基于水化学和同位素特征的新乡某地下水污染场地水文地质概念模型细化

构建合理的水文地质概念模型对于地下水数值模拟至关重要,概念模型如果确定不合理,整个数值模拟将毫无意义。通常水文地质调查可以大致确定水文地质概念模型,然而对于一些不易被发现的补给源,通过水文地质调查也无法确定。水化学和同位素特征对地下水的补给源及水流路径有很好的指示作用,可以根据这些信息对水文地质概念模型进行细化。文章通过对研究区地下水取样,分析地下水水化学和同位素特征,确定出研究区内不易识别的地下水补给源及顶层黏土-粉质黏土的透水性,最终细化了水文地质概念模型边界条件。这对于后期得到正确的地下水流和溶质运移模拟结果具有重要意义。     

昆明地热田岩溶地下热水系统中溶质运移的模拟

通过对昆明地热田深层基岩地下热水系统的地质、水文地质条件和开采现状的分析,建立了考虑温压变化和越流条件的岩溶热储层中地下热水的水流和溶质(污染物)运移的准三维非稳定流数学模型。对开采条件下地热田Ⅱ 块段地下热水系统中水位及F- 、Cl- 、NH+4 、SO2-4 浓度的模拟结果表明,所建立的模型合理、可靠,具有较高的仿真性。模型可预测不同条件下地热田地下热水的流场和溶质浓度的动态变化趋势,为防治地下热水环境的进一步恶化提供参考。      

Characterization of the groundwater flow system in the hillside and coastal aquifers of the Mersin-Tarsus region (Turkey)

In the region between Mersin and Tarsus cities, located along the Mediterranean Sea coast in southern Turkey, the demand for groundwater has increased dramatically as the available surface water supplies have already been developed. Fundamental information is required to characterize the existing groundwater system in this area in order to establish a sustainable groundwater-use policy. For this purpose, hydrochemical and environmental isotopic data were collected and integrated with available geological and hydrogeological information to develop a conceptual model of the system. Results, backed up mainly by depleted stable isotope composition and infinitesimal tritium content, suggest that most of the groundwater along the coastal zone is supplied by the neighboring mountain belt while local precipitation has also contributes to aquifer recharge. The validation of the conceptual perspective by a steady-state numerical groundwater flow model reveals that about 90% of the recharge to the aquifer system is supplied by the deep flow of karstic groundwater fed from the Taurus Mountains. Monitoring of changes in the recharge regime of the mountain sector seems to be critical in establishing future groundwater use policies.     

The effect of graben structures on the migration of groundwater contaminants at an industrial site

Industrial sites present a challenge to the hydrogeological delineation of pollution sources and their impacts. When large-scale geologic structures such as grabens exist on such sites, these can have a significant impact on the hydrology and water quality distribution. At the site investigated, geophysical techniques, standard hydrogeological approaches and hydrochemical characterisation (with methods such as depth-profiling and isotopes) were used to determine the impact of a graben structure and the hydrogeological properties and consequent water quality distribution. Zones of high conductivity, corresponding with available data, were identified from the geophysical investigation and subsequent pumping tests in the area. Through hydrochemical characterisation, including isotopes, it was determined that the fault zone acts as a barrier for groundwater flow and is thus the reason for the lower levels of pollutants in groundwater beyond this feature. However, the surface water flow is not restricted by these zones, and contributes significantly to the flow and salt loads at the discharge point. The study showed that graben structures are important controls on the movement of contaminants, and that the effect of such geological features on groundwater quality distribution must be investigated using multiple methodologies to construct a feasible conceptual model of the interactions.     

Multi-scale aquifer characterization and groundwater flow model parameterization using direct push technologies

Direct push (DP) technologies are typically used for cost-effective geotechnical characterization of unconsolidated soils and sediments. In more recent developments, DP technologies have been used for efficient hydraulic conductivity (K) characterization along vertical profiles with sampling resolutions of up to a few centimetres. Until date, however, only a limited number of studies document high-resolution in situ DP data for three-dimensional conceptual hydrogeological model development and groundwater flow model parameterization. This study demonstrates how DP technologies improve building of a conceptual hydrogeological model. We further evaluate the degree to which the DP-derived hydrogeological parameter K, measured across different spatial scales, improves performance of a regional groundwater flow model. The study area covers an area of ~60 km² with two overlying, mainly unconsolidated sand aquifers separated by a 5–7 m thick highly heterogeneous clay layer (in north-eastern Belgium). The hydrostratigraphy was obtained from an analysis of cored boreholes and about 265 cone penetration tests (CPTs). The hydrogeological parameter K was derived from a combined analysis of core and CPT data and also from hydraulic direct push tests. A total of 50 three-dimensional realizations of K were generated using a non-stationary multivariate geostatistical approach. To preserve the measured K values in the stochastic realizations, the groundwater model K realizations were conditioned on the borehole and direct push data. Optimization was performed to select the best performing model parameterization out of the 50 realizations. This model outperformed a previously developed reference model with homogeneous K fields for all hydrogeological layers. Comparison of particle tracking simulations, based either on the optimal heterogeneous or reference homogeneous groundwater model flow fields, demonstrate the impact DP-derived subsurface heterogeneity in K can have on groundwater flow and solute transport. We demonstrated that DP technologies, especially when calibrated with site-specific data, provide high-resolution 3D subsurface data for building more reliable conceptual models and increasing groundwater flow model performance.     

