Use and availability of ground-water

Every man has to consume a certain quatity of water every day. This use constitutes the most basic need for water. In households water is also used for basic hygiene, washing, cleaning, and for the transport of sewage. Water is used in industry for cooling, generating electric power, for the production of a large variety of goods, and other purposes. The greatest demand for water results from irrigation. To satisfy these demands, an increasing quantity of ground-water is used. It is available at many places, where far extended subsurface reservoirs exist; it is better protected against pollution than surface water. But even though ground-water exists in many geological formations, which seem to be infinite, the availability is limited. The recharge of ground-water is dependent on the supply of atmospheric moisture. Especially in semiarid and arid zones this component of the hydrologic cycle determines the availability of ground-water. Besides natural conditions, technical and economic factors such as drilling of boreholes and the cost of pumping of ground-water have to be considered. Also political decisions can limit the availability of ground-water. If, for instance, wetlands are destroyed by drawdown of ground-water, nontechnical and non-economical aspects are involved. We face undesirable effects of ground-water pumping. Whether these effects are tolerable or intolerable depends on the decision-making processes on a political level.     

Fatty acids and sterols of particulate matter in a brackish and seasonally anoxic coastal salt pond

Particulate matter and interfacial sediment from a seasonally anoxic coastal salt pond were analyzed for fatty acids and sterols to examine variations in organic sources, and compositional changes across the oxic-anoxic interface in the water column and at the sediment-water interface. Fatty acid distributions in suspended particles varied seasonally and as a function of depth. Fatty acids of algal origin (e.g. 16:3, 16:4, 18:3, 18:4) were abundant in particles in oxic surface waters, but these labile components were depleted in particles from the anoxic zone which instead were enriched in bacterial fatty acids (e.g. 16:1Δ⁹, 18:1Δ¹¹, anteiso-C₁₅). Sterol distributionsvaried less than fatty acid distributions and particles throughout the water column reflected an upper water algal source with little in situ alteration. There was evidence for an in situ conversion of Δ⁵-stenols to 5(α)H-stanols in suspended particles in the anoxic zone. Sinking particles and the interfacial sediment were compositionally similar to each other, but different from suspended particles. These data reflect differences in particle source, transport and transformation processes occuring in the water column.     

The impact of tourism on coastal areas

The manifold influences of tourism on coastal areas are analysed from three different angles: (1) The development of seaside tourism including the changes of socio-economic and settlement patterns; (2) its cultural impact on the local population; (3) its environmental aspects. Point 1 is described with the help of a model showing four peripheries in space and time: (I) the North Sea and Baltic coasts since the 18th century; (II) Southern Europe during the 19th century; (III) the North African shores around 1950; (IV) the tropical oceans after 1965. Within every periphery, several phases (pioneer, domestic, international) can be distinguished according to the origin of tourists, the investment, the know-how etc. While the beginning of every phase is dominated from abroad, later-on national actors play an increasing role. This applies also to point 2, which refers mainly to developing countries. As for point 3, mass tourism may result detrimentally on water supply, sensitive coastal landscapes, socio-cultural identity etc. Among the questions to be raised are: How far are industrial societies responsible for any negative impacts of tourism, and what are the chances for, and a general consciousness on, a sustainable tourism development?     

广西典型近岸海域表层沉积物碎屑矿物分布及其物源意义

基于"我国重点海岸带滨海环境地质调查与评价"项目,分析了广西典型岸段20 m以浅的海域表层沉积物和地貌类型及其分布特征,并在此基础上探讨了碎屑矿物含量和种类的分布、变化以及组合.研究结果表明:研究区水动力较强,作用方式多样,有近30种碎屑矿物,其中主要有石英、长石、钛铁矿、云母、锆石、黄铁矿以及海绿石等,重矿物较为丰富;自全新世早期海侵以来,研究区先后进入了浅海海湾相沉积环境,但碎屑矿物种类与之前基本相似,其含量变化是由于气候和海平面的波动而致;研究区碎屑矿物在以沉积物和地貌类型为单位的各类地质单元中,其含量和种类均有所不同,尤以重矿物的变异性最为突出;各研究区重矿物组合可分为2~3个亚分区,均反映出与沉积环境关系密切.结果表明,研究区碎屑物质主要源于周缘陆区风化剥蚀、海岸侵蚀和河流输入,碎屑物质具有陆源性.     

