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An Assessment of Saltwater Intrusion in Coastal Regions of Lagos, Nigeria
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作者 Obunadike Callistus Akerele D. Daniel +4 位作者 Abiodun O. Pelumi Olisah Somtobe Oloyede Kunle Obunadike S. Echezona Obunadike J. Chinenye 《Journal of Geoscience and Environment Protection》 2024年第1期93-119,共27页
This paper explains various factors that contribute to saltwater intrusion, including overexploitation of freshwater resources and climate change as well as the different techniques essential for effective saltwater i... This paper explains various factors that contribute to saltwater intrusion, including overexploitation of freshwater resources and climate change as well as the different techniques essential for effective saltwater intrusion management. The impact of saltwater intrusion along coastal regions and its impact on the environment, hydrogeology and groundwater contamination. It suggests potential solutions to mitigate the impact of saltwater intrusion, including effective water management and techniques for managing SWI. The application of A.I (assessment index) serves as a guideline to correctly identify wells with SWI ranging from no intrusion, slight intrusion and strong intrusion. The challenges of saltwater intrusion in Lagos and the salinization of wells were investigated using the hydro-chemical parameters. The study identifies four wells (“AA”, “CMS”, “OBA” and “VIL”) as having high electric conductivities, indicating saline water intrusion, while other wells (“EBM”, “IKJ, and “IKO”) with lower electric conductivities, indicate little or no salt-water intrusion, and “AJ” well shows slight intrusion. The elevation of the wells also played a vital role in the SWI across coastal regions of Lagos. The study recommends continuous monitoring of coastal wells to help sustain and reduce saline intrusion. The findings of the study are important for policymakers, researchers, and practitioners who are interested in addressing the challenges of saltwater intrusion along coastal regions. We assessed the SWI across the eight (8) wells using the Assessment Index to identify wells with SWI. Wells in “CMS” and “VIL” has strong intrusions. A proposed classification system based on specific ion ratios categorizes water quality from good (+) to highly (-) contaminated (refer to Table 4). These findings underscore the need for attention and effective management strategies to address groundwater unsuitability for various purposes. 展开更多
关键词 Hydro-Chemical Data Analysis Saline Incursion Aquifer Sustainability and Management Coastal Regions Ground Water intrusion
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Impact of estuarine reclamation projects on saltwater intrusion and freshwater resource 被引量:1
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作者 Hanghang LU Jianrong ZHU +3 位作者 Qing CHEN Ming LI Shunqi PAN Shenliang CHEN 《Journal of Oceanology and Limnology》 SCIE CAS CSCD 2023年第1期38-56,共19页
Estuarine projects can change local topography and influence water transport and saltwater intrusion.The Changjiang(Yangtze)River estuary is a multichannel estuary,and four major reclamation projects have been impleme... Estuarine projects can change local topography and influence water transport and saltwater intrusion.The Changjiang(Yangtze)River estuary is a multichannel estuary,and four major reclamation projects have been implemented in the Changjiang River estuary in recent years:the Xincun Shoal reclamation project(RP-XCS),the Qingcao Shoal reclamation project(RP-QCS),the Eastern Hengsha Shoal reclamation project(RP-EHS),and the Nanhui Shoal reclamation project(RP-NHS).The effects of the four reclamation projects and each project on the saltwater intrusion and water resources in the Changjiang River estuary were simulated in a 3D numerical model.Results show that for a multichannel estuary,local reclamation projects change the local topography and water diversion ratio(WDR)between channels and influence water and salt transport and freshwater utilization in the estuary.During spring tide,under the cumulative effect of the four reclamation projects,the salinity decreases by approximately 0.5in the upper reaches of the North Branch and increases by 0.5-1.0 in the middle and lower reaches of the North Branch.In the North Channel,the salinity decreases by approximately 0.5.In the North Passage,the salinity increases by 0.5-1.0.In the South Passage,the salinity increases by approximately 0.5 in the upper reaches and decreases by 0.2-0.5 on the north side of the middle and lower reaches.During neap tide,the cumulative effects of the four reclamation projects and the individual projects are similar to those during spring tide,but there are some differences.The effects of an individual reclamation project on WDR and saltwater intrusion during spring and neap tides are simulated and analyzed in detail.The cumulative effect of the four reclamation projects favors freshwater usage in the Changjiang River estuary. 展开更多
