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1.
基岩岛屿占我国岛屿的90%以上,且岛屿上的淡水资源十分珍贵。目前,岛屿上的供水(船运、雨水收集、海水淡化等)存在成本高、设备易坏等缺点。因此,岛屿的地下水资源无疑是优质、可靠、稳定的供水源。为了更好地开发基岩岛屿地下水资源,认为针对基岩岛屿地下水模拟,从地下水理论、地下水模拟的国内外研究现状和模拟模型等方面进行了综述。总结认为: 基岩岛屿的地下水多以“淡水蘑菇体”的形式储存,有别于沙质岛屿; 模拟模型应概化为横向各项同性的达西流或非达西流,或二者的耦合模型,并归纳了相应的地下水流运动方程; 基岩岛屿地下水模拟模型应分为孔隙型、裂隙型和孔隙-裂隙型3种类型; 在岛屿边界设定上,基岩海岸应设为隔水边界,沙质海岸应设为定水头边界。综述研究认为: 基岩岛屿地下水模拟模型应尽可能精细、完整、精准地刻画基岩岛屿的地质地貌,设置完整的岛屿补径排项; 模拟时,应准确对应基岩岛屿的地下水类型,选准模拟方法与模拟软件; 模型验证工作也是十分重要,需多次与岛屿水量均衡,且与实测水量和水位作对照,不断地修善模型。以上综述成果为我国今后开展基岩岛屿地下水数据模拟提供了理论依据。 相似文献
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基岩岛屿占我国岛屿的90%以上,且岛屿上的淡水资源十分珍贵。目前,岛屿上的供水(船运、雨水收集、海水淡化等)存在成本高、设备易坏等缺点。因此,岛屿的地下水资源无疑是优质、可靠、稳定的供水源。为了更好地开发基岩岛屿地下水资源,认为针对基岩岛屿地下水模拟,从地下水理论、地下水模拟的国内外研究现状和模拟模型等方面进行了综述。总结认为:基岩岛屿的地下水多以"淡水蘑菇体"的形式储存,有别于沙质岛屿;模拟模型应概化为横向各项同性的达西流或非达西流,或二者的耦合模型,并归纳了相应的地下水流运动方程;基岩岛屿地下水模拟模型应分为孔隙型、裂隙型和孔隙-裂隙型3种类型;在岛屿边界设定上,基岩海岸应设为隔水边界,沙质海岸应设为定水头边界。综述研究认为:基岩岛屿地下水模拟模型应尽可能精细、完整、精准地刻画基岩岛屿的地质地貌,设置完整的岛屿补径排项;模拟时,应准确对应基岩岛屿的地下水类型,选准模拟方法与模拟软件;模型验证工作也是十分重要,需多次与岛屿水量均衡,且与实测水量和水位作对照,不断地修善模型。以上综述成果为我国今后开展基岩岛屿地下水数据模拟提供了理论依据。 相似文献
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岛屿是我国领土的重要组成部分,对国家安全和国防军事意义非凡。岛屿的地下水资源尤为珍贵,地下水流场模拟是研究地下水分布规律的重要手段。水文地质条件复杂、可利用的观测井较少等原因,造成了基岩岛屿水文地质模型概化精度不高、初始条件难以获取等问题。为克服基岩岛屿地下水流场模拟的诸多困难,将珠海外伶仃岛作为研究区,利用数字高程模型数据开展地质地貌建模; 利用探地雷达法、直流电法与地质分析对岛屿进行探测,获取了地层数据; 采用地下水遥感评估法,利用实测井位数据,确定了地下水的初始水位,进而对基岩岛屿地下水流场进行建模; 最终,通过对外伶仃岛地下水流场的数值模拟得出地下水模拟流场图。岛上多个测点的探测水位值与模拟水位相关性较好,其拟合优度R2为0.872 2。由此可见,综合遥感、物探、水文地质手段等技术方法获取的数据,采用地下水模拟软件或程序实现基岩岛屿地下水流场的数值模拟,是基岩岛屿地下水资源研究的一个有效方法。 相似文献
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以青海省平安县洪水泉乡地下水勘查为例,对该区域地下水赋存条件及分布规律、含水岩组划分及富水性、地下水补给、径流与排泄条件、地下水水化学特征进行研究,将区内地下水类型划分为第四系松散岩类孔隙水、碎屑岩类孔隙裂隙水、碳酸岩夹碎屑岩裂隙溶隙水、基岩裂隙水和冻结层水五大类,富水性分级与区域地下水一致。根据区内水文地质条件,离基岩山区近的村庄可以采用引泉方式解决供水,而远离基岩山区的低山丘陵村庄人畜饮水集中供水水源可采用大口井廊道取水工程来解决。通过合理开发利用地下水来解决当地供水需求。 相似文献
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本文讨论了孔隙-裂隙含水层地下水向水井流动特性。假定条件是孔隙、裂隙发育均匀、岩石骨架刚性等。通过1960年巴连勃拉特建立的孔隙-裂隙双重介质模型,分别对孔隙、裂隙导出了普遍适用的承压含水层地下水渗流基本微分方程。 与裂隙中水的渗流速度相比,孔隙中水的渗流速度很小,可以忽略,并借助达西定律、状态方程等辅助方程,对无越流、无限含水层轴对称问题,用拉普拉斯变换方 相似文献
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基于碳酸盐岩储集层成岩作用中受孔隙尺寸控制的矿物沉淀和胶结非均质特征的发现与思考,结合当今国内外有关多孔介质中流体—岩石相互作用及化学流体动力学研究进展的调研,对相关研究进展及其地质意义进行了简单的梳理和归纳。(1)地质环境中“孔隙尺寸控制沉淀”现象广泛存在,表现为储集层孔隙的胶结非均质性及其最终形成的“大孔充填而小孔保存”特征。现今研究主要从不同尺度孔隙结构观察、流体—孔隙介质相互作用的数值模拟、矿物沉淀实验3个方面开展。(2)受孔隙尺寸控制的非均质沉淀特征可以利用与表面化学相关的动力学模型进行解释,即微孔隙中更大的界面张力和矿物晶体曲率导致矿物的有效溶解度更高,因而更容易保持过饱和状态而不发生沉淀。(3)“孔隙尺寸控制沉淀”现象可使油气储集层发生微孔的选择性保存,在不同尺度孔隙共生的情况下,较大孔隙更倾向于被胶结充填而小孔则更易于被保存,不同的胶结模式对岩石整体渗透率的影响略有不同;该现象在地热储集层开发和二氧化碳地质封存研究中也值得重视。最后,结合鄂尔多斯盆地马家沟组碳酸盐岩储集层的非均质胶结特征和孔隙分布,分析总结成岩流体性质、来源及胶结模式差异对孔隙结构演化和优质储集层分布的影响。“孔隙尺寸控制沉淀”现象的发现和重视对于理解流体—岩石复杂作用过程具有重要理论意义,也为储集层成岩作用和孔隙保存研究提供了新的视点和思考角度。 相似文献
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广州市花都区地下水资源较丰富,根据地下水的赋存条件,地下水类型划分为松散岩类孔隙水、碳酸盐岩裂隙岩溶水、红层孔隙裂隙水、层状岩类裂隙水及块状岩类裂隙水。其中供水意义较大的地下水类型为松散岩类孔隙水和碳酸盐岩裂隙溶洞水。依据应急水源地圈定依据,圈定四处地下水应急水源地,对潜在供水能力、水质及地下水开采风险进行评价。结果显示:各应急水源地地下水水质总体良好,经相应处理后可满足应急供水水质需求,地地下水开采风险主要有地质灾害风险、地下水污染风险及开采技术风险。应急状态下,各水源地地下水总允许开采资源为72 119.13 m^3/d,可满足花都区63.86%常住人口的应急供水。 相似文献