悦康药业地下水环境数值模拟预测与评价

悦康药业在开发和生产过程中可能会对区域地下水环境造成影响。基于研究区水文地质条件,建立水文地质概念模型,分别对拟开采的第Ⅲ承压含水层,运用水流运动方程对项目开采15年后的地下水位进行模拟预测;运用溶质运移数学模型对药厂建成后污水处理站对潜水和第Ⅰ承压水进行污染物模拟预测。水位模拟结果表明,15年后含水层(组)中形成降落漏斗大于1 m的范围为0. 45 km~2,形成地面沉降的可能性较小。污染物模拟预测选取COD_(Mn)、氨氮作为预测因子,分别预测污染发生100天、720天及1 800天后污染物迁移情况。污染物模拟结果表明污水站溶质扩散范围较小,5年后COD_(Mn)最大迁移距离为40 m,中心体积质量降为5. 0 mg/L;氨氮最大迁移距离为35 m,中心体积质量降为0. 3 mg/L,对区域地下水水质影响不大。     

The impact of tunneling construction on the hydrogeological environment of “Tseng-Wen Reservoir Transbasin Diversion Project” in Taiwan

Groundwater flow and the associated surface water flow are potential negative factors on underground tunnels. Early detection of environmental impacts on water resources is of significant importance to planning, design and construction of tunnel projects, as early detection can minimize accidents and project delays during construction. The groundwater modeling software package Groundwater Modeling System (GMS), which supports the groundwater numerical codes MODFLOW and FEMWATER, was utilized to determine the impact of tunneling excavation on the hydrogeological environment in a regional area around the tunnel and a local hot springs area, at the “Tseng-Wen Reservoir Transbasin Diversion Project”, in Taiwan. A hydrogeological conceptual model was first developed to simplify structures related to the site topography, geology and geological structure. The MODFLOW code was then applied to simulate groundwater flow pattern for the hydrogeological conceptual model in the tunnel area. The automated parameter estimation method was applied to calibrate groundwater level fluctuation and hydrogeological parameters in the region. Calibration of the model demonstrated that errors between simulated and monitored results are smaller than allowable errors. The study also observed that tunneling excavation caused groundwater to flow toward the tunnel. No obvious changes in the groundwater flow field due to tunnel construction were observed far away in the surrounding regions. Furthermore, the FEMWATER code for solving 3-D groundwater flow problems, in which hydrogeological characteristics are integrated into a geographic information system (GIS), is applied to evaluate the impact of tunnel construction on an adjacent hot spring. Simulation results indicated that the groundwater drawdown rate is less than the groundwater recharge rate, and the change to the groundwater table after tunnel construction was insignificant for the hot spring area. Finally, the groundwater flow obtained via the GMS indicated that the hydrogeological conceptual model can estimate the possible quantity of tunnel inflow and the impact of tunnel construction on the regional and local groundwater resources regime of the transbasin diversion project.     

大区域地下水流数值模拟研究现状及存在问题

在分析大区域地下水流数值模型构建缘起的前提下,系统论述了近年来地下水流数值模拟在大区域地下水资源评价、水文地质参数确定、地面沉降、溶质运移、海水入侵、盐渍化、风险评估、地下水管理及地表水与地下水的联合开发利用等方面的国内外研究应用现状;归纳、总结了目前大区域地下水流数值模型在灵敏度分析、裂隙和岩溶介质中模型建立、基于地下水流数值模拟的溶质运移模型建立、地下水流数值模型构建所需工作量等理论和方法研究及实际建模过程中存在的一些问题;展望了今后大区域地下水流数值拟在研究范围、模拟技术与方法以及与其它模型耦合等方面的发展趋势。      

鄂尔多斯盆地盐池-定边地区水化学场分布特征及形成机理

根据盐池-定边地区水化学场分布特征及其自然地理、地质构造、水文地质背景、岩相古地理和古水文地质条件，以水文地球化学理论为指导，采取野外水文地质调查、水样采集与测试及水文地球化学方法分析研究了该水化学场的形成机理及影响因素.研究表明，鄂尔多斯盆地盐池-定边地区水化学场分布主要有SO₄·Cl-Na·Mg型、HCO₃·SO₄-Na型、HCO₃·Cl-Na·Ca型和HCO₃-Ca·Na型场，在白于山分水岭向北和西北的水平分带明显，水化学场与地下水流向呈逆向分布.本区水化学特征主要受古沉积中心及地层原始含盐量、地质构造、混合作用、地下水运动规律、古地下水等综合因素的影响.     

