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基于水化学的东海岛海水入侵时空变化特征 总被引：1，自引：0，他引：1
海水入侵对海岛海岸带地区地下淡水以及生态景观的变化存在重要影响,是该区域重要的灾害地质问题之一。海水入侵区域由于受到不同时段、地段地下淡水补给等可变因素影响,具有时空变化的特性。以东海岛东南部为主要研究靶区,利用三线图法对该区域2012年12月~2014年8月周期性监测数据进行研究分析,并以HCO_3~-和Cl~-为划分依据,构建海水入侵程度的划分标准,对不同时期的海水入侵情况做了研究。分析表明,监测期内东海岛经历了多次海水入侵-后退过程,入侵量分别为56.7%、51.1%、56.4%、42.7%、36.5%、76.9%、66.8%和75.8%,年际对比表明,东海岛海水入侵有日趋加重趋势。 相似文献
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莱州市是我国海水入侵的典型地区,为探明莱州市海水入侵灾害风险程度及灾害影响要素,本研究基于海水入侵灾害发生的链式传递过程,根据致灾因子危险性、承灾体易损性、灾害损失及防灾减灾能力构建了莱州市海岸带海水入侵灾害风险评价指标体系,基于最小信息熵将层次分析法(AHP)和熵权法(EWM)进行结合确定各指标权重,通过综合加权评价法得到海岸带各镇街风险总值并进行风险排名,并通过指标大小数值对比及皮尔逊相关性检验揭示各指标风险影响程度。结果表明：根据风险总值可将城港路街道、永安路街道及金城镇划分为海水入侵灾害高风险区,沙河镇、三山岛街道及虎头崖镇为较高风险区,土山镇及金仓街道为较低风险区,其中城港路街道风险最高,风险指数值为5.76,金仓街道风险最低,风险指数值为4.03;在各指标中,地下水开采强度与风险总值的相关系数达0.917,表明地下水开采强度是区域海水入侵风险评定的控制指标,该指标为防止海水入侵灾害的关键要素。 相似文献
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论海水入侵综合防治应用技术 总被引：9，自引：1，他引：9
本文概述了当前国内外控制海水入侵灾害的技术与方法,结合我国海水入侵实际情况,尤其是针对莱州湾地区海水入侵的特点,提出海水入侵综合防治应用技术与策略.海水入侵的防治是一个涉及从陆地到海洋,从地上到地下,从自然环境到人类社会经济发展的综合性问题.通过工程措施和调度手段,在海水入侵区实施流域洪水拦蓄补源、雨水资源化集流利用技术,营建地下帷幕阻成蓄淡工程,以及实行地表地下多种可利用水体联合供水优化调度,可有效防治海水入侵.从适应、改良、治理海水入侵区域不良环境入手,实施海水入侵区节水农业技术,调整产业结构,发展生态农业,是改善海水入侵区受害生态环境,缓解海水入侵灾害问题的重要宏观调控手段. 相似文献
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在总结前人关于海水入侵危险性评价研究的基础上,提出了基于GIS的层次分析法和模糊综合评判法,并以深圳市宝安区为例建立了海水入侵危险性评价体系.首先研究了宝安区海水入侵现状;然后选取了含水层结构、地下水氯离子质量浓度、地下水水位、地形地貌、与海岸线距离、地下水开采、土地利用类型7个评估因子;再利用层次分析法确定了各评估因子的权重,根据模糊综合评判法的原理,经过模糊运算得到危险性级别;最后运用GIS空间分析功能实现了海水入侵灾害危险性区划.结果表明:评价结果与该地区的海水入侵现状吻合较好.高危险区和较高危险区面积达107.77 km2,占研究区总面积的46.7%. 相似文献
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秦皇岛市海水入侵灾害评价及防治对策 总被引：2，自引：0，他引：2
自20世纪80年代初秦皇岛市沿海出现海水入侵以来,入侵面积逐年增加,已发展成为海岸带主要地质灾害之一。论文在海水入侵灾害勘查、监测成果的基础上,详细阐述了该区海水入侵现状、分布特征、演化过程和入侵方式。探讨了海水入侵的机理,指出人类活动是海水入侵的诱发因素,超采地下水是海水入侵的根本原因。应用基于GIS的层次分析法进行了危险性评价,从地学角度,提出了综合防治对策。 相似文献
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通过对大连大魏家、秦皇岛枣园和莱州湾南岸海水入侵的调查,结合已有研究成果和方法,笔者总结和梳理了环渤海地区海水入侵研究现状及存在的问题,并探讨了海水入侵调查研究技术方法。多年来对环渤海地区海水入侵的调查研究工作,基本查清了不同地段、不同类型海水入侵的机理和动态变化趋势,并为海水入侵有效防治提供了科学依据。随着海水入侵问题研究的深入,发现在水文地质条件、地下水动态监测及海水入侵对生态环境影响等方面仍存在问题,应持续加强海水入侵监测与研究。海水入侵调查研究是一项涉及多学科的综合性技术,应从基础调查,综合分析、动态监测和数值模拟等多方面开展研究。综合运用水化学分析、同位素示踪、室内模拟试验等技术方法,在充分揭示海水入侵机理和过渡带溶质运移规律的基础上,实现对海水入侵变化趋势的预测预报,提高对海水入侵的防范意识。 相似文献
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通过对硇洲岛海水入侵的地质条件、人为因素等研究分析,查明了海水入侵范围及危害现状,并对海水入侵内在因素及外部原因进行初步研究探讨。提出遏制硇洲岛海水入侵的对策措施,以期减少滨海地区发生海水入侵等环境地质问题。 相似文献
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大连大魏家水源地海水入侵过程中水文地球化学作用分析及定量模拟 总被引：1，自引：0，他引：1
大连大魏家水源地位于中国北方典型滨海岩溶地区。近年来,地下淡水不合理开采造成的地下水位降落漏斗引发了严重的海水入侵。本文以大魏家水源地海水入侵为研究对象,通过大量的水文地质调查和水化学样品测试分析,探讨了海水入侵形成的水动力条件,通过绘制Piper图、以Cl^-为天然示踪剂计算了海水和地下淡水的混合比例、实际浓度和理论浓度的对比、水化学组成特征分析等方法,探讨了该区岩溶含水层在海水入侵过程中所发生的主要水文地球化学作用,并对其进行了定量模拟,进而阐明了岩溶含水层中的海水入侵机理。研究结果表明,研究区微成水和成水并不是地下水淡水和海水简单混合而成。利用反向水文地球化学模拟揭示了控制滨海岩溶含水层中水化学演化的主要水文地球化学反应有方解石、蒙脱石和石膏的溶解作用,伊利石的沉淀作用以及Ca—Na离子交换作用,伴随着CO2的释放,石膏的溶解并没引起白云石化作用。 相似文献
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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
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To delineate spatial extent of seawater intrusion in a small experimental watershed in the coastal area of Byunsan, Korea,
electrical resistivity surveys with some evaluation core drillings and chemical analysis of groundwaters were conducted. The