关键词 reclamation projects saltwater intrusion freshwater resources numerical model Changjiang River estuary
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Impacts of Different Dynamic Factors on the Saltwater Intrusion in the Northern Branch of the Yangtze Estuary 被引量:2
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作者 WANG Jin-hua ZHANG De-bin +1 位作者 ZHANG Wei-sheng ZHANG Jin-shan 《China Ocean Engineering》 SCIE EI CSCD 2019年第6期673-684,共12页
A 3-D baroclinic numerical model is established to study the temporal and spatial distribution of salinity in the Northern Branch(NB) of the Yangtze Estuary(YE) in response to river runoff, wind and currents. The idea... A 3-D baroclinic numerical model is established to study the temporal and spatial distribution of salinity in the Northern Branch(NB) of the Yangtze Estuary(YE) in response to river runoff, wind and currents. The idealized,process-oriented studies show that the lower river runoff in the dry season is the main driving factor for the spilling over from the NB to the Southern Branch(SB). The NB takes longer time to get in dynamic stable state compared with the SB, as the runoff transfers from the wet season to the dry season. The vertical stratification intensity of the NB has obvious periodic phenomena in the dry season, and the stratification strength is enhanced under the action of low runoff and north wind, which further weakens the vertical transport of water. Momentum balance analysis suggested that the landward net flux increases when considering the influence of the moderate north wind, and the landward flux will enhance if considering the boundary current during the spring tide. With the influence of the boundary current, increases the average salinity of the NB, as well as the intrusion degree from the NB to the SB.This indicates that the nearshore ocean current of the Yellow Sea is an important factor affecting the saltwater intrusion in the NB of the YE. 展开更多
关键词 Yangtze Estuary saltwater intrusion ocean currents vertical stratification FVCOM
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Features and evaluation of sea/saltwater intrusion in southern Laizhou Bay 被引量:3
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作者 LIU Hong-wei Klaus Hisby +3 位作者 ZHOU Yang-xiao MA Zhen CHEN She-ming GUO Xu 《Journal of Groundwater Science and Engineering》 2016年第2期141-148,共8页
Understanding the degree of sea/saltwater intrusion in coastal regions is of great significance to treating the intrusion and improving the environment. Based on the character analysis of the sea/saltwater intrusion, ... Understanding the degree of sea/saltwater intrusion in coastal regions is of great significance to treating the intrusion and improving the environment. Based on the character analysis of the sea/saltwater intrusion, five factors were selected in the fuzzy-synthetical evaluation approach to form the index system, so as to evaluate the degree of sea/saltwater intrusion in southern Laizhou Bay. The results show that the sea/saltwater intrusion is stronger in the middle and northern areas and weaker on the sides and in southern area; currently, the intrusion is relatively serious, and the intrusion area has covered about 68.2% of the areas under study, among which the heavily intruded area is over 50%. Based on the factors analysis of the occurrence and development of sea/saltwater intrusion, the thesis proposes treatment measures. 展开更多
关键词 Sea/saltwater intrusion EVALUATION Hydro-chemical indicator Laizhou Bay
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Numerical modeling of saltwater intrusion
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《Global Geology》 1998年第1期88-89,共2页
关键词 Numerical modeling of saltwater intrusion
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Impact of the eastern water diversion from the south to the north project on the saltwater intrusion in the Changjiang Estuary in China 被引量:10
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作者 XU Kun ZHU Jianrong GU Yuliang 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2012年第3期47-58,共12页
The south to the north project(WDP) on the saltwater intrusion in the Changjiang Estuary is studied by the improved three-dimensional(3D) numerical model.The net unit width flux in the Changjiang Estuary as well as th... The south to the north project(WDP) on the saltwater intrusion in the Changjiang Estuary is studied by the improved three-dimensional(3D) numerical model.The net unit width flux in the Changjiang Estuary as well as the sectional salt flux is calculated in the North Branch(NB),the South Branch(SB),the North Channel(NC),the South Channel(SC),the North Passage(NP) and the South Passage(SP),respectively.The net seaward water flux in the SB is reduced,and the net water flux spilling over from the NB to the SB is enhanced after the eastern WDP.Under the mean river discharge condition in the dry season,the net salt flux spilling over from the NB to the SB is increased by 2.09 t/s and 0.52 t/s during the spring and neap tides,respectively,due to the eastern WDP.The saltwater intrusion in the Changjiang Estuary is enhanced by the eastern WDP.Compared with that during the spring tide,the net water diversion ratio during the neap tide in the NC is smaller,and thus the enhancement of the saltwater intrusion by the eastern WDP is smaller in the NC,and larger in the NP and the SP.The tidally averaged surface salinity at the water intakes of the Dongfengxisha Reservoir,the Chenhang Reservoir and the Qingcaosha Reservoir rises both during the spring and neap tides. 展开更多
