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含水层的水文地质参数是进行地下水资源计算、地下水污染防控等所必需的基础数据,结合数值模拟技术进行含水层参数反演很有必要.按照1:5万水文地质调查规范在江汉平原仙桃市杨林尾镇复兴水厂不同含水层位开展抽水试验,包括深层含水层单孔抽水试验以及浅层含水层中群孔(2孔)抽水试验.对于单孔抽水试验,应用第1类越流系统井流理论进行参数反演;对于群孔抽水试验,推导了特定综合井函数,并利用特定标准曲线匹配法和直线图解法求解了含水层参数.随后利用FEFLOW软件建立了相应数值模型,拟合了含水层参数.结果表明:浅层含水层的渗透系数变化范围为21.66~54.00 m/d,贮水率变化范围为1.28×10-5~8.00×10-4 m-1;深层含水层渗透系数变化范围为1.27~7.00 m/d,贮水率变化范围为3.90×10-6~5.00×10-6 m-1.对于深层承压含水层而言,越流补给量较大.采用数值模拟方法结合抽水试验数据求参,综合考虑了含水层结构,拟合效果好,所得结果更加可靠. 相似文献
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弱透水层的渗透系数是区域地下水流系统划分和关键带水-土-生作用的重要参数.结合江汉平原关键带调查采集1:5万杨林尾-陆溪口图幅钻孔52组不同深度、不同岩性的原状土样,利用改进的渗透仪进行室内渗透实验,对粘性土样的渗透系数和粒度特征参数进行经验公式修正.发现研究区沉积物渗透系数与含水岩组埋深和岩性有关.浅层孔隙潜水含水岩组以粉质粘土、粘土为主,沉积环境稳定,渗透系数约10-9 m/s,变异系数为1.56;中深层承压含水岩组夹有多层粘土和粉砂,呈现多旋回分布的典型河湖交互作用的沉积环境,渗透系数为10-10~10-6 m/s,变异系数为2.04,变异性较大.利用有效孔隙比eu与黏粒含量P的显著二项式关系,修正预测粘性土渗透系数的太沙基经验公式,预测值与室内实测数据基本吻合,二者比值均小于10,验证了太沙基修正公式在河湖相平原区的适用性. 相似文献
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提出根据非稳定流抽水试验资料确定含水层参数的优化算法。该法不同于现有的配线法,其根据最小二乘法及0.618法原理进行优化计算,从而确定承压含水层的导水系数和弹性给水度及渗透系数等。优点是计算结果比较客观,计算精度比较高。给出了实例计算及与其他相比较的结果。 相似文献
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单井抽水试验是水文地质勘探中广泛实施的手段,其导水系数 K M 或渗透系数 K 值通常是从抽水结果的涌水量 Q 和井中水位降数据计算求得.但单井中水量的水位降深,多受井结构完善程度的制约,难以反映出井点处含水层真实的水位降.另外,在基岩含水层试验中,常以抽水井揭露所谓含水层的岩性岩层厚度作为含水层厚,这又给 K 值的确定带来一定的偏差.就日常工作中在对抽水成果整理方面所遇的一些问题提出见解,以共讨论 相似文献
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以天津市陆家嘴广场项目工程抽水试验数据为基础,为查明场地地基土渗透性和富水性,测定含水层的渗透系数、影响半径等水文地质参数,运用完整井非稳定流抽水试验资料的数学模型,利用迭代法、解析法和图解法计算含水层的渗透系数及影响半径。计算结果表明:试验及计算方法正确,所得结果可靠,所用方法可为类似工程含水层水文地质参数计算提供参考。 相似文献
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Theis模型、Dupuit模型等经典井流模型分析非均质含水层井流试验数据有一定的局限性,获取的参数不适合表征非均质含水层特性。而GRF模型可以获取含水层流动特性的数据。相比于Theis模型、Dupuit模型,GRF模型更能表征非均质含水层特性。以黄石东湖新村棋盘洲长江大桥的抽水试验数据为例,采用Theis模型和GRF模型计算含水层渗透系数,结合实际水文地质条件,对比分析不同方法计算的水文地质参数,并计算含水层水流维数和表观压力传导系数（Kf /Ssf）。结果表明:研究区含水层为细砂夹条带状黏土透镜体的非均质含水层,采用GRF模型计算结果更符合实际情况,渗透系数为 4.09×10?3cm/s;含水层水流维数为1.61,地下水为双线性流动状态,含水层对抽水试验的响应主要受黏土条带控制;观测井和抽水主井的Kf /Ssf呈非线性相关,进一步验证了含水层的非均质性。在非均质孔隙含水层中,应用多孔联合非稳定GRF井流试验方法不仅能确定水文地质参数,并且能丰富对含水层特性的认知。 相似文献
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Patsakron Assiri 《地下水科学与工程》2013,1(3):95-98
Phu tok Aquifer is the most productive water bearing rock in the Northeastern region of Thailand. Generally, well drilled in this aquifer yields approximately 20–50 m3/hr with some wells yield over 150 m3/hr. This aquifer characterized both unconfined and confined aquifer. Data collected from core sampling and TV bore hole show water bearing fractures in the fine grained massive sandstone intercalated with thin shale layers. These intermittently bedding plane fracture zones were found vertically at 60-65 and 95-110 m below ground surface. Three directions of vertically fractures were also found at 103-104 m in the test well with underlain densely sandstone until 120 m of depth. Wells drilled to 60-70 m fractures at the area where surface elevation between 150 and 170 m above mean sea level were artesian well with rising water about 1-3 m. Natural discharge rate from 2-5 inches of diameter casing is 5-10 m3/hr. Fractures at 90-110 m yield 150 m3/hr through 6 inch casing well with 5-6 m of risen water above the ground. It is found from pumping test of Phu Tok Aquifer that hydraulic conductivity of unconfined aquifer at shallower than 50 m is 0.005-17 m/d. Transmissivity and storage coefficient are 0.05-20 m2/d and 7×10-3-0.725 respectively. The confined aquifer at depth not exceed 90 m has hydraulic conductivity value of 0.2-10 m/d while transmissivity and storage coefficient are 3.19-150 m2/d and 1×10-10-1.6×10-2. Another confined aquifer at 90-120 m of depth have hydraulic conductivity value of 0.08-15 m/d and transmissivity and storage coefficient values of 1.7-178 m2/d and 4×10-7-4.5×10-3 respectively. 相似文献
