天津市地下水流-地面沉降耦合模型

天津市平原区地面沉降主要由地下水大量开采引起,影响范围广、危害大,已成为天津市主要的环境地质问题。分析了研究区的水文地质条件,结合地下水开发利用状况,将研究区概化为6个含水层组,地下水流考虑三维非稳定流,地面沉降选用一维固结压缩模型,运用地下水流模型Modflow 2005和地面沉降模拟模块 Sub,建立了天津市平原区地下水流-地面沉降数值耦合模型,模型面积为1.1×10⁴ km²,利用1998-2008年地下水位等值线、过程线、地面沉降过程线等资料对模型进行了识别。模拟期的地下水均衡分析表明,在多年开采条件下,越流补给、压缩释水、侧向边界流入分别占深层含水层补给量的41.84％、32.15％和24.17％。将调试后的模型应用于南水北调实施后地下水控采条件下的地面沉降趋势预测,显示出停采或减少地下水的开采,有利于减缓地面沉降下降速度,且表现出开采层位越往下,地面沉降恢复难度越大的变化趋势。     

大兴迭隆起隐伏岩溶水资源评价及开采方案预测

大兴迭隆起地区隐伏岩溶地下水是北京市的重要水源,为保障水源地能持续为大兴、通州地区提供优质的城镇生活用水,需对研究区岩溶地下水进行水资源评价和开采规划预测分析。利用数值模拟法,应用GMS模拟软件对研究区岩溶水系统进行地下水流数值模拟及水位变化预测。建立的岩溶水系统模型分为5层,模拟验证期为12年9个月。由模型评价的岩溶水系统补给资源量为14 425.74×10^4m3/a,可开采资源量为14 310.52×10^4m3/a,其中岩溶含水层可开采量为2 309.36×10^4m3/a。在模型识别验证后,分4种开采方案对水源地进行开采预测,通过对典型观测孔水位过程线拟合和研究区水均衡分析可知,按2020年之前维持现状开采,2020年后停采念坛水源地,2025年后全区按可开采量进行开采的开采方案最为合理,可分批逐次实现水源地的采补平衡。     

The Basin of Mexico aquifer system: regional groundwater level dynamics and database development

The aquifer system of the Basin of Mexico is the main source of water supply to the Mexico City Metropolitan Zone. Management of the Basin’s water resources requires improved understanding of regional groundwater flow patterns, for which large amounts of data are required. The current study analyses the regional dynamics of the potentiometric groundwater level using a new database called the Basin of Mexico Hydrogeological Database (BMHDB). To foster the development of a regional view of the aquifer system, data on climatological, borehole and runoff variables are part of the BMHDB. The structure and development of the BMHDB are briefly explained and then the database is used to analyze the consequences of groundwater extraction on the aquifer’s confinement conditions using lithology data. The regional analysis shows that the largest drawdown rates are located north of Mexico City, in Ecatepec (a region that has not yet received attention in hydrogeological studies), due to wells that were drilled as a temporary solution to Mexico City’s water-supply problem. It is evident that the aquifer has changed from a confined to an unconfined condition in some areas, a factor that is responsible for the large subsidence rates (40 cm/year) in some regions.     

天津市宁河县地下水安全AHP模糊评价浅析

由宁河县多年平均各含水组开采状况可知,第Ⅱ含水组开采比例占到了全县地下水总开采量的55%,开采强度在各含水组中也属最大,导致了该层地下水水位的持续下降,引起了地下水水质恶化、地下水资源枯竭、地面沉降等一系列环境地质问题。本文参考前人的研究成果,从地下水的安全内涵出发,构建了包括水质安全、水量安全、含水层安全和生态环境安全的4个一级评价指标,15个二级评价指标的地下水安全评价指标体系,建立了基于AHP的模糊综合评价模型,选取宁河县第Ⅱ含水组10个有代表性采样点进行安全现状分析,并在对地下水环境地质条件深入分析的基础上,量化了地下水安全评价分级标准,取得了与实际较为相符的结果。     