利用稳定同位素方法识别内蒙古佘太盆地地下水补给来源

为研究近几十年来佘太盆地地下水补给变化情况,通过现场调查分析,对佘太盆地浅层地下水开展同位素样品采集工作,并测定了其氢、氧稳定同位素的值。在分析同位素分布特征及变化规律的基础上,结合当地地质及水文地质条件识别了地下水补给来源和补给区并构建了浅层地下水的补给模式图,探讨了区域上浅层地下水的补给流动状况。通过分析研究区大气降水和地下水中的氢氧稳定同位素的变化特征发现:当地大气降水并不是地下水的主要补给来源,其补给源区为周边山区,补给来源主要是周边山区的大气降水,且地下水所经历的蒸发作用较明显;盆地的东、西部地下水的补给源区不尽相同,西部的补给区高程要高于东部的补给区高程,但两部分地下水所经历的蒸发强度基本相同。     

Application of multiple-point geostatistics on modelling groundwater flow and transport in a cross-bedded aquifer (Belgium)

Sedimentological processes often result in complex three-dimensional subsurface heterogeneity of hydrogeological parameter values. Variogram-based stochastic approaches are often not able to describe heterogeneity in such complex geological environments. This work shows how multiple-point geostatistics can be applied in a realistic hydrogeological application to determine the impact of complex geological heterogeneity on groundwater flow and transport. The approach is applied to a real aquifer in Belgium that exhibits a complex sedimentary heterogeneity and anisotropy. A training image is constructed based on geological and hydrogeological field data. Multiple-point statistics are borrowed from this training image to simulate hydrofacies occurrence, while intrafacies permeability variability is simulated using conventional variogram-based geostatistical methods. The simulated hydraulic conductivity realizations are used as input to a groundwater flow and transport model to investigate the effect of small-scale sedimentary heterogeneity on contaminant plume migration. Results show that small-scale sedimentary heterogeneity has a significant effect on contaminant transport in the studied aquifer. The uncertainty on the spatial facies distribution and intrafacies hydraulic conductivity distribution results in a significant uncertainty on the calculated concentration distribution. Comparison with standard variogram-based techniques shows that multiple-point geostatistics allow better reproduction of irregularly shaped low-permeability clay drapes that influence solute transport.     

水质监测在识别水动力条件中的作用

水质监资料不仅可反映地下水水质的时、空变化特征，而且可提供有关地下水赋存环境、循环深度、流速、资源量组成等方面的重要信息。     

山东淄博市地下水资源评价及其合理开发利用研究

本文采用有限单元法进行地下水资源评价以解决评价区供水面积大、精度要求高的矛盾。首先根据实际的开采量和长期观测孔的水位资料,校正数学模型,反求有关参数;然后给定开采方案进行未来水头的预测;最后研究地下水资源的合理开发利用问题。利用有限单元法进行水源地或单一含水层的地下水资源评价已被证明是先进的、有效的。本文是对水文地质条件非常复杂的大面积的区域,用有限单元法进行地下水资源评价的一种尝试,可供类似地区参考。     

The hydrogeology of the Ballimore region,central New South Wales,Australia: an integrated study

The integrated use of geophysical, geological, hydrogeochemical and hydrogeological data has allowed the development of a plausible conceptual model for groundwater flow in the Ballimore region. A realistic model for this under-explored system could not be derived solely by the use of hydrogeological data. Interpretation of the available datasets indicates that two groundwater systems are active: a regional and a local system. These are separated by a regionally extensive aquiclude. Groundwater flow in the regional groundwater system is controlled by the structural fabric of the Palaeozoic basement rocks. The local groundwater system is restricted to the Permian to Recent sequence of cover rocks. The local groundwater system is subdivided into three cells: the deep, intermediate and shallow cells. Groundwater flow within the deep cell of the local groundwater system is controlled by fracture flow. Groundwaters from this aquifer are under artesian pressure and are effervescent (CO₂-gas). The intermediate cell is a leaky aquitard that acts as a mixing zone between the deep and shallow cells. Groundwater flow within the shallow cell is controlled by the influx of surface waters which migrate laterally through permeable beds.     

