), and low formation factor (<0.05). Two of these parameters (chloride concentration, ionic strength) have been used to compose an assessment scheme with five major classes (AA, BB, CC, DD, EE) corresponding to various degrees of salinity. Generally in the study area, saltwater contamination is a feature of island locations at depths greater than about 20 m. Water within the inland coastal regions is fresh. 相似文献