Assessing groundwater availability and the response of the groundwater system to intensive exploitation in the North China Plain by analysis of long-term isotopic tracer data

The use of isotope tracers as a tool for assessing aquifer responses to intensive exploitation is demonstrated and used to attain a better understanding of the sustainability of intensively exploited aquifers in the North China Plain. Eleven well sites were selected that have long-term (years 1985–2014) analysis data of isotopic tracers. The stable isotopes δ¹⁸O and δ²H and hydrochemistry were used to understand the hydrodynamic responses of the aquifer system, including unconfined and confined aquifers, to groundwater abstraction. The time series data of ¹⁴C activity were also used to assess groundwater age, thereby contributing to an understanding of groundwater sustainability and aquifer depletion. Enrichment of the heavy oxygen isotope (¹⁸O) and elevated concentrations of chloride, sulfate, and nitrate were found in groundwater abstracted from the unconfined aquifer, which suggests that intensive exploitation might induce the potential for aquifer contamination. The time series data of ¹⁴C activity showed an increase of groundwater age with exploitation of the confined parts of the aquifer system, which indicates that a larger fraction of old water has been exploited over time, and that the groundwater from the deep aquifer has been mined. The current water demand exceeds the sustainable production capabilities of the aquifer system in the North China Plain. Some measures must be taken to ensure major cuts in groundwater withdrawals from the aquifers after a long period of depletion.     

Numerical simulation of karst groundwater system for discharge prediction and protection design of spring in Fangshan District,Beijing

As the rapid growth of population and social economy, the situation of water resources shortage in Beijing city becomes more and more serious. Karst groundwater in Beijing has great potential for development. The reasonable exploitation of karst groundwater can enhance the water-supply stability of Beijing city. Firstly, the distribution of springs has been investigated in Fangshan, Beijing, and the characteristics of these springs have also been analyzed. Secondly, the hydrogeological conceptual model has been built, based on this, the groundwater flow numerical simulation model was established, and the parameter identification and validation of the model were performed under groundwater level and spring discharge. The results shows that the simulated values of groundwater level and spring discharge are very close to measured values, and the model can be used for groundwater resources evaluation and spring discharge prediction. Finally, a reasonable exploitation design has been developed with three exploitation scenarios considering the spring discharge protection; meanwhile, the quantity of groundwater resources was evaluated in the karst aquifer. The simulation results indicate that different exploitation yields have a significant impact on spring discharge; and the effective measures should be taken to protect the spring discharge     

冲洪积扇含水层地下水可开采量数值模拟——以文峪河冲洪积扇为例

依据钻孔岩性,水文地质资料,将文峪河冲洪积扇平原分为上游单一潜水区和中下游承压水区,中下游垂向划分为上部弱水含水层和下部较强承压水含水层,对上游潜水和中下游承压水用二维侧向流数学模型,对中下游弱潜水用一维垂向流数学模型,在计算了现状开采条件下的水资源基础上,进一步计算出,在扇上游集中采水时,按工业开采和农业开采,以地下水多年总补排均衡,水位长期稳定的约束条件地下水可开采量。     

The impact of salt diapirs on the quality of carbonate karst waters,Bastak, Iran

The Gavbast karstic aquifer located in southern Iran is in direct contact with an exposed salt diapir. To assess the influence of the diapir on the quality of groundwater in the karstic aquifer, electrical conductivity, total dissolved solids, flow rate, temperature and major ion concentrations were measured at 57 sampling sites, including springs, surface waters and wells. A conceptual model of groundwater flow is proposed for the Gavbast karstic aquifer based on the geological setting, water budget, local base of erosion, and hydrochemistry of the sampling sites. The model suggests two subbasins in the Gavbast Anticline draining into two distinct discharging alluvial sections. Unexpectedly, groundwater discharging from the carbonate Gavbast aquifer is saline or brackish and water is of chloride type. The study indicates that the source of salinity of the Gavbast aquifers is infiltration of surface diapir-derived brine into the aquifer. The contribution of the diapir brine in the Gavbast karst aquifer is calculated about 4 L/s, using chloride mass balance. Construction of salt basins to evaporate brine discharging from the diapir springs is proposed to reduce the salinity of karst water. A row of strategically placed wells in the Gavbast karst aquifer would potentially exploit large volumes of fresh groundwater before it is contaminated by the salt. Such low-cost remediation should allow the agricultural exploitation of 40 km² of currently barren land.     