关键词 eastern WATER DIVERSION from the south to the north project saltwater intrusion Changjiang Estuary numerical calculation the WATER resource
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Investigation of saltwater intrusion and salinity stratification in winter of 2007/2008 in the Zhujiang River Estuary in China 被引量:8
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作者 ZHOU Wei WANG Dongxiao LUO Lin 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2012年第3期31-46,共16页
Saltwater intrusion is a serious environmental problem in the Zhujiang River Estuary(ZRE),which threatens the water supply of fifteen million people.The hydrological observations as well as meteorological and tidal fo... Saltwater intrusion is a serious environmental problem in the Zhujiang River Estuary(ZRE),which threatens the water supply of fifteen million people.The hydrological observations as well as meteorological and tidal forcing in the winter of 2007/2008 were analyzed to examine the saltwater intrusion in the ZRE.The observational results suggest that the maximum vertical difference of salinity can reach 10 in the Humen Channel during neap tide,but is very small in the Hengmen Channel.The vertically averaged salinity from time series stations during spring tide is higher than that during neap tide.A three-dimensional finite difference model was developed based on the environmental fluid dynamic code(EFDC) to study the mechanism of saltwater intrusion and salinity stratification in the ZRE.By analyzing the salt transport and the temporal variation of saltwater intrusion,the authors found that the net salt transport due to the estuarine circulation during neap tide was more than that during spring tide.This caused salt to advance more into the estuary during neap tide.However,saltwater intrusion was stronger during spring tide than that during neap tide because the spring-neap variation in salt transport was small relative to the total length of the saltwater intrusion.The physical mechanism causing this saltwater intrusion was investigated by a series of sensitivity experiments,in order to examine saltwater intrusion in response to river discharge and winds.The freshwater source was a dominant influencing factor to the saltwater intrusion and controlled salinity structure,vertical stratification and length of the saltwater intrusion.The prevailing northeast monsoon during winter could increase the saltwater intrusion in the ZRE.Though the southwest wind was unfavorable to saltwater intrusion during spring tide,it could increase stratification and saltwater intrusion during neap tide. 展开更多
关键词 saltwater intrusion spring tide neap tide salt TRANSPORT
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Impact of seasonal tide variation on saltwater intrusion in the Changjiang River estuary 被引量:11
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作者 裘诚 朱建荣 顾玉亮 《Chinese Journal of Oceanology and Limnology》 SCIE CAS CSCD 2012年第2期342-351,共10页
An improved 3-D ECOM-si model was used to study the impact of seasonal tide variation on saltwater intrusion into the Changjiang River estuary, especially at the bifurcation of the North Branch (NB) and the South Bran... An improved 3-D ECOM-si model was used to study the impact of seasonal tide variation on saltwater intrusion into the Changjiang River estuary, especially at the bifurcation of the North Branch (NB) and the South Branch (SB). The study assumes that the river discharge and wind are constant. The model successfully reproduced the saltwater intrusion. During spring tide, there is water and salt spillover (WSO and SSO) from the NB into the SB, and tidally averaged (net) water and salt fluxes are 985 m3/s and 24.8 ton/s, respectively. During neap tide, the WSO disappears and its net water flux is 122 m3/s. Meanwhile, the SSO continues, with net salt flux of 1.01 ton/s, much smaller than during spring tide. Because the tidal range during spring tide is smaller in June than in March, overall saltwater intrusion is weaker in June than in March during that tidal period. However, the WSO and SSO still exist in June. Net water and salt fluxes in that month are 622 m3/s and 15.35 ton/s, respectively, decreasing by 363 m3/s and 9.45 ton/s over those in March. Because tidal range during neap tide is greater in June than in March, saltwater intrusion in June is stronger than in March during that tidal period. The WSO and SSO appear in June, with net water and salt fluxes of 280 m3/s and 8.55 ton/s, respectively, increasing by 402 m3/s and 7.54 ton/s over those in March. Saltwater intrusion in the estuary is controlled by the river discharge, semi-diurnal flood-ebb tide, semi-monthly spring or neap tide, and seasonal tide variation. 展开更多