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弱透水层是含水层系统的重要组成部分,其水文地质参数的准确获取一直以来都是研究难点,传统室内试验难以克服应力状态及环境变化对土层参数的影响,因此如何在原位状态下评价其水文地质参数有着重要意义。选取呼和浩特盆地某淤泥层为研究对象,基于抽水试验和溶质运移试验获得的多源数据,采用基于控制体积有限差分法的非结构化网格（Unstructured Grid）方法,建立三维地下水流-溶质运移耦合模型,对弱透水层水文地质参数进行反演。结果显示:模型计算的抽水井中水位和溶质浓度变化规律与实际观测数据能够较好拟合,模型识别出的抽水含水层渗透参数（4.8 m/d）与通过解析法计算得出的结果（4.17 m/d）相近,建立的数值模型符合实际水文地质条件;反演得到淤泥质弱透水层垂向渗透系数为1.2×10?4 m/d、储水率为1.0×10?5 m?1。基于多源数据的参数反演方法可为弱透水层参数研究提供借鉴。 相似文献
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Jean-Christophe Maréchal Jean-Michel Vouillamoz M. S. Mohan Kumar Benoit Dewandel 《Hydrogeology Journal》2010,18(8):1787-1796
A method to estimate aquifer thickness and hydraulic conductivity has been developed, consisting of multiple pumping tests. The method requires short-duration pumping cycles on an unconfined aquifer with significant seasonal water-table fluctuations. The interpretation of several pumping tests at a site in India under various initial conditions provides information on the change in hydrodynamic parameters in relation to the initial water-table level. The transmissivity linearly decreases compared with the initial water level, suggesting a homogeneous distribution of hydraulic conductivity with depth. The hydraulic conductivity is estimated from the slope of this linear relationship. The extrapolation of the relationship between transmissivity and water level provides an estimate of the aquifer thickness that is in good agreement with geophysical investigations. The hydraulically active part of the aquifer is located in both the shallow weathered and the underlying densely fractured zones of the crystalline basement. However, no significant relationship is found between the aquifer storage coefficient and initial water level. This new method contributes to filling the methodological gap between single pumping tests and hydraulic tomography, in providing information on the variation of the global transmissivity according to depth. It can be applied to any unconfined aquifer experiencing large seasonal water-table fluctuations and short pumping cycles. 相似文献
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Suman Kumar Aditya Sarkar Sachin Kumar Thakur Shashank Shekhar 《Journal of the Geological Society of India》2017,90(4):459-466
The Yamuna flood plains spread across the northern part of Indian subcontinent is home to millions of people. The ever-growing population in these plains make it difficult to sustain the demand of freshwater resources. However, the productive aquifers of flood plains could provide solution for these issues. In this context, it is necessary to understand the aquifer characteristics. Thus, the paper attempts to characterize the aquifer in Palla area of the flood plain using integrated approach. Besides, grain size analysis and site-litholog study, the nature of aquifer material was also ascertained from bulk mineralogy of the sediments using X-Ray Diffraction. The aquifer parameters were estimated with help of long duration pumping test data. Moreover, the effect of pumping on salinity variation and hydrochemical facies evolution was also examined. The sand dominant, unconfined aquifer was estimated to have horizontal hydraulic conductivity in the range of 25 m/day and vertical hydraulic conductivity of 6–7 m /day. While the specific yield of the aquifer was estimated in the range of 0.07–0.08. It is observed that under conducive active flood plain environment, the given sand mineralogy at the site does not allow salinity increase in groundwater even after more than a decade of groundwater pumping. In fact, over years, hydrochemical facies have evolved towards Bicarbonate type. These things put together make the active flood plain aquifer a sustainable groundwater resource. 相似文献