vertical electrical sounding (VES) method was applied, which is useful to identify variations in electrical characteristics
of layered aquifers. The drilling logs identified a three-layered subsurface including reclamation soil, weathered layer and
relatively fresh sedimentary bedrock. The upper two layers are the main water-bearing units in this area. A total of 30 electrical
sounding curves corresponded mostly to the H type and they were further divided into three classes: highly conductive, intermediate,
and low conductive, according to the observed resistivity values of the most conductive weathered layer. In addition, groundwater
samples from 15 shallow monitoring wells were analyzed and thus grouped into two types based on HCO3/Cl and Ca/Na molar ratios with TDS levels, which differentiated groundwaters affected by seawater intrusion from those not
or less affected. According to relationships between the three classes of the sounding curves and groundwater chemistry, locations
of the monitoring wells with low HCO3/Cl and Ca/Na ionic ratios coincided with the area showing the highly conductive type curve, while those with the high ratios
corresponded to the area showing low conductive curve type. Both the low electrical resistivity and the low ionic ratios indicated
effects of seawater intrusion. From this study, it was demonstrated that the VES would be useful to delineate seawater intrusion
in coastal areas. 相似文献
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A. Antony Ravindran 《Russian Geology and Geophysics》2013,54(12):1529-1538
Groundwater is a very important component of water resources in coastal aquifers in Thoothukudi. It has been established that the groundwaters in the coastal zone of the Zirconium Complex, Pazhayakayal, Thoothukudi district, Tamilnadu, India, are subjected to wave and tidal impact. The groundwater quality was studied by hydrogeological methods, 2D electrical resistivity imaging (ERI) techniques (six profiles), 11 Wenner vertical electrical sounding (VES), and well log analysis. Also, nine geochemical water samples were taken from the study area. The 2D ERI and VES surveys were carried out using WGMD-4 Ltd., Chennai, resistivity meter, multicore cable, and multielectrodes with Wenner array. The collected resistivity data were interpreted using the Res2DINV software. The research shows that the groundwaters are the result of the paleoriver flow along the Tamirabarani Channel in the western area and of the seawater intrusion in the eastern area. The fresh water is characterized by resistivity of about 10–100 Ohm?m in the study area. The resistivity of 10–50 Ohm?m indicates that the subsurface section is made up of sand, clay, and caliche. Resistivity values of more than 200 Ohm?m are specific to sand dunes. The very low resistivity (<5 Ohm?m) layer might be due to the seawater intrusion in the study area. Six water samples from the well drilled in the coastal area were analyzed, which made it possible to determine the concentrations of major and trace elements in the groundwaters. These data were used to establish the seawater intrusion and coastal environment characteristics in the study area. 相似文献
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Md. Mizanur Rahman Sarker Marc Van Camp Mazeda Islam Nasir Ahmed Kristine Walraevens 《Environmental Earth Sciences》2018,77(2):39