关键词 盐水入侵 长江河口 潮流变化 季节性 SSO 盐通量 海水倒灌 海水入侵
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Modeling of the Groundwater Flow and Saltwater Intrusion in the Coastal Aquifer of Fum Al Wad, Province of Laayoun, Morocco 被引量:3
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作者 Mohamed El Mokhtar Mohamed Chibout +3 位作者 Bouabid El Mansouri Jamal Chao Malika Kili Sidi Mokhtar El Kanti 《International Journal of Geosciences》 2018年第1期71-92,共22页
Saltwater intrusion caused by groundwater over-exploitation from coastal aquifers poses a severe problem in many regions. The Fum Al Wad aquifer is located between Atlantic Ocean in the West and Laayoun in the East. T... Saltwater intrusion caused by groundwater over-exploitation from coastal aquifers poses a severe problem in many regions. The Fum Al Wad aquifer is located between Atlantic Ocean in the West and Laayoun in the East. This aquifer covers an area of 250 Km2, and represents an essential water resource for Laayoun city and the periphery regions. It is heavily exploited for water supply, agriculture and industry. The freshwater-saltwater interface is affected by groundwater extraction by public supplies, irrigation wells, and domestic wells in the coastal of this aquifer. The position of the interface is controlled by several factors: these include precipitation, recharge rate, dryness, evapotranspiration, hydraulic conductivity and hydraulic head. Landward migration of the interface freshwater-saltwater often results in a significant decrease in the water resources available for coastal communities. The volume pumped by public for irrigation and the domestic usage in 2010-2011 is estimated 2.5 Mm3/year, and in 2015 about 2.91 Mm3/year only for domestic usages. The objectives of this work are to model the groundwater flow and saltwater intrusion in the coastal aquifer of Fum Al Wad, by SEAWAT-2000 program which coupled both the version of MODFLOW-2000 and MT3DMS. They are designed to simulate variable-density groundwater flow and solute transport in three dimensions. The model is calibrated for hydraulic conductivity, specific yield, porosity, and recharge rate as well as dispersivity coefficient. The result of simulation of the hydrodynamic model during the period of 1986-2015 has revealed a piezometric drawdown with 2.3 m approximately at the level of the pumping zone. Furthermore, this piezometric depression is caused by excessive pumping of the various uses of water and its corresponding that has resulted in the migration of the saltwater intrusion into freshwater with 4.3 km approximately. The simulations result for scenarios 2020 and 2030 of Fum Al Wad aquifer showed a vertical decrease of the piezometric head (about 2.5 m) in 2030, but the saltwater intrusion has advanced diagonally to reach 4.7 km under the freshwater of groundwater of this aquifer. 展开更多
关键词 Fum AL WAD AQUIFER Over-Exploitation Pumping WELLS saltwater intrusion Piezometric Head WATER-TABLE
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A Modeling Study on Saltwater Intrusion to Western Four Watercourses in the Pearl River Estuary 被引量:1
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作者 程香菊 詹威 +1 位作者 郭振仁 袁丽蓉 《China Ocean Engineering》 SCIE EI 2012年第4期575-590,共16页
Saltwater intrusion has been serious in the Pearl River estuary in recent years. For better understanding and analysis of the saltwater movement to the estuary, the three-dimensional Finite-Volume Coastal Ocean Model ... Saltwater intrusion has been serious in the Pearl River estuary in recent years. For better understanding and analysis of the saltwater movement to the estuary, the three-dimensional Finite-Volume Coastal Ocean Model (FVCOM) is made to simulate the salinity intrusion to the four western watercourses in the Pearl River estuary under three semilunar conditions. With the measured and simulated Root Mean Square Error (RMSE) and the mean absolute percentage error of water level and salinity at multiple sites, the results show that the numerical water levels, salinity and flow velocities are in agreement with the measured data. It is acceptable and feasible to apply the FVCOM to simulate the salt water intrusion in the western four watercourses of the Pearl River. With the numerical data, the time and spatial movement patterns of saltwater intrusion along the Modao watercourse are analyzed. The salinity contour reaches its peak generally during 3-5 days before the spring tide. The salinity stratification is more obvious in the period of ebb tide than that in the rising tide whether in the spring or neap tides. Salt fluxes reflect changes of salt into the estuary, and the change rules are close to the rules of salinity intrusion. 展开更多
关键词 珠江口 模拟 水道 均方根误差 盐度分层 倒灌 咸潮 西方
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Effect of saltwater intrusion on groundwater environment in Weihe River downstream, Shandong Province, China
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作者 MENG Yong-hui WANG Ji-ning +4 位作者 YU De-Jie ZHANG Li-xia FENG Zai-min YAN Tang ZHOU Yong 《Journal of Groundwater Science and Engineering》 2019年第3期245-252,共8页