埋藏型岩溶地下水源地的三维数值模拟——以天津市宁河北岩溶地下水源地为例

根据宁河北岩溶地下水源地已有的水文地质勘查成果和大型抽水试验资料,对研究区水文地质条件进行概化,建立地下水流三维非稳定流数学模型并进行数值计算,对开采性抽水试验的地下水位变化过程进行模拟。结果表明,该模型可以刻画埋藏型水源地地下水流场的变化过程,用它对规划的水源地三种开采方案的开采动态进行预测计算也取得了良好的效果。模拟计算中将开采条件下浅层第四系含水层对深层奥陶系灰岩含水层的越流补给处理为边界条件,可以刻画埋藏型水源地在开采条件下获得的补给增量。      

The effect of possible climate change on natural groundwater recharge based on a simple model: a study of four karstic aquifers in SE Spain

The study presented in this paper constitutes an initial approach to the problematic task of evaluating the effects of possible climate change on natural water recharge to aquifers. To estimate such effects, a purpose-designed mathematical model termed Estimation of Recharge in Over-exploited Aquifers (ERAS) has been used. It enables to simulate the monthly water recharge to an aquifer, provided that prior knowledge of the exploitation to which it is subjected and the variation caused by these two actions on the piezometric level of the aquifer is available. The basic data required for its application are: precipitation, temperature, groundwater extraction, stored groundwater surface and storage coefficient. The main advantage presented by this model is its independence of the mechanism by which water is displaced through the ground and within the unsaturated zone. The ERAS code was applied to four over-exploited karstic aquifers in Alto Vinalopó (Alicante, Spain) with the goal of generating a synthesized series of values for natural groundwater recharge in each of the aquifers for the 100 years of the twentieth century. Each series thus obtained after being grouped into decades was subjected to statistical processing, which revealed that in every case a logarithmically decreasing trend was present.     

An analysis of the infer-aquifer recharge for a deep-seated aquifer system tapped by a wellfield

Operation of a wellfield tapping a deep-seated aquifer system depends upon the recharge from outside the aquifer system under the condition of exploitation. This kind of replenishment, however, is not learned until the wellfield is in operation and a quarry-pumping test is often needed in the investigation of the wellfield. A deep-seated confined aquifer consisting of Ordovician carbonates occurs in the Chezhoushan Syncline crossing the border of Tianjin and Hebei in northern China. The Ordovician aquifer is believed to receive recharge through leakage from the overlying Quaternary aquifer only in the northeastern part of the syncline. The Ninghebei wellfield is planned to produce 100,000 m³/day of groundwater from the Ordovician aquifer for water supply. A three-dimensional transient numerical model was established based on a hydrogeologic survey, especially a quarry-pumping test conducted in 2003. The model was calibrated with the water-level data of the quarry-pumping test and used to predict the future water-level changes that might result from the three proposed exploitation scenarios. A 20 year predictive simulation results indicate that hydraulic heads decline rapidly in the early months, decline slowly in the following years and reach a steady state in the late period with a maximum drawdown of 52.09 m under the maximum total withdrawal rate of 120,000 m³/day from the Ordovician aquifer, and that the infer-aquifer recharge through leakage from the Quaternary aquifer can balance the withdrawal rate.     