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The current study aimed to evaluate hydrogeologically the Nubian sandstone aquifer in El-Bahariya Oasis. It represents the main water-bearing horizon in the study area and consists of continental elastic sediments, mainly sandstone alternating with shale and clays. The general flow lines are directed from SW to NE direction, as detected from the constructed potentiometric head contour map. The piezometric surface reaches 149 m in El-Heiz area at the southern part, while it reaches 90 m at the northern, reflecting higher pressure head of the aquifer in the southern part. The map also illustrates that the southern part is considered as the most promising location for development. The structural elements play an important role in the deposition and distribution of the sedimentary succession of the Nubian sandstone sediments. Consequently, this sedimentary pattern affects the occurrences and movements of the groundwater within the aquifer system. Along the structurally high areas, in the study area, the piezometric head increases, while the reverse is recorded along the structurally low areas. The step-drawdown tests data were carried out by calculating the aquifer loss coefficient (B) and the well loss constant (C). The B values are smaller compared with C values, indicating that the aquifer under pressure has a behavior of leaky aquifer; therefore, it shows hydraulic connection with surrounding formation. The values of well efficiency range from 78.50% to 87.76%. Analysis of 12 pumping test data (constant discharge tests) was carried out in order to calculate the Nubian aquifer hydraulic parameters (transmissivity, hydraulic conductivity, and storage coefficient). The transmissivity values decrease from 3,045 m2/day in the southern part (El-Heiz area) to 236 m2/day in the northeastern part (El-Harra area). Accordingly, the aquifer classified as a high to moderate potentiality. Transmissivity contour map observes gradual increase of transmissivity values from the southern to northeastern direction. This may be due to the increase of shale or clay content in the concerned aquifer in that direction. The storage coefficient values range between 1.04 × 10?4 and 5.22 × 10?3, as obtained from the results of pumping test analysis, which ensure that the Nubian sandstone aquifer is classified as semi-confined to confined aquifer type. The S values show a decrease from southwest to northeast direction as detected from S-map. The hydraulic conductivity values vary from to 0.46 m/day in the northern part to 10.88 m/day in the southern part with an average of 5.67 m/day. According to the classification based on K values, the aquifer is mainly composed of coarse sand. 相似文献
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A hydrogeophysical model of the relationship between geoelectric and hydraulic parameters of anisotropic aquifers 总被引：1，自引：0，他引：1