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我国城市海岸带地下水类型和分布主要受控于陆地地质作用,尤以大地构造作用和河流地质作用为主导。松散沉积物类海岸带地下水为孔隙水,含水介质单一,空间变化大,地下水的赋存和分布规律亦相应复杂。以距今78万年晚更新世为界线,可将第四纪松散沉积物含水层组划分为上（浅）下（深）两层（部）。下部的全新统（Q4）和上更新统（Q3）含水岩组以微咸水、咸水多见;上部的中更新统（Q2）和下更新统（Q1）分布有淡水,部分地下淡水资源有一定的供水意义。基岩类海岸带地下水主要为裂隙水和岩溶水,多为淡水,其水资源量与当地的降水量和基岩入渗系数的大小有直接关系。除砂砾石台地的基岩类海岸带、少数溺谷型泥质海岸带的河谷内和碳酸盐岩分布区外,一般无集中供水意义。 相似文献
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淡水透镜体作为海岛上珍贵的地下淡水资源,对于满足居民生活用水与维护生态系统具有重要作用,增加海岛地下淡水资源储量可有效缓解海岛地区普遍存在的水资源短缺问题。本研究提出通过在海岛外部区域采用低渗透性介质材料增加海岛地下淡水资源储量的方法,采用室内物理模型实验与基于变密度地下水流溶质运移模型的数值模拟相结合的方法对提出方法的有效性进行了验证,并通过野外尺度的数学模型分析工程实施可能性。实验与数值模拟结果较吻合,表明该方法具有抵御海水入侵、增加海岛地下淡水资源储量的巨大潜力。通过基于野外尺度的数值模拟分析工程实施的可能性,发现对于降雨入渗补给强度为0.005 7 m/d、长度为200 m,孔隙度为0.3的狭长形均质海岛,地下淡水储量为66.5 m3/m,在海岛外部区域采用渗透系数为1 m/d、厚度为5 m的低渗透性介质材料后,淡水透镜体经过约8 a时间可再次达到稳态,地下淡水储量为343.8 m3/m,增加约4倍,工程实施具备一定可能性。本研究为缓解海岛地区缺水问题、实现淡水资源可持续利用提供了一种新方法。 相似文献
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Groundwater in a coral island 总被引：4，自引：3，他引：1
Freshwater aquifers in small coral islands usually occur as thin lenses which are significantly influenced by stresses such
as groundwater pumping, sea tides, etc. Kavaratti, a coral island, is one of the 36 such islands in the Arabian Sea off the
western coast of India. Detailed hydrogeological investigations were carried out to determine the quantity of freshwater that
could be pumped in addition to the present usage. Salinity of groundwater must remain within permissible limits and a 2-D
solute mass transport model with a vertical section of the island was constructed by the computer code SUTRA. The model was
calibrated by obtaining a match of computed and observed values of the water table, tidal efficiency, and salinity of groundwater
at the water table. The model analysis showed that the salinity of groundwater continues to increase unless groundwater pumping
is kept below a certain rate. Groundwater potential can be augmented by reducing the subsurface outflow to the sea and by
raising the water table by a subsurface dam.
Received: 8 September 1997 · Accepted: 27 April 1998 相似文献
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Conceptual hydrogeological model of volcanic Easter Island (Chile) after chemical and isotopic surveys 总被引：2，自引：2，他引：0
Most human activities and hydrogeological information on small young volcanic islands are near the coastal area. There are almost no hydrological data from inland areas, where permanent springs and/or boreholes may be rare or nonexistent. A major concern is the excessive salinity of near-the-coast wells. Obtaining a conceptual hydrogeological model is crucial for groundwater resources development and management. Surveys of water seepages and rain for chemical and environmental isotope contents may provide information on the whole island groundwater flow conditions, in spite of remaining geological and hydrogeological uncertainties. New data from Easter Island (Isla de Pascua), in the Pacific Ocean, are considered. Whether Easter Island has a central low permeability volcanic “core” sustaining an elevated water table remains unknown. Average recharge is estimated at 300–400 mm/year, with a low salinity of 15–50 mg/L Cl. There is an apron of highly permeable volcanics that extends to the coast. The salinity of near-the-coast wells, >1,000 mg/L Cl, is marine in origin. This is the result of a thick mixing zone of island groundwater and encroached seawater, locally enhanced by upconings below pumping wells. This conceptual model explains what is observed, in the absence of inland boreholes and springs. 相似文献