Modelling the geoid and sea-surface topography in coastal areas

This paper looks at the relation between the time-averaged level of the sea surface and a gravimertic geoid, as determined in coastal areas. Measurements in local regions can now be accurate enough to demonstrate that the geoid and mean sea level are not even parallel to each other, let alone identical. The accuracy and pattern structure of surface gravity data in some shelf seas is comparable with those on land, so that a marine geoid can be derived from surface data without using satellite altimetry. The geodetic objective is then to combine the two to determine sea surface topography. In principle, gravimetric studies provide the absolute datum so that local oceanographic models on the shelf can be combined with sea surface topography models related to the global ocean circulation. In contrast, sea surface topography information near deep ocean coasts must come from external sources and satellite altimetry used to give the gravity data needed to offset the less good coverage by ship-borne gravimetry.Marine Bouguer anomalies enable two specific problems of gravity anomaly patterns near the continent ocean transition to be overcome. The necessary extension of Stokes' condensation reduction is developed and illustrated along a north-south profile from the Mediterranean across the Cote d'Azur. The effect on gravity of deep ocean water introduces a geoid correction in the form of a dipolar ridge whose amplitude at the shore is about 11 cm. In addition to geostrophic currents, a semi-quantitative model for the thermohaline effects on sea surface topography is discussed in relation to sea level differences between the Atlantic and Mediterranean.In considering appropriate algorithms for local geoid computation, Kirby's Iterative Fourier Combination routine for combining altimetry and surface gravity is extended to account for global sea surface topography. The impact of very fast spherical harmonic analysis algorithms is discussed and a simple physical model is given which explains the short coherence lengths found for the global gravity field. This necessary assumption for any local geoid computation was hitherto purely empirical.Finally, the use of land data such as tide gauges, ellipsoidal heights from GPS, and orthometric heights from first order levelling are reviewed as ways of corroborating geodetic estimates of sea surface topography and its relation to levelling datums. Successful examples are given from southern England.     

Geochemistry and the understanding of ground-water systems

Geochemistry has contributed significantly to the understanding of ground-water systems over the last 50 years. Historic advances include development of the hydrochemical facies concept, application of equilibrium theory, investigation of redox processes, and radiocarbon dating. Other hydrochemical concepts, tools, and techniques have helped elucidate mechanisms of flow and transport in ground-water systems, and have helped unlock an archive of paleoenvironmental information. Hydrochemical and isotopic information can be used to interpret the origin and mode of ground-water recharge, refine estimates of time scales of recharge and ground-water flow, decipher reactive processes, provide paleohydrological information, and calibrate ground-water flow models. Progress needs to be made in obtaining representative samples. Improvements are needed in the interpretation of the information obtained, and in the construction and interpretation of numerical models utilizing hydrochemical data. The best approach will ensure an optimized iterative process between field data collection and analysis, interpretation, and the application of forward, inverse, and statistical modeling tools. Advances are anticipated from microbiological investigations, the characterization of natural organics, isotopic fingerprinting, applications of dissolved gas measurements, and the fields of reaction kinetics and coupled processes. A thermodynamic perspective is offered that could facilitate the comparison and understanding of the multiple physical, chemical, and biological processes affecting ground-water systems.