An electrical resistivity method has been used to determine aquifer parameters in the Ganga-Yamuna interfluve in northern India. An existing relationship between the geoelectrical and hydraulic parameters has been modified for the case of an anisotropic aquifer. The hydrogeological framework in the upper part of the Ganga-Yamuna interfluve is evaluated by using existing relationships between hydraulic parameters and geoelectrical parameters for alluvial aquifers. On the basis of aquifer geometry, the area has been divided into two hydraulic units: the western Yamuna flood plain and the Ganga flood plain towards the east. The resistivity data collected in parts of the study area are first interpreted in terms of true resistivity and thicknesses of subsurface layers. The electrical parameters (resistivity and thicknesses) are subsequently correlated with the available pumping test data. Distinct correlations between transmissivity and modified transverse resistance are obtained for the two hydraulic units. A four-parameter model consisting of hydraulic conductivity, modified longitudinal resistivity, modified transverse resistance and hydraulic anisotropy is presented for the anisotropic aquifer underlain by conductive fine grained sediments. The model has been validated at a number of locations, where aquifer parameters are known from pumping test data. 相似文献
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弱透水层水力参数对基础工程设计、建设和地下水资源评价、地下水污染预测具有重要意义。现提出一种现场确定含水层系统中弱透水层水力参数的钻孔双管试验方法。利用麻花钻钻孔,到达地下水位线以下揭露到目的层位后布设外管,以起到护壁防止土层塌孔的作用。在外管内通过锤击的方式将内管嵌入到目的层中,使其下部管中有一定厚度的土样作为现场固定试验土柱。待内外管中地下水位稳定后迅速加高内管水头,并通过马里奥特瓶装置保持定水头。建立钻孔双管试验土柱的数学模型,推导了土柱顶底面单位面积流量随时间变化的解析解,将其无量纲化后作出标准曲线。作为该方法应用的实例,在长江下游三角洲苏锡常冲积平原的常州天宁区德安医院附近的空旷场地进行了专门的钻孔试验。确定了该地区的细砂质粉土和粉质黏土的渗透系数和贮水率分别为：K=1.66×10?6 m/s,?s =8.21×10?3 m?1;K=6.06×10?7 m/s,?s =2.26×10?3 m?1。结果表明,该方法对于现场确定弱透水层的水力参数有较好的适用性。 相似文献
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通过抽水试验,确定了拟建水源地——赵油坊的水文地质参数:平均导水系数878.27m2/d,弹性释水系数为6.85×10-4,压力传导系数为1.55×106m2/d,水跃值为3.44m;根据水文地质参数把水源地划分为6个单元。选用合理的计算模型,模拟不同开采条件下地下水水位下降情况,确定以24000m3/d的开采方案较为合理。 相似文献
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Evaluation of unconfined aquifer parameters from flow to partially penetrating wells in Tailan River basin, China 总被引：1，自引：1，他引：0
Emmanuel Kwame Appiah-Adjei Longcang Shu Kwaku Amaning Adjei Minjing Deng Xiaohui Wang 《Environmental Earth Sciences》2013,69(3):799-809
Effective evaluation, management and abstraction of groundwater resources of any aquifer require accurate and reliable estimates of its hydraulic parameters. This study, therefore, looks at the determination of hydraulic parameters of an unconfined aquifer using both analytical and numerical approaches. A long-duration pumping test data obtained from an unconfined aquifer system within the Tailan River basin in Xinjiang Autonomous Region in the northwest of China is used, in this study, to investigate the best method for estimating the parameters of the aquifer. The pumping test was conducted by pumping from a radial collector well and measuring the response in nine observation wells; all the wells used in the test were partially penetrating. Using two well-known tools, namely AquiferTest and MODFLOW, as an aid for the analytical and numerical approaches, respectively, the parameters of the aquifer were determined and their outputs compared. The estimated horizontal hydraulic conductivity, vertical hydraulic conductivity, and specific yield for the analytical approach are 38.1–50.30 m/day, 3.02–9.05 m/day and 0.204–0.339, respectively, while the corresponding numerical estimates are 20.50–35.24 m/day, 0.10–3.40 m/day, and 0.27–0.31, respectively. Comparing the two, the numerical estimates were found to be more representative of the aquifer in the study area since it simulated the groundwater flow conditions of the pumping test in the aquifer system better than the analytical solution. 相似文献