Based on the geological and hydrogeological conditions along with dynamic changes of groundwater level,this paper analyzes the hydrodynamic characteristics of saltwater intrusion in the study area.According to monitor... Based on the geological and hydrogeological conditions along with dynamic changes of groundwater level,this paper analyzes the hydrodynamic characteristics of saltwater intrusion in the study area.According to monitoring data of groundwater quality,the distribution characteristics of macro component are analyzed,and then fuzzy comprehensive evaluation method is adopted to evaluate the impact of saltwater intrusion on groundwater environment.Concerning the influence degree of groundwater environment,the study area is divided into brine area,seriously influenced area,moderately influenced zone,slightly influenced zone and uninfluenced zone.The results can offer references for prevention and control of saltwater intrusion as well as the protection of water resources. 展开更多
关键词 saltwater intrusion BRINE resources HYDRODYNAMIC characteristics GROUNDWATER macro component GROUNDWATER environment
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Groundwater Quality Assessment Based on WQI and Its Vulnerability to Saltwater Intrusion in a Coastal City, Iran
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作者 Salman Tavassoli Farzad Mohammadi 《Journal of Geoscience and Environment Protection》 2017年第6期88-98,共11页
The purpose of this paper was to assess the quality of groundwater in Behshahr (Iran) based on water quality index (WQI). Sixteen water samples from this coastal aquifer were collected and analyzed to study physico-ch... The purpose of this paper was to assess the quality of groundwater in Behshahr (Iran) based on water quality index (WQI). Sixteen water samples from this coastal aquifer were collected and analyzed to study physico-chemical parameters such as pH, hardness, chloride (Cl), electrical conductivity (EC) and total dissolved solids (TDS). The results showed that the annual average of TDS value increased by 343 mg/l between 1999 and 2015 due to anthropogenic activities. According to WQI, it was concluded that the groundwater quality degraded over the last sixteen-year period so that the percentage of samples identified as “good water” decreased by 18.5% and on the other hand, alas, the percentage of “poor water” quality soared by nearly 12.5%. Correspondence of WQI distribution diagram with that of chloride-bicarbonate ratio attests to the significant contribution of saltwater intrusion to groundwater quality deterioration in this area. 展开更多
关键词 GROUNDWATER QUALITY Water QUALITY Index PHYSICO-CHEMICAL Parameters saltwater intrusion COASTAL Aquifers
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Assessment of Saltwater Intrusion and Discharges to a Wetland with a 3D Transient Variable Density Flow Model: The Coastal Plane Oropesa-Torreblanca Aquifer, Spain
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作者 Ignacio Sanz-Garrido José E. Capilla 《Journal of Water Resource and Protection》 2015年第9期749-768,共20页
The proper characterization of coastal aquifers requires modeling variable density flow effects. However, most models estimate processes as saline intrusion based on 2D models with constant density and are rarely cali... The proper characterization of coastal aquifers requires modeling variable density flow effects. However, most models estimate processes as saline intrusion based on 2D models with constant density and are rarely calibrated to honor salinity measurements. These facts limit the model predictions reliability, affecting the estimated hydrodynamic parameters, external stresses, and other model outputs that can be critical for planning or management decisions. This paper describes the re-assessment of a coastal aquifer model (Oropesa-Torreblanca, eastern Spain) subjected to moderate-to-high saline intrusion with a transient 3D variable density flow model. Previous models were based on 2D low-resolution grids without variable density effects. The new model honors the observed trends of both piezometric and salinity data. Results show the importance of the variable density effects having on critical outputs as sea intrusion and the discharges to a local wetland of high environmental value. The widespread intrusion process and its current stabilization are confirmed but, compared to previous models, the annual average intrusion is 156% higher, discharge to the wetland increases 30%, and the inflows from neighboring formations increase 22%. The more accurate aquifer models, as well as the new discharges and intrusion estimations, are important contributions for future water and environmental planning decisions in the area. 展开更多
关键词 SALINIZATION intrusion Variable Density Calibration WETLAND
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Saltwater Intrusion in Jizan Coastal Zone, Southwest Saudi Arabia, Inferred from Geoelectric Resistivity Survey