In the coastal region of Bangladesh, groundwater is mainly used for domestic and agricultural purposes, but salinization of many groundwater resources limits its suitability for human consumption and practical application. This paper reports the results of a study that has mapped the salinity distribution in different aquifer layers up to a depth of 300 m in a region bordering the Bay of Bengal based on the main hydrochemistry and has investigated the origin of the salinity using Cl/Br ratios of the samples. The subsurface consists of a sequence of deltaic sediments with an alternation of more sandy and clayey sections in which several aquifer layers can be recognized. The main hydrochemistry shows different main water types in the different aquifers, indicating varying stages of freshening or salinization processes. The most freshwater, soft NaHCO3-type water with Cl concentrations mostly below 100 mg/l, is found in the deepest aquifer at 200–300 m below ground level (b.g.l.), in which the fresh/saltwater interface is pushed far to the south. Salinity is a main problem in the shallow aquifer systems, where Cl concentrations rise to nearly 8000 mg/l and the groundwater is mostly brackish NaCl water. Investigation of the Cl/Br ratios has shown that the source of the salinity in the deep aquifer is mixing with old connate seawater and that the saline waters in the more shallow aquifers do not originate from old connate water or direct seawater intrusion, but are derived from the dissolution of evaporite salts. These must have been formed in a tidal flat under influence of a strong seasonal precipitation pattern. Long dry seasons with high evaporation rates have evaporated seawater from inundated gullies and depressions, leading to salt precipitation, while subsequent heavy monsoon rains have dissolved the formed salts, and the solution has infiltrated in the subsoil, recharging groundwater. 相似文献
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Delineation of groundwater provenance in a coastal aquifer using statistical and isotopic methods,Southeast Tanzania 总被引：4，自引：3，他引：1
Said Suleiman Bakari Per Aagaard Rolf D. Vogt Fridtjov Ruden Ingar Johansen Said Ali Vuai 《Environmental Earth Sciences》2012,66(3):889-902
Rapid population growth and urbanization has placed a high demand on freshwater resources in southeast costal Tanzania. In this paper, we identify the various sources of groundwater and the major factors affecting the groundwater quality by means of multivariate statistical analyses, using chemical tracers and stable isotope signatures. The results from hierarchical cluster analyses show that the groundwater in the study area may be classified into four groups. A factor analysis indicates that groundwater composition is mainly affected by three processes, accounting for 80.6% of the total data variance: seawater intrusion, dilution of groundwater by recharge, and sewage infiltration. The hydrochemical facies of shallow groundwater was mostly of the Na–Ca–Cl type, although other water types were also observed. The deep groundwater samples were slightly to moderately mineralized and they were of the NaHCO3 type. This water type is induced mainly by dissolution of carbonate minerals and modified by ion exchange reactions. The signal from the stable isotope composition of the groundwater samples corresponded