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《物探化探计算技术》2016,(1)
近年来海(咸)水入侵已成为影响居民生活、制约工农业发展的重大问题,确定咸淡水界面是治理海(咸)水入侵的重要前提。根据咸淡水的电性差异,针对两种典型的咸水入侵地电模型进行正、反演计算,并研究了不同因素对电阻率法测量咸淡水界面的影响。结果表明:1电阻率法数值模拟可以较好地反映咸淡水界面的位置及形态;2咸化程度和现场实测范围内的粘土层电阻率变化对咸淡水界面的测量无明显影响;3测量极距主要影响反演剖面的分辨率,极距越小,分辨率越高。 相似文献
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海岸带地下咸水和淡水之间界面的形态特征以及运移规律是研究海水入侵现象的重要内容。介绍了最近几十年来国内外海岸带咸淡水界面的研究进展,对国内外咸淡水界面的研究现状进行了分析,系统地总结了解析法、数值法和实验方法等在咸淡水界面研究中的应用及取得的相应成果。解析法可以近似简便地确定咸淡水界面的位置与移动规律,数值法在刻画复杂的水文地质条件和人为因素下咸淡水界面的运移规律更为准确,实验方法可以直观地观察界面的形态和移动特点,电导率法能有效地监测咸淡水界面因潮汐作用而引起的微小变动。这些成果丰富和发展了海岸带咸淡水界面理论,对于海岸带地下淡水资源的开发利用和环境保护具有重要的理论意义和实用价值。 相似文献
4.
电阻率法在防治莱州湾地区海水入侵中的应用 总被引：4，自引：0，他引：4
阐述电阻率法在莱州湾地区海水入侵防治研究中应用的理论依据、监测指标.对海、咸水入侵区地层电阻率的变化规律,咸、淡水界面的确定,圈定海水入侵通道及界面运移规律做了分析. 相似文献
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开采条件下河北平原中部咸淡水界面下移 总被引：3，自引：0，他引：3
河北平原中部上层咸水入侵下层淡水已造成局部地下水污染,本文调查统计了地下水质监测资料和2700多眼深井孔的测井物探资料。以水化学方法和数理统计方法,从水文地质条件和地下水开采利用状况入手,对研究区咸淡水界面下移的机理进行了分析。结果认为,咸淡水界面从20世纪70年代以来年均下移约0.4m,开采地下水造成上下层水头压力变化,加大上部浅层水向下越流是其主要原因之一。 相似文献
7.
为研究黄河下游惠民地区地下咸水分布特征,在该区域开展了直流电阻率法测量工作。通过电阻率测井确定区内咸水层视电阻率数值分布范围和咸—淡水界面变化特征,以此约束电阻率测深数据的分析,提高对咸水层分布解释的准确率。结果表明：研究区地下咸水层顶界面埋深主要位于20～50 m区间,局部发育至浅地表;咸水层底界面推断埋深主要分布在160～300 m区间,近似NW走向逐渐变浅。经后期水样调查和钻探验证,推测的地下咸水分布特征与实际情况基本一致,表明直流电阻率法在地下咸水分布特征研究中具有较好的应用效果。 相似文献
8.
海岸带咸淡水界面位置确定方法的介绍 总被引：1，自引：1，他引：0
Ghyben-Herzberg公式依赖潜水位确定海岸带咸淡水界面位置,被广泛应用但存在误差。Hubbert公式严格描述突变界面问题的水头和界面位置之间的关系,但在实际中难以应用。通过考察咸淡水界面之下咸水带任意点的压力平衡关系和咸水带及淡水带任意点的水头描述得知,当地下水流处于稳定状态且满足Dupuit假设时,可以根据同一垂直线上界面之下咸水带任意点(含界面)的咸水测压水头和界面之上淡水带任意点(自潜水面至界面)的淡水测压水头确定滨海均质各向同性潜水含水层咸淡水界面的位置。Ghyben-Herzberg公式是这一方法的特例,描述界面位置的Hubbert公式也是该方法的一个特例。这一方法需要两个相邻的分别揭露淡水带和咸水带的测压孔。 相似文献
9.