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作者 Saad Mogren 《International Journal of Geosciences》 2015年第3期286-297,共12页
This work focuses on the causes of water quality deterioration in the coastal plain of Jizan area, southwest Saudi Arabia using vertical electrical sounding (VES) surveys. Schlumberger electrode array is used in the s... This work focuses on the causes of water quality deterioration in the coastal plain of Jizan area, southwest Saudi Arabia using vertical electrical sounding (VES) surveys. Schlumberger electrode array is used in the study with the current electrode spacing ranging from 400 to 600 m to delineate the thickness of the shallow aquifer and its possible interaction with the sea water. The differences in resistivity are associated with the variations in lithology and groundwater saturation and salinity. The interpretation of VES curves reveals low resistivity zones characterizing the study area. These zones reflect saline water intrusion in the coastal aquifer. Generally, it is observed that the resistivity of saturated zone decreases towards the sea, indicating the influence of seawater. Based on the interpretation of the constructed resistivity pseudo-sections and 1-D sequential inversion models, three factors are identified to control the seawater intrusion into the shallow groundwater aquifers: 1) presence of faults that contribute extensively in the seawater intrusion as the seawater invades the coastal aquifers through the crushed rocks in fault zones related to the Red Sea rifting, 2) over-withdrawal of groundwater from the coastal aquifers, resulting in saline water intrusion from the sea into the freshwater aquifer, and 3) the lithological variation where the alluvial sediments of the ancient buried wadi (dry valley) channels provide potential pathways for saltwater intrusion and make a hydraulic connection between the aquifer and the sea water. 展开更多
关键词 GEOELECTRIC RESISTIVITY Seawater intrusion Jizan Area SAUDI ARABIA
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PARAMETERS IDENTIFICATION IN A SALTWATER INTRUSION PROBLEM
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作者 李季 Carole ROSIER 《Acta Mathematica Scientia》 SCIE CSCD 2020年第5期1563-1584,共22页
This article is devoted to the identification, from observations or field measurements, of the hydraulic conductivity K for the saltwater intrusion problem in confined aquifers. The involved PDE model is a coupled sys... This article is devoted to the identification, from observations or field measurements, of the hydraulic conductivity K for the saltwater intrusion problem in confined aquifers. The involved PDE model is a coupled system of nonlinear parabolic-elliptic equations completed by boundary and initial conditions. The main unknowns are the saltwater/freshwater interface depth and the freshwater hydraulic head. The inverse problem is formulated as an optimization problem where the cost function is a least square functional measuring the discrepancy between experimental data and those provided by the model.Considering the exact problem as a constraint for the optimization problem and introducing the Lagrangian associated with the cost function, we prove that the optimality system has at least one solution. Moreover, the first order necessary optimality conditions are established for this optimization problem. 展开更多
关键词 parameters identification optimization problem strongly coupled system nonlinear parabolic equations seawater intrusion
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Numerical simulation on the process of saltwater intrusion and its impact on the suspended sediment concentration in the Changjiang(Yangtze)estuary
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作者 庞重光 赵恩宝 杨扬 《Chinese Journal of Oceanology and Limnology》 SCIE CAS CSCD 2010年第3期609-618,共10页
To study the relationship between sediment transportation and saltwater intrusion in the Changjiang (Yangtze) estuary, a three-dimensional numerical model for temperature, salinity, velocity field, and suspended sedim... To study the relationship between sediment transportation and saltwater intrusion in the Changjiang (Yangtze) estuary, a three-dimensional numerical model for temperature, salinity, velocity field, and suspended sediment concentration was established based on the ECOMSED model. Using this model, sediment transportation in the flood season of 2005 was simulated for the Changjiang estuary. A comparison between simulated results and observation data for the tidal level, flow velocity and direction, salinity and suspended sediment concentration indicated that they were consistent in overall. Based on model verification, the simulation of saltwater intrusion and its effect on sediment in the Changjiang estuary was analyzed in detail. The saltwater intrusion in the estuary including the formation, evolution, and disappearance of saltwater wedge and the induced vertical circulation were reproduced, and the crucial impact of the wedge on cohesive and non-cohesive suspended sediment distribution and transportation were successfully simulated. The result shows that near the salinity front, the simulated concentrations of both cohesive and non-cohesive suspended sediment at the surface layer had a strong relationship with the simulated velocity, especially when considering a 1-hour lag. However, in the bottom layer, there was no obvious correlation between them, because the saltwater wedge and its inducing vertical circulation may have resuspended loose sediment on the bed, thus forming a high-concentration area near the bottom even if the velocity near the bottom was very low during the transition phase from flood to ebb. 展开更多