山东烟台夹河中、下游地区海水入侵三维水质数值模拟研究

建立了三维变密度对流弥散水质数学模型来研究山东省烟台夹河中、下游地区咸淡水界面的运移规律。以四面体为基本离散单元 ,推导出三维海水入侵变密度水质模型求解的数值方法 ,其中水流方程求解时运用了迦辽金有限单元法。溶质运移方程求解时运用了欧拉拉格朗日混合方法 ,将对流项与弥散项分离 ,用传统迦辽金有限元方法求解弥散项 ;采用自适应MOC MMOC法求解对流项 ,以消除人工过量和数值弥散。根据地下水的潮汐效应观测信息 ,确定了含水系统的海底延伸边界 ;利用该地区地下水水头及水质长观资料识别了模型的水文地质参数 ,探讨了夹河地区海水入侵的原因 :认为夹河下游地区滨海地带地下水过量开采是造成烟台地区海水入侵的主要原因。此外 ,海水随潮定期地倒灌进入夹河 ,通过局部岩性天窗侵入淡水含水层加剧了沿夹河河床两侧地下水的咸化。同时还预测了几种情况下地下水的水质演化趋势 ,为防止和减轻夹河地区海水入侵提供合理、科学的依据。     

Alluvial aquifer recharge enhanced by a natural dam: feasibility assessment based on multidisciplinary characterization (Khuzestan,Southwest Iran)

In the Kushkak Valley (Khuzestan, Southwest Iran) an anticlinal structure has partially impounded an ephemeral stream. This natural impounded area has been chosen for an artificial recharge site due to its current rate of recharge, capability to store water and favorable situation for the construction of man-made barriers to stream flow. The aquifer to be recharged is the Kushkak unconfined aquifer which consists of medium to coarse-grained alluvial deposits that overlie consolidated conglomerate rock. In this semi-arid area with infrequent relatively heavy falls of rain, alluvial aquifer recharge can be an important process that sustains shallow, over-exploited groundwater bodies. In this investigation a multidisciplinary approach including: hydrometerological studies, and a detailed hydrogeochemical survey, have been carried out. Other essential prerequisite parameters for the scheme were also taken into account to determine the suitability of this location for groundwater artificial recharge. The assessment has brought out that (1) the proposed reservoir will conserve a major part of the water being lost, (2) annual runoff of about 0.27 MCM can be injected into the aquifer through recharge from impounded water, (3) hydrochemical data from surface water and from the Kushkak aquifer water demonstrates that dilution and change in compositional trend in the groundwater proximal to the impounded alluvial bed areas would be expected based on the infiltration capacity of this site, and (4) cost–benefit ratio of the project is 1:2 and it is assumed to recover the investment within six years.     

Impact of the unpredictable changes in agricultural groundwater use on long-term sustainable exploitation: the case study of Bouhefna-Haffouz aquifer system,central Tunisia

Long-term exploitation schemes in many regions are often based solely on hydrodynamic factors, while the agricultural use of groundwater undergoes significant changes over time. The Bouhefna-Haffouz aquifer system in central Tunisia is one of those cases where an aquifer exploitation scheme was well designed hydrodynamically to address the political needs at the time. Fifty years later, a numerical groundwater model has been conducted to assess the sustainability of the scheme. Results show that the scheme aimed to lower the groundwater level to reduce overflow to Merguellil Wadi and maintain it at a level that benefits agricultural profitability. This caused loss of the Merguellil baseflow, forcing farmers to switch from traditional irrigation canals to deep wells and motor pumps, thereby disrupting the hydrological budget even further. The numerical model indicates that the flow to the wadi reached zero in 1978, the average flow by vertical leakage decreased from 8 hm³ in 1970 to 2 hm³ in 2020, and the horizontal percolation between the regional aquifer units increased from 1 hm³ in 1970 to 6 hm³ in 2020. Although the groundwater exploitation scheme was not previously considered a factor in local hydrological changes, the results of this study demonstrate the significant impact of societal behavior following the scheme’s implementation on the hydrological budget of Merguellil Wadi.