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This paper focuses on a small back-barrier sand-island on the southeast coast of Queensland. The freshwater lens in the study area exhibits anomalously high short-range salinity gradients at shallow depths, which cannot be explained using a standard seawater intrusion model. The island groundwater system consists of two aquifers: a semiconfined aquifer hosting saline to hypersaline groundwater and an overlying unconfined freshwater aquifer. The deeper aquifer is semiconfined within an incised paleovalley, and groundwater flow is restricted to an east – west direction. Tidal response observations show that the tidal signal propagates far more rapidly and is of much higher magnitude in the semiconfined aquifer than the unconfined aquifer. The tidal wave-pulse amplitude is also subject to greater attenuation in the unconfined aquifer. A conceptual hydrogeological model illustrates how upwelling of hypersaline groundwater, induced by density-dependent flow and tidal pumping, has contaminated the shallow groundwater resource. Salinisation at shallow depths is restricted to an area proximal to the paleovalley aquifer. The spatial distribution of lithological heterogeneity is an initial limiting control on the movement of the upwelling saline plume. The extent of shallow groundwater contamination is also limited by the presence of a baroclinic field, resulting from lateral variations in fluid density. Hydrochemical signatures have been used to support the model hypothesis and link the salinisation of fresh groundwater with the semiconfined aquifer as opposed to the surrounding estuarine surface water. The geometry and thickness of the freshwater lens are further controlled by the presence of the largely impermeable bedrock paleosurface between 9 and 12 m depth. The combination of hypersaline groundwater and hydraulically restrictive lithology at shallow depths has produced excessive thinning of the freshwater lens, demonstrating that the application of a model such as the Dupuit – Ghyben – Herzberg relationship would grossly overestimate the available groundwater resource. 相似文献
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Jeju Island is a volcanic island composed predominantly of permeable basalts. The island is poor in surface water but abundant in groundwater. No actual perennial streams exist and the water resources on the island are dependent almost entirely on groundwater. The groundwater bodies on the island are classified into three general categories: high level, basal and parabasal groundwaters. The parabasal groundwater is further subdivided into lower and upper parabasal groundwaters due to the position of the Seogwipo