the changing relationship of hydrogeological parameters of dadianzi well-aquifer system

Hydrogeological parameter is an important index to characterize the hydrogeological properties of the aquifer, and has a clear physical basis and mechanism. Although the predecessors have made significant achievements in these areas, research is lacking on the changing law and relationship of the hydrogeological parameters of well-aquifer system. The digital water level and barometric pressure data of Dadianzi Well are used as the basis in this study. Based on the theories of elastic mechanics, rock mechanics and fluid mechanics, and using barometric pressure coefficient and tidal factor, the hydrogeological parameters in Dadianzi well-aquifer system in undrained conditions are studied. The corresponding water storage rate can also be obtained quantitatively. In addition, with the thickness of the aquifer, the pressure transmitting coefficient, the radius of the well and the frequency of the tidal wave, the permeability coefficient and transmissibility coefficient of well-aquifer system can be obtained, and the relationships between them are derived. The results show that: 1)There is an obvious power function relationship between porosity and solid skeleton volume compression coefficient, volume compression coefficient of water in aquifer, water storage rate, permeability coefficient and transmissibility coefficient. The volume compression coefficient of solid skeleton, water storage rate, permeability coefficient and transmissibility coefficient have a positive correlation with the porosity, the volume compression coefficient of water in aquifer decreases with increasing porosity. The volume compression coefficient of solid skeleton and water in aquifer can be well fitted to one of two quadratic polynomials. And the volume compression coefficient of water in aquifer is larger than the solid skeleton volume compression coefficient, water is more easily compressed. In addition, with the increase of water storage rate, the permeability coefficient and transmissibility coefficient also increase linearly; 2)Different from the traditional pumping test and indoor experiment, this paper uses the digital water level and other data, combined with the pressure coefficient and Venedikov tidal harmonic analysis results to access to the porosity, the volume compression coefficient of solid skeleton and water in aquifer medium, water storage rate, the permeability coefficient and the transmissibility coefficient. This method is simple and accurate.     

A single recovery type curve from Theis'' exact solution

The Theis type curve matching method and the Cooper-Jacob semilog method are commonly used for estimation of transmissivity and storage coefficient of infinite, homogeneous, isotropic, confined aquifers from drawdown data of a constant rate pumping test. Although these methods are based on drawdown data, they are often applied indiscriminately to analyze both drawdown and recovery data. Moreover, the limitations of drawdown type curve to analyze recovery data collected after short pumping times are not well understood by the practicing engineers. This often may result in an erroneous interpretation of such recovery data. In this paper, a novel but simple method is proposed to determine the storage coefficient as well as transmissivity from recovery data measured after the pumping period of an aquifer test. The method eliminates the dependence on pumping time effects and has the advantage of employing only one single recovery type curve. The method based on the conversion of residual drawdown to recovered drawdown (buildup) data plotted versus a new equivalent time (delta(t) x t(p)/t(p) + delta(t)). The method uses the recovery data in one observation point only, and does not need the initial water level h0, which may be unknown. The accuracy of the method is checked with three sets of field data. This method appears to be complementary to the Cooper-Jacob and Theis methods, as it provides values of both storage coefficient and transmissivity from recovery data, regardless of pumping duration.     

Unsteady flow to wells in layered and fissured aquifer systems

A solution has been developed for the calculation of drawdowns in leaky and confined multiaquifer systems, pumped by a well of constant discharge penetrating one or more of the aquifers. In contrast to earlier solutions the effects of elastic storage in separating and bounding aquitards have now completely been accounted for.

The computing technique is based on the numerical inversion of the Laplace transform. Two different methods are used and results are compared with an analytical solution. Both Stehfest's¹ algorithm and Schapery's² least squares method yield accurate results in a fraction of the computation time required for the analytical evaluation.

Selected sets of time-drawdown and distance-drawdown curves are plotted to illustrate multiple-aquifer well flow and to compare new solutions with results which were previously published. The analogy with flow is unconfined and fissured aquifers is demonstrated by multilayer models, representing multiple-porosity formations with linear and diffusive crossflow.     

Estimation of groundwater recharge in sandy till with two different methods using groundwater level fluctuations

Two methods for estimation of groundwater recharge, both based on groundwater level fluctuations, were applied in a moraine area in southeastern Sweden. The first method utilized a onedimensional soil water model which was tested against observed groundwater levels. The boundary conditions were defined by using standard meteorological data and submodels for precipitation, snow dynamics, interception, evapotranspiration and horizontal groundwater outflow. The second method directly transformed groundwater level fluctuations to equivalent amounts of water from a constructed recession curve and the specific yield concept. Conceptually the two methods could be characterized as inflow and response methods respectively.

