陇东白垩系自流水盆地演化的水文地质意义

陇东盆地位于鄂尔多斯盆地西南部,形成于白垩世,受后期构造影响,由原生的封闭盆地变成了现今开放的自流水盆地含水系统。根据含水层的时空分布特征,可将陇东盆地分为第四系含水系统和白垩系含水系统两大系统;根据含水介质特征,在平面上可将陇东盆地地下水划分为白垩系碎屑岩类裂隙水、黄土孔隙裂隙水、河谷松散岩类孔隙水三大类型,垂向上黄土、河谷含水系统与白垩系含水系统不同含水岩组在空间上相叠置,其中黄土塬潜水、河谷潜水和白垩系深层承压水是具有供水意义的含水子系统。黄土塬潜水是独立的含水系统,白垩系深层承压水-潜水和河谷潜水形成了河流-盆地循环系统。盆地深层承压水径流缓慢,因此存在的深层淡水资源十分宝贵,可能属于不可再生的。     

焉耆盆地绿洲区承压水硝态氮含量空间变异研究

基于GIS与地统计学原理,使用Arc GIS地统计分析模块研究焉耆盆地绿洲区承压水硝态氮的空间变异情况。结果表明:灌溉水硝态氮数据服从对数正态分布,块金效应值为1.16,变程为0.198 km,空间相关性较弱;饮用水硝态氮数据服从对数正态分布,块金值为0.26,变程达1.58 km,空间相关性较强;承压水硝态氮数据同样服从对数正态分布,块金效应为0.53,变程为0.138 km,空间相关性中等;采用克里格插值方法绘制了承压水硝态氮含量分布图,可更直观地了解研究区地下水硝态氮分布。     

新疆阿图什哈拉峻地区地下水系统模型研究

根据阿图什哈拉峻地区地下水系统水文地质特征，采用系统分解合成方法，在单一的潜水、承压水地下水模型子系统基础上，建立了冲洪积扇地区地下水数学模型。用有限元方法对模型进行数值离散，利用Develop Studio软件编制计算程序，对边界条件及垂向水交换量进行动态模拟，对潜水和承压水稳定流静态流场、非稳定流动态流场进行了拟合，得到了该地区地下水系统水文地质参数，参数分布与水文地质勘察所得含水层结构特点及富水区分布基本相符。     

基于Visual MODFLOW的汉中盆地三维可视化模型构建方法

根据区域水文地质特征将地下水类型划分为潜水和承压水,概化含水层结构为包气带层、潜水含水层、弱透水层和承压含水层。综合利用钻孔、遥感影像、地质地貌、数字高程数据等资料,利用Visual MODFLOW软件中空间三维、非均质、各向异性的非稳定地下水流系统模型实现三维可视化。结果表明,该模型构建方法能够较为准确地刻画地层结构和水文地质特征,实现三维地质体的精准模拟,为进一步开展地下水数值模拟和溶质运移工作提供支撑。     

水文地质参数确定与地下水资源量计算方法分析

水文地质参数主要包括含水层的渗透系数、潜水含水层的给水度、降水入渗补给系数、灌溉入渗补给系数等。地下水资源量的计算是通过确定水文地质参数之后,选取地下水资源量的计算方法。文章分析确定了阜蒙县节水增粮工程项目区的水文地质参数,并阐述了地下水资源量的计算方法。     

潜水-微承压含水层水文地质参数求解方法研究

潜水-微承压含水层水文地质参数是正确评价山西临汾涝洰河生态建设工程,确定水库渗漏量的重要依据。以涝河河谷中段C6典型抽水试验为基础,基于含水层试验(Aquifer Test)专业软件,分析多种方法下获取的潜水-微承压含水层水文地质参数。结果表明,考虑潜水重力释水的Boulton法和水位恢复法求得的水文地质参数稳定可靠,可为后期水文地质数值模拟提供基础数据。     

西安轨道交通二号线B标段水文地质特征分析

为了给西安轨道交通B标段车站基坑开挖降水设计及区间隧道洞室盾构机掘进参数提供水文地质依据,对该标段的工程地质、水文地质勘察资料进行了分析,得出该标段地下水既有潜水又有承压水,两者间的隔水层不连续,存在“天窗”并发生水力联系的结论。地铁建筑物位于潜水含水层中,该含水层属于以中砂为主的强透水层,通过抽水试验并反求出含水层参数,对可能引起的基坑渗透破坏及地表沉降作了系统分析与评价。     