Assessing Groundwater Resource Vulnerability by Coupling GIS-Based DRASTIC and Solute Transport Model in Ajmer District,Rajasthan

Groundwater aquifer vulnerability has been assessed by incorporating the major geological and hydrogeological factors that affect and control the groundwater contamination using GIS-based DRASTIC model along with solute transport modeling. This work demonstrates the potential of GIS to derive a vulnerability map by overlying various spatially referenced digital data layers (i.e., depth to water, net recharge, aquifer media, soil media, topography, the impact of vadose zone and hydraulic conductivity) that portrays cumulative aquifer sensitivity ratings in Kishangarh, Rajasthan. It provides a relative indication of groundwater aquifer vulnerability to contamination. The soil moisture flow and solute transport regimes of the vadose zone associated with specific hydrogeological conditions play a crucial role in pollution risk assessment of the underlying groundwater resources. An effort has been made to map the vulnerability of shallow groundwater to surface pollutants of thestudy area, using soil moisture flow and contaminant transport modeling. The classical advection-dispersion equation coupled with Richard’s equation is numerically simulated at different point locations for assessing the intrinsic vulnerability of the valley. The role of soil type, slope, and the land-use cover is considered for estimating the transient flux at the top boundary from daily precipitation and evapotranspiration data of the study area. The time required by the solute peak to travel from the surface to the groundwater table at the bottom of the soil profile is considered as an indicator of avulnerability index. Results show a high vulnerability in the southern region, whereas low vulnerability is observed in the northeast and northern parts. The results have recognized four aquifer vulnerability zones based on DRASTIC vulnerability index (DVI), which ranged from 45 to 178. It has been deduced that approximately 18, 25, 34, and 23% of the area lies in negligible, low, medium and high vulnerability zones, respectively. The study may assist in decision making related to theplanning of industrial locations and the sustainable water resources development of the selected semi-arid area.     

Modelling the evolution of hydrochemical conditions in the Fennoscandian Shield during Holocene time using multidisciplinary information

Three-dimensional, large-scale models for groundwater flow and solute transport are used for the low-temperature, fractured crystalline rock sites in Sweden that are being considered for the geological disposal of spent nuclear fuel. It has been suggested that comparisons between measured and simulated present-day hydrochemical data provide a means to constrain the complex influences of past climatic events and to improve the ability to understand the palaeohydrogeological evolution of the physical system studied. Here the authors demonstrate how the integration of multidisciplinary data and models from one of the sites in Sweden (Forsmark) can aid the appraisal of the hydrochemical conditions at 8000 BC, which is the selected starting point for the palaeohydrogeological modelling of the hydrochemical conditions in the Fennoscandian Shield during the Holocene (last 10 ka). Since a firm understanding of the evolution of the hydrochemical conditions is important for the long-term safety assessment, recognition of the initial hydrochemical conditions is essential for the overall build-up of confidence in the modelling process.     

The southeastern border of the Upper Rhine Graben: a 3D geological model and its importance for tectonics and groundwater flow

A 3D geological model of the area east of Basel on the southeastern border of the Upper Rhine Graben, consisting of 47 faults and six stratigraphic horizons relevant for groundwater flow, was developed using borehole data, geological maps, geological cross sections, and outcrop data. This model provides new insight into the discussions about the kinematics of the area between the southeastern border of the Upper Rhine Graben and the Tabular Jura east of Basel. A 3D analysis showed that both thin-skinned and thick-skinned tectonic elements occur in the modeled area and that the Anticline and a series of narrow graben structures developed simultaneously during an extensional stress-field varying from E–W to SSE–NNW, which lasted from the Middle Eocene to Late Oligocene. In a new approach the faults and horizons of the 3D geological model were transferred into discrete elements with distributed hydrogeological properties in order to simulate the 3D groundwater flow regime within the modeled aquifers. A three-layer approach with a horizontal regularly spaced grid combined with an irregular property distribution of transmissivity in depth permitted the piezometric head of the steady-state model to be automatically calibrated to corresponding measurements using more than 200 piezometers. Groundwater modeling results demonstrated that large-scale industrial pumping affected the groundwater flow field in the Upper Muschelkalk aquifer at distances of up to 2 km to the south. The results of this research will act as the basis for further model developments, including salt dissolution and solute transport in the area, and may ultimately help to provide predictions for widespread land subsidence risks.     

高放废物处置库北山预选区区域水文地质概念模型

地下水流数值模拟是高放废物处置库选址中水文地质评价的重要内容.水文地质概念模型是地下水流数值模拟的基础和前提.在北山预选区水文地质分析基础上,利用DEM数据生成了研究区地表水系,据此确定了模拟范围;借助GMS软件,建立了研究区三维水文地质结构模型;再通过边界条件、流场特征、地下水均衡项和水文地质参数的分析和描述,建立了北山地区水文地质概念模型.