---

Resumen La geoquímica ha contribuido significativamente al entendimiento de los sistemas de aguas subterráneas durante los últimos 50 años. Entre los avances históricos puede incluirse el desarrollo del concento de facies hidroquímicas, la aplicación de la teoría de equilibrio, investigación de los procesos oxidación-reducción, y datación con radiocarbono. Otros conceptos, herramientas y técnicas hidroquímicas han ayudado a esclarecer los mecanismos de flujo y transporte en sistemas de agua subterránea, y han ayudado a descifrar un archivo de información paleoambiental. Información hidroquímica e isotópica puede utilizarse para interpretar el origen y modo de recarga de agua subterránea, descifrar procesos reactivos, aportar información paleohidrológica, y calibrar modelos de flujo de agua subterránea. Necesita avanzarse en la obtención de muestras representativas. Se necesitan mejoras en la interpretación de la información obtenida y en la construcción e interpretación de modelos numéricos que utilizan datos hidroquímicos. El mejor enfoque asegurará un proceso iterativo optimizado entre toma y análisis de datos de campo, interpretación, y la aplicación de herramientas de modelizado estadísticas, directas, e inversas. Se anticipan avances a partir de investigaciones microbiológicas, la caracterización de orgánicos naturales, caracterización isotópica, aplicaciones de mediciones de gas disuelto, y los campos de cinética de reacción y procesos acoplados. Se ofrece una perspectiva termodinámica que podría facilitar la comparación y entendimiento de los múltiples procesos físicos, químicos, y biológicos que afectan sistemas de aguas subterráneas.

---

Résumé La géochimie a contribué de façon importante à la compréhension des systèmes deaux souterraines pendant les 50 dernières années. Les avancées ont portées sur le développement du concept des faciès hydrochimiques, sur lapplication de la théorie des équilibres, létude des processus doxydoréduction, et sur la datation au radiocarbone. Dautres concepts, outils et techniques, ont aidé à l élucidation des élucider les mécanismes découlement et de transport dans les systèmes deaux souterraines, et à la compréhension des archives informations paléo-environnementales. Les informations hydrochimiques et isotopiques peuvent être utilisées pour interpréter lorigine et le mode de recharge des eaux souterraines, affiner lestimation des temps de recharge et d écoulements, déchiffrer les processus de réaction, apporter une meilleure information paléohydrogéologique et calibrer les modèles découlement des eaux souterraines. Beaucoup de progrès ont besoin dêtre réalisés pour obtenir des échantillons représentatifs. Des améliorations sont nécessaires dans linterprétation des informations obtenues, et dans la construction et linterprétation de modèles numériques utilisant des données hydrochimiques. La meilleure approches arsurément un processus itératif optimisé entre la collection de données de terrain et lanalyse, linterprétation, et lapplication doutils de modélisation statistique, inverse et direct. Des avancées sont anticipées par les dans le demeine des études microbiologiques, dans la caractérisation des matières organiques naturelles, le marquage isotopique, les mesures de gaz dissous, les réactions cinétiques la compréhension des couplages. Une perspectives thermodynamique pourraient faciliter la comparaison et la compréhension des multiples processus physiques, chimiques et biologiques qui affectent les systèmes hydrogéologiques.

     

沿海地区地下水模拟优化管理模型

针对中国一些沿海地区地下水超采及由此带来的海水入侵问题,将地表水补给、抽水量及地下水位等相嵌在一起,建立了沿海地区地下水模拟优化管理模型。将人工鱼群算法和基于MODFLOW2000的变密度地下水流及溶质运移模型耦合起来,对沿海地区地下水模拟优化管理模型进行求解。以山东省威海市节水示范区为例,验证模型的有效性和可靠性。结果表明,10、11、12月份抽水量最大,以后至第2年5月份依次是减少的;从区域分布上看,在临海区域1号井处抽水量是3500～1120m3/月,在其它井处是6540～2920m3/月;与现行方案相比,增加总有效供水1990m3,地下水平均水位升高0.29m,海水入侵问题能够得到解决。计算结果合理可行,为沿海地区地下水资源的科学管理和持续利用提供可靠依据。     

