基于AquiferTest的抽水试验参数计算方法分析

抽水试验是水文地质勘查中最常用的水文地质试验,通过抽水试验,可准确计算水文地质参数。本文根据在河南豫东地区进行的抽水试验,分别用AquiferTest软件计算抽水试验参数和人工求参,进而进行对比分析得出:传统的人工求参,计算结果较为准确,可靠,但因人而异,有不唯一性;用AquiferTest软件计算抽水试验参数,规范、可比性好。本文最后还对参数取值问题进行了分析对比。     

传统公式法和Aquifer Test计算水文地质参数的对比分析

抽水试验是获取含水层水文地质参数的常用方法。参数计算结果精度直接关系到地下水资源评价精度和对区域水文地质条件的认识程度。以秦皇岛某水源地抽水试验为例,通过传统公式法和Aquifer Test专业软件对比分析发现:由于对水文地质条件认识的差异性,传统公式法与软件所计算的参数有一定误差,利用软件计算的结果基本符合实际的水文地质条件,可见,Aquifer Test软件用来计算水文地质参数方便快捷,计算结果直观精确,可比性好,值得推广应用。     

上海地区扁铲侧胀试验计算地基承载力的探讨

通过对扁铲侧胀试验和试验机理的研究和对试验指数的对比分析 ,提出了用扁铲侧胀试验计算地基承载力的方法 ;利用上海地区部分重大工程中的扁铲侧胀试验数据 ,在与室内土工试验、静力触探试验及十字板剪切试验的相关分析的基础上 ,经数理统计后给出了上海地区用扁铲侧胀试验计算地基承载力的经验公式。最后 ,通过与室内土工试验、静力触探试验和十字板剪切试验计算的地基承载力对比 ,分析了本经验公式计算地基承载力的精度。研究分析表明 ,可以用扁铲侧胀试验计算地基承载力     

单井注抽试验测算地下水流速的数值分析

为了分析注入阶段地下水流速及含水层弥散度对单井注抽试验解析模型测算地下水流速的影响机理,通过采用GMS(groundwater modeling system)软件建立了单井注抽试验数值模型,通过与Leap and Kaplan(1988)近似解析模型计算结果对比分析上述因素对解析模型计算结果的影响.研究结果表明:地下...     

基于MATLAB的地下水流量与水位降深关系的一种优化计算方法

相比理论公式法,基于最小二乘法原理及其计算方法,结合MATLAB数值分析软件对抽水试验数据进行曲线拟合,求得拟合公式,同时得Q—sw关系曲线的计算和绘制转化为计算机来处理,避免了手工绘制和计算求解时存在的各种人为缺陷;公式能够对勘探孔的Q—sw关系进行定性定量的分析,降低误差因素影响,提高预报流量的可信度。     

水泥石膏相似材料配比试验研究

采用水泥石膏相似材料制作标准试件模型,应用正交试验设计方法,以砂胶比、水泥石膏比、重晶石/骨料为3个因素,每个因素设置5个水平,设计了25组材料配比试验,进行了称重、单轴压缩、劈裂试验,获得了不同配比相似材料的密度、抗压强度、抗拉强度等物理力学性质指标。试验结果表明:不同配比的相似材料物理力学指标分布的范围较大,能够满足不同性质岩体模型试验对岩体相似材料的要求。基于MATLAB计算软件编制了用于正交试验设计和回归分析的软件,得到由水泥石膏相似材料密度、抗压强度和抗拉强度指标推算材料配比的经验公式。在以后的水泥石膏相似材料配比试验中可以用上述经验方程根据欲得到的材料物理力学指标进行配比设计。     

Aquifer test在某承压水抽水试验资料分析中的应用

近年来随着计算机技术的发展,水文地质工作者进行抽水试验资料分析的常用方法:求解水文地质参数配线法和直线法等均可借助计算机完成。本文以某承压水含水层为例,采用国际先进含水层试验软件Aquifer test对抽水试验数据进行分析,将其计算结果与传统计算结果、井流分析处理系统结果相对比,发现在抽水试验资料分析过程中,采用Aquifer test软件计算能借助计算机直接完成求参过程,提高抽水试验资料分析效率,是求解水文地质参数问题是行之有效的方法。     