关键词 悬浮泥沙浓度 盐水入侵 数值模拟 长江 河口
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Modeling of the Saltwater Intrusion Using the Level Set Method. Application to Henry’s Problem
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作者 Joachna Meya Loua-Bouayi Christian Tathy Adolphe Kimbonguila Manounou 《Computational Water, Energy, and Environmental Engineering》 2022年第1期11-33,共23页
The salt intrusion phenomenon is caused by </span><u><span style="font-family:Verdana;">overexploitation</span></u><span style="font-family:Verdana;"> of aquifer... The salt intrusion phenomenon is caused by </span><u><span style="font-family:Verdana;">overexploitation</span></u><span style="font-family:Verdana;"> of aquifers in coastal areas. This physical phenomenon has been the subject of numerous </span><span style="font-family:Verdana;">studies and numerous methods have been proposed, with the aim of protecting the quality of the water in these aquifers. This work proposes a two-dimensional</span><span style="font-family:Verdana;"> saline intrusion model using the sharp interface approach and the level set method. It consists of a parabolic equation modeling the underground flow and a hyperbolic Equation (the level set equation) which makes it possible to track the evolution of the interface. High</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">-</span></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;">order numerical schemes such as the space scheme </span><u><span style="font-family:Verdana;">WENO5</span></u><span style="font-family:Verdana;"> and the third</span></span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">-</span></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;">order time scheme </span><u><span style="font-family:Verdana;">TVD</span></u><span style="font-family:Verdana;">-</span><u><span style="font-family:Verdana;">RK</span></u><span style="font-family:Verdana;"> were used for the numerical resolution of the hyperbolic equation. To limit the tightening of the contour curves of the level set function, the </span><u><span style="font-family:Verdana;">redistanciation</span></u><span style="font-family:Verdana;"> or </span><u><span style="font-family:Verdana;">reinitialization</span></u><span style="font-family:Verdana;"> algorithm proposed by </span><u><span style="font-family:Verdana;">Sussma </span><i><span style="font-family:Verdana;">et al.</span></i></u><span style="font-family:Verdana;"> (1994) was used. To ensure the effectiveness and reliability of the proposed method, two tests relating to the standard Henry problem and the modified Henry problem were performed. Recall that Henry’s problem uses the variable density modeling approach in a confined and homogeneous aquifer. By comparing the results obtained by the level set method with </span><u><span style="font-family:Verdana;">reinitialization</span></u><span style="font-family:Verdana;"> (</span><u><span style="font-family:Verdana;">LSMR</span></u><span style="font-family:Verdana;">) and those obtained by Henry (1964), and by Simpson and Clement (2004), we see in the two test cases that the level set method reproduces well the toe, the tip and the </span><u><span style="font-family:Verdana;">behaviour</span></u><span style="font-family:Verdana;"> of the interface. These results correspond to the results obtained by </span><u><span style="font-family:Verdana;">Abarca</span></u><span style="font-family:Verdana;"> for Henry’s problem with constant dispersion coefficients. The results obtained with </span><u><span style="font-family:Verdana;">LSMR</span></u><span style="font-family:Verdana;">, reproduced the interface with a slight spacing compared to those obtained by Henry. According to </span><u><span style="font-family:Verdana;">Abarca</span></u><span style="font-family:Verdana;"> (2006), this spacing is due to the absence of the longitudinal and </span><u><span style="font-family:Verdana;">transversal</span></u><span style="font-family:Verdana;"> dispersion coefficients in the model. 展开更多
关键词 Confined Aquifer Seawater intrusion Level Set Method Sharp Interface Henry Problem
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Strengthening Network Security: Deep Learning Models for Intrusion Detectionwith Optimized Feature Subset and Effective Imbalance Handling
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作者 Bayi Xu Lei Sun +2 位作者 Xiuqing Mao Chengwei Liu Zhiyi Ding 《Computers, Materials & Continua》 SCIE EI 2024年第2期1995-2022,共28页