齐齐哈尔市地下水环境污染预测

齐齐哈尔市地下水环境的现状评价和影响预测表明:潜水含水层已受到较严重污染,承压水也正受到污水氧化塘的污染。建议尽快开展地下水环境管理研究,以保证地下水资源的可持续开发利用。     

渭河临潼段漫滩沉积物渗透系数分析

河漫滩沉积物渗透系数空间变异性特征对流域生态环境修复与保护具有重要意义。为研究河漫滩沉积物渗透系数空间变异性特征,采用双环试验法和竖管试验法,分别选取渭河临潼段内6个试验段合计6个非饱和试验点、138个饱和试验点渗透系数进行研究,并通过地统计学法进行分析,发现渭河漫滩非饱和带渗透系数和饱和带渗透系数分别介于1.30~6.08 m/d和0.002~1.763 m/d之间,结果表明:渭河临潼段漫滩沉积物非饱和渗透系数较大,饱和渗透系数较小;河漫滩饱和渗透系数沿河符合正态分布且变异性较强;河漫滩饱和渗透系数空间相关性较弱,但均具有空间自相关性。研究结果为渭河流域地表水和地下水转换关系研究提供了理论和数据支持。     

天山北坡经济带东段浅层地下水固有脆弱性评价

基于改进的DRASTIC方法,选择地下水埋深、含水层净补给量、含水层岩性、土壤介质类型、地面坡度、浅层地下水水质、包气带介质类型、含水层渗透系数和潜水蒸发量9项评价指标,分别确定其评分体系和权重体系,并利用Arc Gis 10.2中的图层空间叠加分析功能,对天山北坡经济带东段地区的浅层地下水固有脆弱性进行评价。结果表明:脆弱性较高区和中等区占研究区总面积的80.17%,地下水整体脆弱性偏高,而导致研究区浅层地下水脆弱性偏高的主要因素为地下水埋深较小、含水层渗透性较强、浅层地下水水质差。     

快速评价海水入侵区地层渗透性实验研究

为快速评价海水入侵区不同埋深地层渗透性,减少实施常规水文地质试验对存在污染含水层的扰动,提出利用振荡试验技术确定滨海地层渗透系数。室内海水入侵砂槽物理模型中实施了注水式振荡试验,在人工潜水含水层和承压含水层中同步监测了试验主井和相邻观测井中水位响应;龙口海水入侵区地下水分层监测井中实施了提水式和注水式振荡试验;利用配线法计算了室内实验和现场实验中目标地层渗透系数。结果表明：海水入侵砂槽物理模型中实施振荡试验为滨海含水层现场利用振荡试验确定不同埋深含水层渗透系数提供了重要经验;相比于提水式振荡试验,注水式振荡试验更易于实施,激发方式（提水和注水）的不同并没有对试验结果造成明显的影响;利用振荡试验在非常短时间内（单井水位恢复时长大部分少于5 min）确定了龙口海水入侵区重要监测断面上不同埋深含水层渗透系数,实验结果准确可靠。     

Groundwater Response to Tidal Fluctuation in an Inhomogeneous Coastal Aquifer-Aquitard System

This paper investigates tide-induced groundwater fluctuation and submarine groundwater discharge (SGD) in a leaky inhomogeneous coastal aquifer system with an upper unconfined aquifer, a lower confined aquifer, and an aquitard between them. The upper left aquifer is formed due to land reclamation. The SGD defined as the groundwater flow from land into the sea is controlled mainly by the hydraulic gradient between land and sea. An analytical expression is developed to discuss and assess the effect of inhomogeneity on the groundwater head fluctuation in the leaky aquifer system. Joint effects of aquifers’ parameters such as leakage and hydraulic diffusivity on the groundwater head fluctuation and SGD are investigated. The predicted results from the analytical expression indicate that the groundwater head fluctuation in both unconfined and confined aquifers is dependent on dimensionless leakages and increases with dimensionless hydraulic diffusivity.     