基于Origin的渗透系数衰减方程在地热水回灌中的应用

孔隙型热储层的回灌过程中,由于物理堵塞、生物化学堵塞、悬浮物堵塞和气体堵塞,热储层的渗透性下降,回灌能力变弱.为了定量查明渗透系数的衰减,以辽南地区某回灌试验为例,使用Origin软件计算出研究区渗透系数衰减方程,在此基础上计算了回灌井灌压-时间关系曲线和回扬周期.研究表明,利用Origin软件求取渗透系数衰减方程具有...     

井损对水文地质参数计算的影响

通过分析抽水试验过程中井损产生的原因及确定方法,运用水位动态变化过程中的井损计算方法,对乌兰陶勒盖水源地WL6号孔的抽水试验资料的井损计算程序进行了说明,并提出了该水源地理想降深与实际降深的经验公式。利用Aqui Test软件,分别计算了忽略井损和考虑井损两种情况下潜水(承压水)抽水井渗透系数及给水度(贮水率),从计算结果来看,计算井损、修正降深所得的各参数的值要比不考虑井损的值大;井损对潜水的抽水试验资料的影响要比承压水的大。     

水文地质资料的计算机处理

结合科研和生产实践,编制了抽(放)水试验资料整理、计算程序,回归分析程序,随机模拟程序和剖分图绘制程序。论述了软件的开发背景、基本思路、所依据的基础理论和公式,以及程序设计的特点和技巧。      

基于Aquifer Test的含水层水文地质参数计算——以塔城市供水改扩建工程为例

水文地质参数的计算是水文地质勘察的一个重要环节。根据在塔城市北东方向喀拉墩地区进行的抽水试验资料,分别采用Aquifer Test软件和Dupuit公式迭代法计算抽水试验参数,对所求取的参数进行对比分析,通过Aquifer Test软件求取的参数与Dupuit公式迭代法求取的参数相近,各参数偏差率低,最终通过抽水试验数据,经不同的方法计算,确定含水层渗透系数K值为31.14 m/d。     

Geochemical and stable isotopic evolution of the Guarani Aquifer System in the state of São Paulo, Brazil

The purpose of this report is to explain geochemical and stable isotopes trends in the Brazilian unit of the Guarani Aquifer System (Botucatu and Piramboia aquifers) in S?o Paulo State, Brazil. Trends of dissolved species concentrations and geochemical modeling indicated a significant role of cation exchange and dissolution of carbonates in downgradient evolution of groundwater chemistry. Loss of calcium by the exchange for sodium drives dissolution of carbonates and results in Na–HCO₃ type of groundwater. The cation-exchange front moves downgradient at probably much slower rate compared to the velocity of groundwater flow and at present is located near to the cities of Sert?ozinho and águas de Santa Barbara (wells PZ-34 and PZ-148, respectively) in a shallow confined area, 50–70 km from the recharge zone. Part of the sodium probably enters the Guarani Aquifer System. together with chloride and sulfate from the underlying Piramboia Formation by diffusion related to the dissolution of evaporates like halite and gypsum. High concentrations of fluorine (up to 13.3 mg/L) can be explained by dissolution of mineral fluoride also driven by cation exchange. However, it is unclear if the dissolution takes place directly in the Guarani Aquifer System or in the overlying basaltic Serra Geral Formation. There is depletion in δ ²H and δ ¹⁸O values in groundwater downgradient. Values of δ ¹³C(DIC) are enriched downgradient, indicating dissolution of calcite under closed system conditions. Values of δ ¹³C(DIC) in deep geothermal wells are very high (>–6.0‰) and probably indicate isotopic exchange with carbonates with δ ¹³C about –3.0‰. Future work should be based on evaluation of vertical fluxes and potential for penetration of contamination to the Guarani Aquifer System. Electronic Publication     

The fluoride in the groundwater of Guarani Aquifer System: the origin associated with black shales of Paraná Basin