运用三维变密度潮汐效应模型确定滨海含水系统的海底等效边界——山东烟台夹河中下游地区为例 总被引：3，自引：1，他引：3
确定咸淡水界面的位置是滨海地区海水入侵研究的主要任务之一。对于天然条件承压含水层而言，含水层顶板向海底延伸的距离直接影响了咸淡水界面的位置，它可以通过承压含水层中地下水的潮汐效应信息来确定。考虑到咸淡水之间密度的差异，建立了山东省夹河中下游地区滨海含水系统地下水三维变密度潮汐效应模型。通过反复对比潮汐效应观测中的地下水水头波动与模型计算出的水头波动，确定了滨海承压含水系统的海底边界。同时，也初步估计出海区与近海陆区含水层的水文地质参数。 相似文献
10.
《地下水》2021,(4)
利用成都高新东区(空港新城)城市地下空间资源地质调查项目实施的188个深度160～220 m钻孔开展分层取样、井液电阻率测试、岩芯分层TDS测试等综合方法查明成都东部新区空港新城咸淡水界面的平面分布特征、垂向分布特征及水化学特征。结果显示:(1)研究区咸淡水界面平面分布呈东西分带特点。(2)从垂向分布特征看,埋深0～15 m范围内,全区基本无微咸水分布;埋深15～20 m范围内,微咸水点零星出现,至埋深20 m后会大量增加;15～70 m埋深内,微咸水普遍分布在地层膏盐分布区,而在非膏盐分布区基本不存在微咸水;在埋深70m以下,丘陵区全区均有微咸水分布的现象。(3)研究区咸水化学成分一般主要以硫酸盐(钠、钙)为主。但在埋深70 m以下非膏盐分布区咸水水化学特征主要以氯酸盐为主,其次为硫酸盐。随着埋深增加,咸水矿化度总体呈上升的趋势,埋深50 m和80 m以下分别出现咸水和卤水现象,但矿化度随深度递增的线性规律并不明显。研究结果为成都东部新区空港新城地下空间利用规划提供基础资料,为广大红层丘陵区查明咸淡水分布规律提供了借鉴。 相似文献
11.
Seawater intrusion in the Salalah plain aquifer,Oman 总被引：2，自引：0，他引：2
Salalah is situated on a fresh water aquifer that is replenished during the annual monsoon season. The aquifer is the only
source of water in Salalah city. The rainfall and mist precipitation in the Jabal AlQara recharges the plain with significant
renewable fresh groundwater that has allowed agricultural and industrial development to occur. In Salalah city where groundwater
has been used extensively since the early 1980s for agricultural, industrial and municipal purposes, the groundwater has been
withdrawn from the aquifer more rapidly than it can be replenished by natural recharge. The heavy withdrawal of large quantities
of the groundwater from the aquifer has led to the intrusion of seawater. Agricultural activities utilize over 70% of the
groundwater. For the study of the saltwater intrusion, the area has been divided into four strips, A, B, C and D, on the basis
of land-use in the area. Water samples were collected from 18 water wells. Chemical analysis of major ions and pollution parameters
in the groundwater was carried out and compared to the previous observed values. The electrical conductivity and chloride
concentrations were highest in the agricultural and residential strips and Garziz grass farm. Before 1992 the aquifer was
in a steady state, but presently (2005) the groundwater quality in most of the agricultural and residential strips does not
meet drinking water standards. In addition, model simulations were developed with the computer code MODFLOW and MT3DMS for
solute transport to determine the movement of the freshwater/saltwater interface. The study proposes the protection of the
groundwater in Salalah plain aquifer from further encroachment by artificial recharge with reclaimed water, preferably along
the Salalah coastal agricultural strip. This scheme can also be applied to other regions with similar conditions. 相似文献
12.