一种基于MATLAB的渗透系数确定方法

地下水资源评价与地下水可开采量计算需要对地下含水层参数进行分析确定。结合托克托县地区抽水试验,运用MATLAB软件优化传统的Jacob直线图解法和标准曲线配线法,在单孔非稳定流抽水试验中确定承压含水层导水系数T和渗透系数K,计算结果符合当地水文地质条件,且比传统方法精确可靠。     

云神经网络确定含水层参数研究

高效、精确的含水层参数求解方法一直是水文地质研究领域的重要研究内容之一。实践中通常利用非稳定流抽水试验资料通过配线法确定含水层参数,但是随着计算机应用的普及,已有人开发出几种在非稳定流试验条件下求解含水层水文地质参数的快速、精确的计算机智能优化算法。在此基础上尝试建立了云神经网络模型(Cloud Neural Net,CNN),并将其应用于石家庄市元氏县3个单孔非稳定流抽水试验,对承压含水层参数进行计算,模型计算结果与当地的水文地质条件较为符合,且比传统方法及单纯的人工神经网络模型所得结果更加精确。因此云神经网络模型为研究区地下水资源评价、地下水数值模拟以及溶质运移模拟提供了另一种重要手段。     

Hydraulic Parameters of Coastal Aquifer Systems by Direct Methods and an Extended Tide–Aquifer Interaction Technique

Adequate and reliable parameters are key to the sustainable management of vital groundwater resources. Present study focuses on the evaluation of direct methods (tidal efficiency and time lag methods) and an extended tide–aquifer interaction technique for determining the hydraulic parameter of coastal unconfined and confined aquifer systems. The hydraulic diffusivities of unconfined and confined aquifer systems were estimated using the tidal efficiency and time lag methods as well as they were optimized using the tide–aquifer interaction model and the Levenberg–Marquardt optimization technique. The hydraulic diffusivities were optimized by the Levenberg–Marquardt technique following two approaches: lumped tidal component approach and multi-tidal component approach. The effect of spring and neap tidal data on parameter estimates was also analyzed. The tide–aquifer interaction data for two unconfined sites and three confined sites were used in this study. For all the five sites under study, the aquifer hydraulic diffusivities based on the time lag method were found to be much larger (2 to 14 fold for the unconfined sites and 5 to 8 fold for the confined sites) than those based on the tidal efficiency method. The analysis of the optimization results indicated that the hydraulic diffusivities following “multi-tidal component approach” are more reliable and accurate for both unconfined and confined aquifers than those obtained following “lumped tidal component approach”. Consequently, the use of “multi-tidal component approach” is strongly recommended for the determination of aquifer parameters by the tide–aquifer interaction technique. Furthermore, the tide–interaction data corresponding to spring and neap tidal events were found to significantly affect the aquifer diffusivities yielded by the tide–aquifer interaction technique. It is concluded that a judicious use of tide–aquifer interaction technique is indispensable for the reliable estimates of hydraulic parameters of coastal aquifer systems.     

巴音河下游河床渗透系数空间变异性研究

河床垂向渗透系数是研究河流与地下水转化关系和转化强度的重要水文地质参数。选取柴达木盆地巴音河为研究对象,采用水头下降竖管试验法测定了巴音河下游细土平原带38组河床垂向渗透系数,利用传统统计学方法检验分析了其分布规律和空间变异性。结果表明,河床沉积物垂向渗透系数(Kv)在1. 77～15. 56 m/d之间变化,总体呈现正态分布,且沿流程逐渐变小。河中心沉积物的Kv值明显大于河两岸,但其变异系数小于两岸。沉积物的颗粒大小与分布是导致河床沉积物垂向渗透系数变异的关键因素,河流形态与交互带水文过程对河床沉积物Kv的影响也不容忽视。     

Characterization of a Regional Aquifer System in the Maritimes Basin,Eastern Canada