well with the major chemical characteristics. In the shallow groundwater, both high-nitrate and high-chloride concentrations were associated with localized stable isotope enrichments which offset the meteoric isotopic signature. This is inferred to be due to the contamination by influx of sewage, as well as intrusion by seawater. The depleted stable isotope values, which coincides with a chemical signature for the deep aquifer indicates that this deep groundwater is derived from infiltration in the recharge zone followed by slow lateral percolation. This study shows that a conceptual hydrogeochemical interpretation of the results from multivariate statistical analysis (using HCA and FA) on water chemistry, including isotopic data, provides a powerful tool for classifying the sources of groundwater and identifying the significant factors governing the groundwater quality. The derived knowledge generated by this study constitutes a conceptual framework for investigating groundwater characteristics. This is a prerequisite for developing a sound management plan, which is a requirement for ensuring a sustainable exploitation of the deep aquifer water resource in the coastal area of Tanzania. 相似文献
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Sang Yong Chung Venkatramanan Senapathi Selvam Sekar Tae Hyung Kim 《Hydrogeology Journal》2018,26(6):1875-1885
Monitoring and time-series analysis of the hydrological parameters electrical conductivity (EC), water pressure, precipitation and tide were carried out, to understand the characteristics of the parameter variations and their correlations at a coastal area in Busan, South Korea. The monitoring data were collected at a sharp interface between freshwater and saline water at the depth of 25 m below ground. Two well-logging profiles showed that seawater intrusion has largely expanded (progressed inland), and has greatly affected the groundwater quality in a coastal aquifer of tuffaceous sedimentary rock over a 9-year period. According to the time series analyses, the periodograms of the hydrological parameters present very similar trends to the power spectral densities (PSD) of the hydrological parameters. Autocorrelation functions (ACF) and partial autocorrelation functions (PACF) of the hydrological parameters were produced to evaluate their self-correlations. The ACFs of all hydrologic parameters showed very good correlation over the entire time lag, but the PACF revealed that the correlations were good only at time lag 1. Crosscorrelation functions (CCF) were used to evaluate the correlations between the hydrological parameters and the characteristics of seawater intrusion in the coastal aquifer system. The CCFs showed that EC had a close relationship with water pressure and precipitation rather than tide. The CCFs of water pressure with tide and precipitation were in inverse proportion, and the CCF of water pressure with precipitation was larger than that with tide. 相似文献
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段梅 《地质灾害与环境保护》2016,(1):108-112
通过对硇洲岛地质和水文地质条件的综合分析,建立了本研究区三维地下水数值模型,并获取了相关含水层参数。从而建立海水入侵数值模型,对硇洲岛在不同开采条件下的海水入侵趋势进行了模拟预测,结果表明,减少开采量能减缓硇洲岛海水入侵;在满足当地供水需求的前提下,减少浅层水开采量,在远离沿海区域的中部地区适当增加中层水开采量的开采方案优于现状开采条件下的方案。本研究也为减缓海水入侵提供了相关科学依据。 相似文献
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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