J. Rey J. Martínez G. G. Barberá J. L. García-Aróstegui J. García-Pintado D. Martínez-Vicente 《Environmental Earth Sciences》2013,70(5):2271-2282
Anthropogenic pressure influences the two-way interactions between shallow aquifers and coastal lagoons. Aquifer overexploitation may lead to seawater intrusion, and aquifer recharge from rainfall plus irrigation may, in turn, increase the groundwater discharge into the lagoon. We analyse the evolution, since the 1950s up to the present, of the interactions between the Campo de Cartagena Quaternary aquifer and the Mar Menor coastal lagoon (SE Spain). This is a very heterogeneous and anisotropic detrital aquifer, where aquifer–lagoon interface has a very irregular geometry. Using electrical resistivity tomography, we clearly identified the freshwater–saltwater transition zone and detected areas affected by seawater intrusion. Severity of the intrusion was spatially variable and significantly related to the density of irrigation wells in 1950s–1960s, suggesting the role of groundwater overexploitation. We distinguish two different mechanisms by which water from the sea invades the land: (a) horizontal advance of the interface due to a wide exploitation area and (b) vertical rise (upconing) caused by local intensive pumping. In general, shallow parts of the geophysical profiles show higher electrical resistivity associated with freshwater mainly coming from irrigation return flows, with water resources mostly from deep confined aquifers and imported from Tagus river, 400 km north. This indicates a likely reversal of the former seawater intrusion process. 相似文献
13.
Determining groundwater protection zones for the Quaternary aquifer of northeastern Nile Delta using GIS-based vulnerability mapping 总被引：3，自引：2，他引：1
Hossam H. Elewa Ragaa E. Shohaib Atef A. Qaddah Ahmad M. Nousir 《Environmental Earth Sciences》2013,68(2):313-331
The area of study lies at the northeastern part of Nile Delta. Global shoreline regression and sea-level rise have their own-bearing on the groundwater salinization due to seawater intrusion. A new adopted approach for vulnerability mapping using the hydrochemical investigations, geographic information system and a weighted multi-criteria decision support system (WMCDSS) was developed to determine the trend of groundwater contamination by seawater intrusion. Six thematic layers were digitally integrated and assigned different weights and rates. These have been created to comprise the most decisive criteria used for the delineation of groundwater degradation due to seawater intrusion. These criteria are represented by the total dissolved solids, well discharge, sodium adsorption ratio, hydrochemical parameter (Cl/HCO3), hydraulic conductivity and water types. The WMCDSS modeling was tried, where a groundwater vulnerability map with four classes ranging from very low to high vulnerability was gained. The map pinpointed the promising localities for groundwater protection, which are almost represented by the very low or low vulnerability areas (53.69 % of the total study area). The regions having high and moderate groundwater vulnerability occupy 46.31 % of total study area, which designate to a deteriorated territory of groundwater quality, and needs special treatment and cropping pattern before use. However, the moderate groundwater vulnerability class occupies an area of about 28.77 % of the total mapped area, which highlighted the need for certain management practices to prevent the saltwater intrusion from expanding further to the south. There was a good correlation of the constructed vulnerability map with the recently gathered water quality data and hydrochemical facies evolution. The plotting of water quality data on Piper trilinear diagram revealed the evolution of freshwater into the mixing and the saline zones as an impact of seawater intrusion, which validates the model results. 相似文献
14.