Climatic prediction of the terrestrial and coastal areas of Iraq

Climatic data from four meteorological stations in Iraq (Mosul, Baghdad, Basra, and Rutba) were obtained. The recorded temperature data since 1960 till 2007 and rainfall and evaporation data since 1960 till 2008 and 1970 till 2008, respectively, were used and interpreted. This study showed an increase in temperature of about 5°C/47?years and an increase in evaporation rate with a decrease in the rainfall rate. Carbon dioxide in the atmosphere appears to be a factor controlling climate change. Basra climate, due to its location which is nearest to the Arabian Gulf, is expressed as a coastal climate and has a different behavior from Mosul, Baghdad, and Rutba, which are considered as terrestrial climates.     

河口海岸铁板砂研究进展

铁板砂是一种特殊的沉积地貌,其性质和形成演化涉及海洋沉积动力、海洋工程地质等学科方向,对海岸防护、航运安全和海洋工程建设有重要影响。介绍了铁板砂的概念、特征和分布,以铁板砂形成和演化机制为主线,从原生沉积、冲刷分选和液化渗流3种模式出发,对国内外铁板砂研究现状进行总结和论述,分析了3种模式的优缺点和适用条件,从研究思路和研究方法等方面对铁板砂的研究趋势进行了展望,指出基于海洋土力学与沉积动力学相结合的思路,开展水体-床面-床内耦合的多要素同步观测,构建机制清晰的物理模型和定量评价的数学模型是今后铁板砂研究的发展方向。     

Inhibition of the decomposition ofZostera capricornii litter by macrobenthos and meiobenthos in a brackish coastal lake system

As part of the development of rapid assays to measure ecological processes, rates of decomposition of eelgrass,Zostera capricornii, were measured using litter bags placed at different distances from the sea in a coastal lake system. Average loss of dry mass over 28 d in bags with coarse mesh, which excluded animals >1.5 mm, varied from 364 to 448 mg in late winter to between 644 and 868 mg in autumn, depending on locality. Rates of loss were significantly greater in bags with small mesh (0.063 mm), from which all macrofauna were excluded, varying from 420 to 532 mg and from 868 to 924 mg in winter and autumn, respectively. There were consistent negative correlations between loss of litter and numbers of macrofauna and meiofauna in the bags. Rates of decrease in the organic fraction of the litter were positively correlated with numbers of animals. The results imply that the fauna inhibited decomposition, possibly by reducing microbial populations through grazing.     

A geospatial framework to estimate depth of scour under buildings due to storm surge in coastal areas

Hurricanes and tropical storms represent one of the major hazards in coastal communities. Storm surge generated by strong winds and low pressure from these systems have the potential to bring extensive flooding in coastal areas. In many cases, the damage caused by the storm surge may exceed the damage from the wind resulting in the total collapse of buildings. Therefore, in coastal areas, one of the sources for major structural damage could be due to scour, where the soil below the building that serves as the foundation is swept away by the movement of the water. The existing methodologies to forecast hurricane flood damage do not differentiate between the different damage mechanisms (e.g., inundation vs. scour). Currently, there are no tools available that predominantly focus on forecasting scour-related damage for buildings. Such a tool could provide significant advantages for planning and/or preparing emergency responses. Therefore, the focus of this study was to develop a methodology to predict possible scour depth due to hurricane storm surges using an automated ArcGIS tool that incorporates the expected hurricane conditions (flow depth, velocity, and flood duration), site-specific building information, and the associated soil types for the foundation. A case study from Monmouth County (NJ), where the scour damages from 2012 Hurricane Sandy were recorded after the storm, was used to evaluate the accuracy of the developed forecasting tool and to relate the scour depth to potential scour damage. The results indicate that the developed tool provides relatively consistent results with the field observations.     