This work presents petrological and geochemical results of the black shales interval from Permian and Devonian strata of the Paraná Basin, Brazil and its relationships with fluoride of groundwater from Guarani Aquifer System. The Guarani Aquifer, located in South Brazil, Uruguay, Paraguay and Argentine, presents contents of fluoride higher than the Brazilian accepted potability limits. Several hypotheses have been presented for the origin of the fluoride in the groundwater of the Guarani Aquifer. Microcrystalline fluorite was registered in black shales of Ponta Grossa and Irati formations from Paraná Basin. The results shown in this work suggest that fluoride present in groundwater of Guarani Aquifer can be originated in deeper groundwater that circulates in Ponta Grossa and Irati formations. The interaction of the groundwater coming from deeper black shales with the groundwater-bearing Aquifer Guarani System occurs through regional fragile structures (faults and fractures) that constitute excellent hydraulic connectors between the two sedimentary packages. The microcrystalline fluorite registered in Ponta Grossa and Irati Formations can be dissolved promoting fluoride enrichment in groundwater of these black shales and Guarani Aquifer System.     

Integration of geoelectric and hydrochemical approaches for delineation of groundwater potential zones in alluvial aquifer

Geoelectric and hydrochemical approaches are employed to delineate the ground-water potential zones in District Okara, a part of Bari Doab, Punjab, Pakistan. Sixty-seven VES surveys are conducted with the Electrical Resistivity Meter. The resultant resistivity verses depth model for each site is estimated using computer-based software IX1D. Aquifer thickness maps and interpreted resistivity maps were generated from interpreted VES results. Dar-Zarrouk parameters, transverse resistance (TR), longitudinal conductance (SL) and anisotropy (λ) were also calculated from resistivity data to delineate the potential zones of aquifer. 70% of SL value is ≤3S, 30% of SL value is > 3S. According to SL and TR values, the whole area is divided into three potential zones, high, medium and low potential zones. The spatial distribution maps show that north, south and central parts of study area are marked as good potential aquifer zones. Longitudinal conductance values are further utilized to determine aquifer protective capacity of area. The whole area is characterized by moderate to good and up to some extent very good aquifer protective area on the basis of SL values. The groundwater samples from sixty-seven installed tube wells are collected for hydro-chemical analysis. The electrical conductivity values are determined. Correlation is then developed between the EC (μS/cm) of groundwater samples vs. interpreted aquifer resistivity showing R2 value 0.90.     

Groundwater modelling to help diagnose contamination problems

Aquifer remediation for a contaminated site is complex, expensive, and long-term. Groundwater modelling is often used as a tool to evaluate remedial alternatives and to design a groundwater remediation system. Groundwater modelling can also be used as a useful process to identify aquifer characteristics and contaminant behaviour that are not realized prior to modelling, to help diagnose what happened and why it happened at contaminant sites. Three real-world modelling cases are presented to demonstrate how groundwater modelling is applied to help understand contamination problems and how valuable the improved understanding is to decision-making and/or to remedial design.     

Analysis of radial movement of a confined aquifer due to well pumping and injection

Three aspects of radial motion of an aquifer solid matrix, driven by hydraulic forces due to well recharge and discharge, have been investigated mathematically. Firstly, the analytic solutions in the velocity and displacement fields were found using the definition of bulk mass flow, conservation of water and solid mass, the Darcy-Gersevanov law, and the drawdown of hydraulic head for unsteady flow. Secondly, the radial velocity and displacement of aquifer solid matrix were investigated with respect to time and location in response to three pumping-injection schemes (i.e., linear, nonlinear, and sinusoidal well flow rates). Aquifer movement was found to be more responsive to linear and nonlinear pumping rates than to constant pumpage. Aquifer movement in response to periodic well discharge and recharge was governed by an integral sinusoidal function. Finally, the potential risk of earth fissuring at a given location caused by tensile stress, in turn induced by well discharge-recharge activity, has been discussed using the analytic solution. The deformation compression and extension zones derived from analysis of the results indicated the possible occurrence of tensile stress that may cause earth fissures. Sample computations, using assumed parameters, provided a first-hand evaluation of the location of potential fissuring in relation to the well.     