Ahmed Abdulameer Jassim M. Thabit Firas H. AL-Menshed Broder Merkel 《Environmental Earth Sciences》2018,77(17):619
Electrical resistivity surveying for delineating seawater intrusion was performed in the Dibdibba aquifer in the area between the cities of Al-Zubair–Safwan and Al-Zubair–Umm Qasr in the vicinity of Khor AL-Zubair Channel, Basrah governorate, southern Iraq. Fourteen 2D resistivity profiles with a total length of 14 km were collected in the study area. The resistivity sections were compared with lithological data extracted from 11 boreholes. Thirty-nine groundwater samples were collected within the area and analyzed for chemical constituents; internal hydrogeological reports and unpublished studies were also evaluated. Results reveal the existence of three major resistivity layers, ranging from 0.1 to 130 Ωm at various depths and locations. The first layer has very low electrical resistivity (0.1–5 Ωm) representing a layer saturated with saltwater intruded from Khor AL-Zubair Channel. The second layer shows resistivity in the range of 5–130 Ωm, attributed to a transition zone and an unaffected zone saturated with brackish groundwater. The last resistivity layer (<?3 Ωm) represents coarse-grain sediments saturated with saline groundwater. Furthermore, a hard clay bed (Jojab) appears with a resistivity of 3–7 Ωm in all 2D imaging lines within a depth of 20–28 m. Electrical conductivity (EC) measurements from seven wells collected in 2014 and 2016 show a positive EC difference increasing landward with an average increase of 1927 µS/cm. In addition, six chemical relationships (Na/Cl, [Ca?+?Mg]/[HCO3?+?SO4], SO4/HCO3, SO4/Cl, Mg/Ca and Cl/[HCO3?+?CO3]) are used to detect the source of salinity in groundwater. This study proves that extensive use of high-resolution 2D imaging sections, alongside lithological and hydrogeological data, can serve as a useful tool to delineate the boundaries between aquifers, identify hydraulic boundaries between groundwater with different salinities and allocate hard clay layers between the upper and lower Dibdibba aquifer. In general, the combination of 2D imaging and hydrochemistry enables conceptualization of the hydrogeological situation in the subsurface and characterization of the salinity source, here seawater intrusion, in the study area. There have been no studies published so far on the characteristics of saltwater intrusion in the study area, and this study is considered to be important for monitoring and studying the intrusion and regression of seawater. 相似文献
15.
Saumen Maiti Gautam Gupta Vinit C. Erram Ram Krishna Tiwari 《Environmental Earth Sciences》2013,68(3):779-794
Modeling resistivity profiles, especially from hard rock areas, is of specific relevance for groundwater exploration. A method based on Bayesian neural network (BNN) theory using a Hybrid Monte Carlo (HMC) simulation scheme is applied to model and interpret direct current vertical electrical sounding measurements from 28 locations around the Malvan region, in the Sindhudurg district, southwest India. The modeling procedure revolves around optimizing the objective function using the HMC based sampling technique which is followed by updating each trajectory by integrating the Hamiltonian differential equations via a second order leapfrog discretization scheme. The inversion results suggest a high resistivity structure in the north-western part of the area, which correlates well with the presence of laterites. In the south-western part, a very high conductive zone is observed near the coast indicating an extensive influence of saltwater intrusion. Our results also show that the effect of intrusion of saline water diminishes from the south-western part to the north-eastern part of the region. Two dimensional modeling of four resistivity profiles shows that the groundwater flow is partly controlled by existing lineaments, fractures, and major joints. Groundwater occurs at a weathered/semi-weathered layer of laterite/clayey sand and the interface of overburden and crystalline basement. The presence of conduits is identified at a depth between 10 and 15 m along the Dhamapur–Kudal and Parule–Oros profiles, which seems to be potential zone for groundwater exploration. The NW–SE trending major lineaments and its criss-cross sections are indentified from the apparent and true resistivity surface map. The pseudo-section at different depths in the western part of the area, near Parule, shows extensive influence of saltwater intrusion and its impact reaching up to a depth of 50 m from the surface along the coastal area. Further, the deduced true electrical resistivity section against depth correlates well with available borehole lithology in the area. Present analyses suggest that HMC-based BNN method is robust for modeling resistivity data especially in hard rock terrains. These results are useful for interpreting fractures, major joints, and lineaments and crystalline basement rock and also for constraining the higher dimensional models. 相似文献
16.