Formation of the chemical composition of brackish and brine groundwater in the Tuva depression and surrounding areas

Groundwater with high salinity is widespread in different climatic and geologic environments of the world. The formation of its chemical composition, however, is still debatable. The chemical composition of groundwater has been studied in 19 springs of the Tuva depression. In this area, hydrocarbonate, sulfate, and chloride waters with different cation compositions discharge. Their TDS value varies mainly from 1 to 6 g/L, reaching 315 g/L at only one locality. The chemical composition of the studied waters is reflective of the geostructural, hydrogeologic, landscape, and geochemical conditions. The main processes determining the chemical composition of the waters are their interaction with aluminosilicate minerals, dissolution of gypsum and halite, evaporation, and oxidation of sulfide minerals.     

Grain‐size distributions and coastal morphodynamics along the southern Maryland and Virginia barrier islands

This study examined grain‐size distributions to address questions regarding geological and oceanographic controls on island morphodynamics along one of the longest undeveloped, mixed‐energy barrier island systems in the world. In particular, statistical analyses (i.e. analysis of variance, Tukey honest significant difference multiple comparison tests, nonparametric statistics and linear regression analysis) of 230 barrier island samples from Ocean City Inlet, Maryland, to the mouth of the Chesapeake Bay and 134 nearshore samples (d ≤ 10 m) identified grain‐size trends related to the morphodynamic characteristics of these systems. In general, the Virginia barrier islands north of Wachapreague Inlet and Assateague Island form a statistically different subset of grain sizes (medium‐grained to coarse‐grained sand) from the islands south of Wachapreague Inlet (fine‐grained sand). These textural trends corroborate the Pleistocene headlands of the Delmarva coastal compartment as the sediment source and indicate that some of the coarse‐grained to medium‐grained sediment bypasses the large sinks in the net southward longshore sediment transport system (i.e. Fishing Point and Chincoteague Inlet). This research also demonstrates that the preferential accumulation of coarse‐grained to medium‐grained sand on the ebb‐tidal delta at Wachapreague Inlet probably controls the erosional morphodynamics of the islands located downdrift (south) of the inlet. These results suggest that an increase in tidal prism, set up by sea‐level rise and/or a shift in wave climate/refraction patterns, may lead to barrier island fragmentation and a runaway transgression of this predominantly natural barrier island system. Consequently, a grain analysis of major coastal compartments, across multiple driving forces, can be used to assess coastal morphodynamics and the potential impact of climate change on coastal systems.     

中国沿海地区地面沉降问题思考

中国沿海地区地面沉降主要发生在大河三角洲及沿海平原区。文章主要以我国两大沿海城市——上海及天津为例，分析和阐述了沿海地区发生地面沉降的机理以及影响地面沉降发生发展的诸多因素。指出，孔隙水承压含水层中抽取地下水将引起承压水位降低进而引起土颗粒承担的有效压力的增大，从而使土层压缩。影响沿海地区地面沉降的因素有新构造运动、全球海平面上升、软土地基自然沉降、过量抽取地下流体以及建筑施工造成的局部沉降等。文章认为，在诸多影响因素中，人类过量开采地下流体是导致地面沉降发生的主要原因，人类应在资源利用和环境保护方面力争双赢。     

Created versus natural coastal islands: Atlantic waterbird populations, habitat choices, and management implications

Nesting colonial waterbirds along the Atlantic Coast of the United States face a number of landscape-level threats including human disturbance, mammalian predator expansion, and habitat alteration. There have been changes from 1977 to the mid-1990s in use of nesting habitats and populations of a number of seabird species of concern in the region, including black skimmersRynchops niger Linnaeaus, common ternsSterna hirundo Linnaeaus, gull-billed ternsSterna nilotica Linnaeaus, least ternsSterna antillarum Lesson, royal ternsSterna maxima Boddaert, and sandwich ternsSterna sandvicensis Cabot. These species form colonies primarily on the following habitat types: large, sandy barrier or shoal islands, natural estuarine or bay islands (mostly marsh) man-made islands of dredged deposition materials (from navigation channels), and the mainland. Significant changes in the use of the dredged material islands have occurred for these species in New Jersey and North Carolina, but not in Virginia. Population declines and changes in bird habitat use appear to be at least partially associated with the conditions and management of the existing dredged material islands, coastal policy changes associated with creating new dredged material islands, and competing demands for sand for beach augmentation by coastal communities. As these and other coastal habitats become less suitable for colonial waterbirds, other man-made sites, such as, bridges and buildings have become increasingly more important. In regions with intense recreational demands, coastal wildlife managers need to take a more aggressive role in managing natural and man-made habitats areas and as stakeholders in the decision-making process involving dredged materials and beach sand allocation.     