Transmissivity estimation for highly heterogeneous aquifers: comparison of three methods applied to the Edwards Aquifer,Texas, USA

Obtaining reliable hydrological input parameters is a key challenge in groundwater modeling. Although many quantitative characterization techniques exist, experience applying these techniques to highly heterogeneous real-world aquifers is limited. Three geostatistical characterization techniques are applied to the Edwards Aquifer, a limestone aquifer in south-central Texas, USA, for the purposes of quantifying the performance in an 88,000-cell groundwater model. The first method is a simple kriging of existing hydraulic conductivity data developed primarily from single-well tests. The second method involves numerical upscaling to the grid-block scale, followed by cokriging the grid-block conductivity. In the third method, the results of the second method are used to establish the prior distribution for a Bayesian updating calculation. Results of kriging alone are biased towards low values and fail to reproduce hydraulic heads or spring flows. The upscaling/cokriging approach removes most of the systematic bias. The Bayesian update reduced the mean residual by more than a factor of 10, to 6 m, approximately 2.5% of the total head variation in the aquifer. This agreement demonstrates the utility of automatic calibration techniques based on formal statistical approaches and lends further support for using the Bayesian updating approach for highly heterogeneous aquifers.     

Aquifer overexploitation: what does it mean?

Groundwater overexploitation and aquifer overexploitation are terms that are becoming common in water-resources management. Hydrologists, managers and journalists use them when talking about stressed aquifers or some groundwater conflict. Overexploitation may be defined as the situation in which, for some years, average aquifer abstraction rate is greater than, or close to the average recharge rate. But rate and extent of recharge areas are often very uncertain. Besides, they may be modified by human activities and aquifer development. In practice, however, an aquifer is often considered as overexploited when some persistent negative results of aquifer development are felt or perceived, such as a continuous water-level drawdown, progressive water-quality deterioration, increase of abstraction cost, or ecological damage. But negative results do not necessarily imply that abstraction is greater than recharge. They may be simply due to well interferences and the long transient period that follow changes in the aquifer water balance. Groundwater storage is depleted to some extent during the transient period after abstraction is increased. Its duration depends on aquifer size, specific storage and permeability. Which level of "aquifer overexploitation" is advisable or bearable, depends on the detailed and updated consideration of aquifer-development effects and the measures implemented for correction. This should not be the result of applying general rules based on some indirect data. Monitoring, sound aquifer knowledge, and calculation or modelling of behaviour are needed in the framework of a set of objectives and policies. They should be established by a management institution, with the involvement of groundwater stakeholders, and take into account the environmental and social constraints. Aquifer overexploitation, which often is perceived to be associated with something ethically bad, is not necessarily detrimental if it is not permanent. It may be a step towards sustainable development. Actually, the term aquifer overexploitation is mostly a qualifier that intends to point to a concern about the evolution of the aquifer-flow system in some specific, restricted points of view, but without a precise hydrodynamic meaning. Implementing groundwater management and protection measures needs quantitative appraisal of aquifer evolution and effects based on detailed multidisciplinary studies, which have to be supported by reliable data. Electronic Publication     

Groundwater arsenic distribution in South-western Uruguay

This is the first specific information regarding arsenic distribution of groundwater in SW Uruguay. Twenty-eight wells were sampled on the aquifers of Mercedes, Raigón and Chuy in five localities. The pH, specific conductivity and temperature were determined in the field. The hydrochemical characterization (major and trace elements) was carried out by both inductively coupled plasma-optical emission spectrometry and inductively coupled plasma-mass spectrometry. The occurring arsenic concentrations exceed the recommended threshold for drinking water of the World Health Organization (10 μg/l of As) in 22 samples, with more than 50 μg/l of As in two cases. The median, minimum and maximum concentrations were 0.1, 16.9 and 58.0 μg/l of As, respectively. The studied aquifers present a horizontal and a vertical variation of the concentrations as a whole as well as individually. The highest values were observed in the Mercedes Aquifer in the areas near the Uruguay River.