     

冀东铁矿田的开发对区域地下水环境的影响

冀东铁矿田赋存在太古界单塔子群白庙子组中,资源量（332＋333）为25亿 t,平均品位〉30%,是我国重要的铁矿基地。矿区位于滦河冲洪积扇中上部,矿体上覆第四系砂砾卵石含水层富水性强,水量丰富,属于大水矿床,矿床疏干排水困难,疏干排水将破坏地下水环境。本文在分析矿区水文地质条件的基础上,提出了具有密切水力联系的多层含水层系统的水文地质概念模型,并建立了刻画多层含水层系统的数值仿真模拟模型,基于预留隔水顶板井下充填法采矿,预测矿山开采地下水流场演变,评价了矿山开采对区域地下水环境的影响,提出了环境保护措施,对今后矿山开发过程中的地下水环境影响评价方法、地下水资源开发利用及环保管理决策具有重要意义。     

北京市朝阳区沙子营垃圾污染物在潜水含水层中迁移规律的现场模拟实验

选择北京平原区水文地质、环境地质等方面都比较典型的沙子营垃圾堆放场,建立了其水文地质模型。在充分收集资料、分析得出部分计算所需参数后,采用现场弥散实验、勘查取样测试等方法,求得了该含水层的弥散系数等参数;用二维非稳定流溶质运移方程对污染物在此含水层中的迁移扩散规律、速度和污染范围等进行了模拟计算;采用现场钻探、取样测试分析等方法,评价了该含水层的实际污染状况。实验模拟计算和现场调查结果表明:污染物在潜水含水层中的运移规律遵循二维非稳定流场中的溶质运移方程,污染物在潜水含水层中的运移速度约为86.25m/a,迁移扩散主要发生在地下水流向上,侧向扩散宽度极小,是地下水流向上的1/17。     

上海市第四承压含水层变形特征研究

上海市自1968年调整开采层次以后,第四承压含水层逐渐成为地下水主要开采层次,历史上曾因过度开采利用地下水而成为主要的压缩土层。本文依据上海市长期的地下水位和地面沉降监测资料,总结了第四承压含水层在不同水位变化条件下的变形特征,同时根据压缩试验资料,对第四承压含水层变形机理探讨,为合理开发利用地下水资源提供理论依据。     

苏州城区地下水源热泵系统开发利用适宜性分区

以苏州城区为研究背景,阐述了浅层地温能资源赋存的水文地质条件,分析了地下水源热泵系统应用可能对地下水环境产生的影响,研究得出第Ⅱ承压含水层是该地区地下水源热泵开发利用的理想含水层.在此基础上,采用层次分析法和综合指数法建立适宜性分区标准,将苏州城区地下水源热泵系统应用划分为适宜区、一般适宜区和不适宜区,并进行了分区评价.为苏州城区地下水源热泵系统的合理开发利用和制定地下水环境保护措施等提供了重要依据.     

基于计点系统模型的地下水水量脆弱性评价

根据德阳市城市规划区的实际情况,选择含水层厚度、富水性、给水度、降水入渗系数、地下水资源可开采模数等能充分反应研究区地下水系统特征的5个指标,建立地下水水量脆弱性评价指标体系,利用专家评分法获取评价指标权重体系,并用计点系统模型及GIS技术进行研究区地下水水量脆弱性综合性评价。结果显示,地下水水量脆弱性较高和高的分布面积约占全区面积的29.7%,地下水水量保护管理形势较为严峻;发现地下水水量脆弱性在地下水补给区相对较低、在排泄区相对较高。     

丰沛平原区地下水开采利用现状及潜在水源地分析

通过总结丰沛平原区水文地质条件和特征,对该区地下水开采利用现状及潜在水源地进行分析,计算了华栖隆起区岩溶水可利用资源量,探讨裂隙岩溶水利用的可行性。研究表明: 丰沛平原区地下水主采层位为中上更新统孔隙含水层和新近系—下更新统孔隙含水层,已形成丰县城关—孙楼—常店和沛县—龙固2个大型超采漏斗区,总面积超过750 km²,引发了大面积地面沉降; 华栖隆起区为裂隙岩溶水的富水地段,总可采资源量为667.51万m³/a,可作为潜在水源地进一步开展地下水勘查评价工作; 裂隙岩溶水过量开采可能引发地面沉降、岩溶地面塌陷等地质灾害,后期应对裂隙岩溶水开采情况进行长期监测,合理开发利用水资源。华栖隆起区岩溶水距离城区近,水量大,水质好,开发难度小,具有可观的经济价值。