In recent years,frequent network attacks have highlighted the importance of efficient detection methods for ensuring cyberspace security.This paper presents a novel intrusion detection system consisting of a data prep... In recent years,frequent network attacks have highlighted the importance of efficient detection methods for ensuring cyberspace security.This paper presents a novel intrusion detection system consisting of a data prepro-cessing stage and a deep learning model for accurately identifying network attacks.We have proposed four deep neural network models,which are constructed using architectures such as Convolutional Neural Networks(CNN),Bi-directional Long Short-Term Memory(BiLSTM),Bidirectional Gate Recurrent Unit(BiGRU),and Attention mechanism.These models have been evaluated for their detection performance on the NSL-KDD dataset.To enhance the compatibility between the data and the models,we apply various preprocessing techniques and employ the particle swarm optimization algorithm to perform feature selection on the NSL-KDD dataset,resulting in an optimized feature subset.Moreover,we address class imbalance in the dataset using focal loss.Finally,we employ the BO-TPE algorithm to optimize the hyperparameters of the four models,maximizing their detection performance.The test results demonstrate that the proposed model is capable of extracting the spatiotemporal features of network traffic data effectively.In binary and multiclass experiments,it achieved accuracy rates of 0.999158 and 0.999091,respectively,surpassing other state-of-the-art methods. 展开更多
关键词 intrusion detection CNN BiLSTM BiGRU ATTENTION
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Artificial Immune Detection for Network Intrusion Data Based on Quantitative Matching Method
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作者 CaiMing Liu Yan Zhang +1 位作者 Zhihui Hu Chunming Xie 《Computers, Materials & Continua》 SCIE EI 2024年第2期2361-2389,共29页
Artificial immune detection can be used to detect network intrusions in an adaptive approach and proper matching methods can improve the accuracy of immune detection methods.This paper proposes an artificial immune de... Artificial immune detection can be used to detect network intrusions in an adaptive approach and proper matching methods can improve the accuracy of immune detection methods.This paper proposes an artificial immune detection model for network intrusion data based on a quantitative matching method.The proposed model defines the detection process by using network data and decimal values to express features and artificial immune mechanisms are simulated to define immune elements.Then,to improve the accuracy of similarity calculation,a quantitative matching method is proposed.The model uses mathematical methods to train and evolve immune elements,increasing the diversity of immune recognition and allowing for the successful detection of unknown intrusions.The proposed model’s objective is to accurately identify known intrusions and expand the identification of unknown intrusions through signature detection and immune detection,overcoming the disadvantages of traditional methods.The experiment results show that the proposed model can detect intrusions effectively.It has a detection rate of more than 99.6%on average and a false alarm rate of 0.0264%.It outperforms existing immune intrusion detection methods in terms of comprehensive detection performance. 展开更多
关键词 Immune detection network intrusion network data signature detection quantitative matching method
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Lightweight Intrusion Detection Using Reservoir Computing
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作者 Jiarui Deng Wuqiang Shen +4 位作者 Yihua Feng Guosheng Lu Guiquan Shen Lei Cui Shanxiang Lyu 《Computers, Materials & Continua》 SCIE EI 2024年第1期1345-1361,共17页
The blockchain-empowered Internet of Vehicles(IoV)enables various services and achieves data security and privacy,significantly advancing modern vehicle systems.However,the increased frequency of data transmission and... The blockchain-empowered Internet of Vehicles(IoV)enables various services and achieves data security and privacy,significantly advancing modern vehicle systems.However,the increased frequency of data transmission and complex network connections among nodes also make them more susceptible to adversarial attacks.As a result,an efficient intrusion detection system(IDS)becomes crucial for securing the IoV environment.Existing IDSs based on convolutional neural networks(CNN)often suffer from high training time and storage requirements.In this paper,we propose a lightweight IDS solution to protect IoV against both intra-vehicle and external threats.Our approach achieves superior performance,as demonstrated by key metrics such as accuracy and precision.Specifically,our method achieves accuracy rates ranging from 99.08% to 100% on the Car-Hacking dataset,with a remarkably short training time. 展开更多
关键词 Echo state network intrusion detection system Internet of Vehicles reservoir computing
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