Salinity mapping of coastal groundwater aquifers using hydrogeochemical and geophysical methods: a case study from north Kelantan,Malaysia 总被引：2，自引：0，他引：2
Integrated hydrogeochemical and geophysical methods were used to study the salinity of groundwater aquifers along the coastal
area of north Kelantan. For the hydrogeochemical investigation, analysis of major ion contents of the groundwater was conducted,
and other chemical parameters such as pH and total dissolved solids were also determined. For the geophysical study, both
geoelectrical resistivity soundings and reflection seismic surveys were conducted to determine the characteristics of the
subsurface and groundwater contained within the aquifers. The pH values range from 6.2 to 6.8, indicating that the groundwater
in the study area is slightly acidic. Low content of chloride suggests that the groundwater in the first aquifer is fresh,
with an average concentration of about 15.8 mg/l and high geoelectrical resistivity (>45 ohm m). On the other hand, the groundwater
in the second aquifer is brackish, with chloride concentration ranging from 500 mg/l to 3,600 mg/l and very low geoelectrical
resistivity (<45 ohm m) as well as high concentration of total dissolved solids (>1,000 mg/l). The groundwater in the third
aquifer is fresh, with chloride concentrations generally ranging from 2 mg/l to 210 mg/l and geoelectrical resistivity of
greater than 45 ohm m. Fresh and saltwater interface in the first aquifer is generally located directly in the area of the
coast, but, for the second aquifer, both hydrogeochemical and geoelectrical resistivity results indicate that the fresh water
and saltwater interface is located as far as 6 km from the beach. The considerable chloride ion content initially suggests
that the salinity of the groundwater in the second aquifer is probably caused by the intrusion of seawater. However, continuous
monitoring of the chloride content of the second aquifer indicated no significant changes with time, from which it can be
inferred that the salinity of the groundwater is not affected by seasonal seawater intrusion. Schoeller diagrams illustrate
that sulphate concentrations of the groundwater of the second aquifer are relatively low compared to those of the recent seawater.
Therefore, this result suggests that the brackish water in the second aquifer is probably from ancient seawater that was trapped
within the sediments for a long period of time, rather than due to direct seawater intrusion. 相似文献
17.
Assessment of seawater mixing in a coastal aquifer by high resolution electrical resistivity tomography 总被引：1，自引：0，他引：1
S. Sathish L. Elango Ph.D. R. Rajesh M.Sc. V. S. Sarma Ph.D. 《International Journal of Environmental Science and Technology》2011,8(3):483-492
Seawater intrusion is a major problem in urbanized coastal regions of India which is due to over exploitation of groundwater for various purposes. This study was carried out with the objective of assessing the zone of mixing between seawater and groundwater in the coastal aquifer in south of Chennai, Tamil Nadu, India using high resolution electrical resistivity tomography. High resolution electrical resistivity tomography was carried out in five profiles perpendicular to the sea using IRIS make SYSCAL Pro-96 system with 2.5 m or 5 m inter-electrode separation. The maximum length of the profile was 170 m which resulted in a depth of investigation of 28.7 m. The apparent resistivity measured in this area varies from 0.3 ohm-m to 30,000 ohm-m. The apparent resistivity of saturated zone decreases towards the sea, indicating the influence of seawater. This was also confirmed by measuring the electrical conductivity of groundwater, which gradually increases from 156 μS/cm to 3430 μS/cm towards the sea. Further, the concentration profiles of electrical conductivity, sodium, chloride and chloride / bicarbonate ratio are compared with the high resolution electrical resistivity tomography profile. The distance of influence of seawater is comparatively high in northern part than in southern part of the area. The high resolution electrical resistivity tomography was effectively used to determine the effect of seawater mixing with groundwater. 相似文献
18.
Geoelectrical and hydrogeochemical studies for delineating seawater intrusion in the outlet of Wadi Ham, UAE 总被引：2，自引：0，他引：2
M. Sherif A. El Mahmoudi H. Garamoon A. Kacimov S. Akram A. Ebraheem A. Shetty 《Environmental Geology》2006,49(4):536-551
The Quaternary aquifer of Wadi Ham, UAE has been overexploited during the last two decades to meet the increasing water demands.