A regional hydrogeological study was carried out in the Maritimes provinces, in one of the main aquifer systems in Canada. The study area covers a land surface of 10,500 km², of which 9,400 km² is over Carboniferous and younger rocks. The sedimentary fractured bedrock is composed of a sequence of discontinuous strata of highly variable hydraulic properties, and is overlain by a thin layer of glacial till (mostly 4 to 8 m). Depending on areas, 46 to 100% of the population relies on groundwater for water supply. Almost all residential wells are shallow (28 m on average) open holes that are cased only through the surficial sediments. This paper describes a regional hydrogeological investigation based on targeted fieldwork, the integration of a wide variety of existing multisource datasets and groundwater flow numerical modelling. The aim of this paper is to present the current state of understanding of the aquifer system in a representative area of the Maritimes Basin, along with the methodology used to characterize and analyze its distinct behaviour at the regional, local and point scales. This regional hydrogeological system contains confined and unconfined zones, and its aquifer lenticular strata extend only a few kilometers. Preferential groundwater recharge occurs where sandy tills are present. The estimated mean annual recharge rate to the bedrock aquifers ranges between 130 and 165 mm/year. Several geological formations of this Basin provide good aquifers, with hydraulic conductivity in the range of 5 × 10⁻⁶ to 10⁻⁴ m/s. Based on numerical flow modelling, faults were interpreted to play a key role in the regional flow. Pumping test results revealed that the aquifers can locally be very heterogeneous and anisotropic, but behave similarly to porous media. Work performed at the local scale indicated that most water-producing fractures generally have a sub-horizontal dip along a north-east (45°) strike.     

彭阳县饮用地下水氟离子含量空间变异性及其与地质环境的关系

通过对彭阳县74个饮用地下水进行取样分析,应用地质统计学的理论和方法,通过计算变异函数和克里金插值,分析研究了彭阳县饮用地下水中氟离子含量空间变异特征和空间分布特征,讨论了氟离子含量空间分布特征与地质环境的关系.结果表明:彭阳县存在引用地下水氟离子含量超标的现象,属于典型的高氟地下水区;地下水氟离子含量呈现明显的各向同性特征,在一定范围内具有很强的空间自相关性,且空间变异性是由大尺度的区域性因素引起的,而随机因素的影响不显著;空间分布上呈现出由南北向中间和由西向东减小的趋势;地下水中氟离子含量的差异是在各种地质环境因素共同作用下形成的,是地下水径流过程中各种因素综合影响的结果.     

A Generalized Predictive Model of Water Table Fluctuations in Anisotropic Aquifer Due to Intermittently Applied Time-Varying Recharge from Multiple Basins

Mathematical models play a key role in assessing the future behavior of a groundwater system in response to various schemes of ground water resources development such as artificial recharging and in selecting an appropriate one out of many proposed schemes for its sustainable development. This paper presents an analytical solution of groundwater flow equation for unconfined, anisotropic, 2-D rectangular aquifer under the Boussinesq approximation to predict water table fluctuations in the aquifer in response to general time-varying intermittent recharge from multiple rectangular infiltration basins of different spatial dimensions. The horizontal anisotropy incorporated in the model is such that the principal axes of the hydraulic conductivity tensor are oriented parallel to the rectangular sides of the aquifer. The time-varying recharge rate is approximated by a series of line elements of different lengths and slopes depending on the nature of variation of recharge rate. The solution is obtained by using extended finite Fourier sine transform. Application of the solution is demonstrated with the help of synthetic examples. Numerical results of the analytical solutions are verified by comparison with the results obtained from MODFLOW. Numerical results indicate significant effect of anisotropy in hydraulic conductivity on the nature of water table variation.     

The influence of stream bed hydraulic conductivity on sustaining baseflow in rivers.

This study presents the results of the influence of stream bed hydraulic conductivity on baseflow sustainability by using a coupled model of surface and subsurface hydrology. The model provides a coupled solution to the dynamic interactions between a river and a surfacial aquifer and is used to numerically study the effect of stream bed conductivity on the overall system response. To achieve this objective, the model is formulated to include a one-dimensional river flow model and a two-dimensional vertically averaged groundwater flow model in an unconfined aquifer. The coupling is achieved at the river bed via a hydraulic flux that is described as a function of river bed conductivity and the gradient between river stage and groundwater head. The model incorporates the concept of simultaneous presence of the two hydrologic processes for simulating the dynamic interactions and uses a novel numerical technique to solve the two systems concurrently. These interactions are analyzed by numerical experimentation under different hydraulic conductivity conditions. The influence of hydraulic conductivity and hydraulic gradient is studied under steady and unsteady flow regimes to assess the occurrence of baseflow. The analysis also reveals critical insights into the governing mechanisms that provide and sustain the baseflow in rivers.