滨海咸水储层微纳米颗粒形貌特征对其运移行为的影响

通过一维水平砂柱试验,结合多孔介质传质理论,从孔隙尺度探索含水层中微纳米颗粒形貌特征与其释放、运移、沉积过程的内在关联,揭示颗粒重组的力学诱导机制。研究结果表明,在渗流溶液水动力作用与物化性质相同,并且含水介质机械组成相近的条件下,球形硅微粉释放率最高,试验过程中累计释放颗粒质量达93.74 mg;咸水层原砂释放率最低,仅为0.62%。依据试验结果,利用双沉积位动力学模型进行反演,计算得到咸水层原砂在受运移距离控制点位沉积系数最大,高于人工制备砂样2个量级。结合电镜扫描与颗粒表面ζ电位测试结果,基于颗粒受力平衡分析,渗流剪切应力与颗粒法向截面面积成正比;同时伴随微纳米颗粒形貌、构成的变化,扩散双电层排斥力存在显著差异。因此,球状硅微粉颗粒通常以单体形式脱离多孔介质表面;片状次生黏土矿物颗粒多以大体积粒团形式释放,出现再次沉积或被孔喉捕获的机率提高。     

Sustainable groundwater extraction in coastal areas: a Belgian example

Water extractions in coastal areas have to deal with salt water intrusion and lowering of hydraulic heads in valuable ecosystems. Therefore, sustainable management of fresh water resources in these areas is crucial. This is illustrated here with two water extractions in the western Belgian coastal plain which extract groundwater from a phreatic dune aquifer. One water extraction faced problems with salt water intrusion, while lowering of hydraulic heads was an issue for both. To remedy the salt water intrusion, it was found that decreasing the extraction rate was the only solution. To offset this and to increase hydraulic heads around both extractions, it was decided to artificially recharge the aquifer of the second extraction with tertiary treated wastewater. By taking these interventions, the combined production capacity of the water extractions was increased with 56% whereas 27% less water was extracted from the dune aquifer itself. Extraction history and the effects of interventions are illustrated for both water extractions with water quality data and fresh water head observations. A more detailed insight in groundwater flow and fresh–salt water distribution in the aquifer is provided by simulating the evolution of the water extractions with a 3D density dependent groundwater flow model.     

中国沿海及内陆地区长周期脉动特征分析

地脉动台阵观测作为一种低成本的剪切波速度构造探测方法,预计将在中国地震灾害预防中起到重要作用。为了研究地脉动台阵观测中长周期信号的特征以及中国长周期地脉动的特点和适用性,开展了中国从沿海到内陆地区地脉动信号的观测和分析,探查由沿海到内陆地区地脉动的变化规律以及内陆地区广域的地脉动特征,发展适合于我国内陆地区的基于地脉动的地下构造勘探方法,在中国大陆上海市、西安市、天水市及兰州市进行了长周期地脉动观测。现场试验结果表明,上海地脉动特征与日本关东平原地区的观测结果类似,可以认为在海岸地区深部结构调查的地脉动台阵观测有良好的适用性。然而,西安、兰州、天水长周期地脉动能量只有上海的千分之一,因此需要进一步研究更加灵敏的仪器性能和更加稳定的观测方法。