As a result, the dynamic balance between freshwater and seawater has been disturbed and the quality of the groundwater has
deteriorated. In this paper, a 2D earth resistivity survey was conducted in Wadi Ham in the area between Fujairah and Kalba
to delineate the seawater intrusion. Existing monitoring wells were used to measure the horizontal and vertical variations
in water salinity and thus to improve the interpretation of earth resistivity imaging data. Results of vertical electrical
soundings and chemical analyses of collected water samples were used to obtain an empirical relationship between the inferred
earth resistivity and the amount of total dissolved solids. This relationship was used along with the true resistivity sections
resulting from the inversion of 2D resistivity data to identify three zones of water-bearing formation (fresh, brackish, and
salt-water zones). Along the four 2D resistivity profiles, the depth to the fresh-brackish interface exceeded 50 m at the
western part of the area and was in the order of 10 m or less in the eastern side near the shoreline. Depth to the brackish-saline
water interface reached about 70 m in the western side and was in the order of 20 m in the eastern side. The thickness of
the fresh water zone decreases considerably in the farming areas toward Kalba and thus the degree of seawater intrusion increases. 相似文献
19.
Rory D. Henderson Frederick D. Day-Lewis Elena Abarca Charles F. Harvey Hanan N. Karam Lanbo Liu John W. Lane Jr. 《Hydrogeology Journal》2010,18(1):173-185
Electrical resistivity imaging has been used in coastal settings to characterize fresh submarine groundwater discharge and the position of the freshwater/salt-water interface because of the relation of bulk electrical conductivity to pore-fluid conductivity, which in turn is a function of salinity. Interpretation of tomograms for hydrologic processes is complicated by inversion artifacts, uncertainty associated with survey geometry limitations, measurement errors, and choice of regularization method. Variation of seawater over tidal cycles poses unique challenges for inversion. The capabilities and limitations of resistivity imaging are presented for characterizing the distribution of freshwater and saltwater beneath a beach. The experimental results provide new insight into fresh submarine groundwater discharge at Waquoit Bay National Estuarine Research Reserve, East Falmouth, Massachusetts (USA). Tomograms from the experimental data indicate that fresh submarine groundwater discharge may shut down at high tide, whereas temperature data indicate that the discharge continues throughout the tidal cycle. Sensitivity analysis and synthetic modeling provide insight into resolving power in the presence of a time-varying saline water layer. In general, vertical electrodes and cross-hole measurements improve the inversion results regardless of the tidal level, whereas the resolution of surface arrays is more sensitive to time-varying saline water layer. 相似文献
20.
The hydrogeochemical characterization of groundwater helps to assess the trend of salinization and freshening of the groundwater. The present study was carried out to understand the lateral and vertical variation of groundwater salinity and the process of salinization and freshening of the groundwater in a coastal aquifer comprising a freshwater lens. The partially isolated unconfined aquifer selected for the present study is lying just south of the Chennai City, one of the densely populated cities on the east coast of South India. Critical problems affecting this aquifer include a thin aquifer which is connected/surrounded by saltwater on all the sides, overexploitation of the groundwater, surface impermeabilization due to increasing residential areas, and destruction of existing dune morphology by conversion of barren land to the residential area which causes a reduction in their barrier effect to seawater intrusion. The process of salinization and freshening of the groundwater was studied and monitored by using electrical resistivity survey and hydrogeochemical analysis. The vertical electrical sounding was carried out at 17 locations, and 400 water samples were collected and analyzed from 50 locations during the period from August 2008 to May 2010 for this study. The apparent resistivity values were analyzed and compared with groundwater quality to demarcate the zone of seawater intrusion. The regional flow direction of the groundwater is westward and eastward with respect to the central stretch and groundwater level ranges from 4.96 m MSL at the dune morphology to 0 m MSL along the boundary on all the sides. Base exchange index indicates that salinization trend in the northern part of the study area is due to the extensive groundwater pumping which increases the possibility of seawater intrusion. The increase of base exchange index towards southern part indicates a better groundwater quality of the aquifer due to proper land use practices. A strong trend of quality alteration is clearly visible from the base exchange index in response to the seasonal change between monsoon and dry season. In the western side, the monsoonal variation in the salinization and freshening of the groundwater was not noticed; however, the salinity is slightly higher than freshwater due to the presence of clay. 相似文献