Formation, which is made up of sedimentary rocks with a low permeability. The distribution of each groundwater type was evaluated through analyses of the spatial distribution of the Seogwipo Formation and the hydraulic gradient of the groundwater. Basal groundwater emerges extensively along the coast of the eastern sector, less commonly along the coast of the western sector. Parabasal groundwater occurs extensively over most of the island except for the southern sector, where it occurs only locally in the coastal area. This paper presents a summary of several studies on the occurrence and features of groundwater resources on Jeju Island, the largest island in Korea. 相似文献
17.
N. C. Mondal V. S. Singh D. V. Sarwade M. V. Nandakumar 《Journal of Earth System Science》2009,118(3):217-229
A group of 36 coral islands is being scattered in the Arabian Sea off the western coast of India. On such islands, groundwater
is the only source of fresh water for the islanders. The demand for groundwater is increasing every year due to growing population
and urbanization. On the other side the peculiar hydrologic, geologic and geomorphic features restrict the availability of
groundwater. Thus a proper understanding of the groundwater condition is important in order to meet this increasing demand
and also to formulate future development and management strategies. Detailed hydrogeological, geophysical and hydrochemical
studies had been carried out to identify potential fresh groundwater resources and quantify vulnerable parts of Andrott Island,
Union Territory of Lakshadweep. Systematic collection and analysis of hydrological, geophysical and hydrochemical data gives
an early signal of deterioration in groundwater quality in the peripheral parts of eastern and western coasts of this island
and it suggests immediate measures for arresting the deterioration in groundwater quality as well as augmentation for restoration
of aquifer in some parts of the island. 相似文献
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The island of Korčula, which has an area of 271.47 km2 is located along the north-eastern coast of the Adriatic Sea. Due to the Mediterranean climate, size and karst geology its
water resources are very scarce. This paper describes the natural features of the island (air temperature, precipitation,
geology, hydrogeology and groundwater) which are important for the water appearance and its distribution in time and space.
The water supply of the island has been managed in the following ways: through a pipeline from the mainland, by drawing groundwater
and by rain harvesting. Tourism causes high seasonal water needs which are barely met by the existing water supply system.
Therefore, present water resource management on the island must be improved. The paper also presents mathematical programming
scheme to get optimal costs and benefits of water exploitation on the island. Besides economic aspect, linear programming
is applied to social and ecological objectives, as well. This study suggests that island’s water management should be primarily
based on wisely using its proper water resources. 相似文献