A good fit between observed and simulated groundwater levels was obtained by the soil water modelling. The results were, however, shown to be rather insensitive to displacement in the water balance between evapotranspiration and groundwater outflow, giving a good fit for a simulated net groundwater recharge ranging between 134 and 197 mm. The results from the attempts to use groundwater level fluctuations directly were discouraging. Compared to the soil water simulations the results were unstable and quite different for different years. It was impossible to use a constant specific yield or even different specific yields depending on depth.

The conclusion was that the possibilities to use groundwater level data for quantitative water balance studies are limited under the studied climatical and hydrogeological conditions. The modelling effort clearly demonstrated the need for a better quantitative knowledge on soil properties if water balance information is to be deduced. The soil water model though, could be a valuable tool studying variations within and between different years as well as processes and single events.     

Numerical versus field studies of delayed yield in response to a moving water-table

As pumping proceeds in an unconfined aquifer the water-table is lowered and slowly drains out of the initially saturated material giving a delayed yield from storage. Although considerable work has been carried out on delayed yield, a definitive solution is still lacking. The unsaturated zone was treated here as a significant factor in delayed yield analysis. The one-dimensional unsaturated flow equation was solved numerically to simulate the flow in the zone located between successive water levels in the unconfined aquifer for the case with zero flux at the upper boundary. The moisture content distribution curve was integrated numerically to determine the amount of water drained with time. The study shows that the numerical results are in close agreement with the monitored field data, which implies the important role of the unsaturated zone and the reliability of the numerical simulation in describing this physical phenomenon. The results show that the relationship between the flux and time is sensibly in exponential form, which agrees with the general applicability of Boulton's assumption.     

河北兴济地电阻率干扰定量分析

结合电测深曲线、 岩性资料建立三维水平层状结构物理模型, 利用有限元法定量计算挖土水坑蓄水量和砖厂建设对兴济N60°W向地电阻率观测的影响。 研究结果显示, 测区内挖土水坑位于影响系数为负的区域, 夏季水位高时为低阻体, 冬季无水时为高阻体, 蓄水量的季节性变化导致N60°W向地电阻率具有冬低夏高的反向年变。 砖厂厂房由砖混结构改建为钢架结构, 位于测区影响系数为负的区域, 局部形成的低阻体引起N60°W测向地电阻率的趋势上升变化。     

Estimating the Horizontal Gradient in Heterogeneous, Unconfined Aquifers: Comparison of Three-Point Schemes

At least two approaches may be used to estimate the horizontal components of the hydraulic gradient based on measured heads from three observation points. First, the gradient may be estimated by passing a plane through the measured heads (h-method). Second, if the elevation of the base of the aquifer is known to be spatially constant, an estimate of the gradient may be obtained using the squares of the measured heads (h²- method). In the present study, these methods are examined in application to a heterogeneous system. Using Monte Carlo analysis, we demonstrate that the magnitude of the gradient estimated via the h-method involved significant bias, which increased when the distance separating the wells increased. In contrast, bias in the estimated magnitude of the gradient based on the h²-method decreased with increasing separation among the wells. Estimation variances for both the magnitude and orientation of the gradient also decreased with separation distance. The variance in the orientation was observed to remain relatively high, however, even at relatively large separations among the wells (e.g., 10 integral scales). These results are Interpreted as implying that the best estimate of the gradient for steady flow in an unconfined aquifer is derived from the h²- method with the wells separated by significant distances. These results also demonstrate the uncertainty inherent in estimating the gradient based on limited field data.     

利用地基观测对卫星观测电离层结构参数的定量验证研究

本文采用散点图、趋势线、相关系数及观测偏差等统计方法,利用COSMIC卫星和SPIDR提供的垂测仪观测的F₂层峰值电子密度数据,开展了综合统计及按季节、地方时和纬度的分类统计.统计结果显示:地基垂测仪与卫星观测到的相应的F₂层峰值电子密度数据具有很高的相关性,两者之间的相关系数高达0.95,相对偏差的平均值为-3.38%,标准差为19.54%.基于上述研究结果,提出了利用地面垂测仪观测数据验证卫星观测的电离层结构参数的方法,并给出了定性的判别依据和定量的判别标准,可在我国电磁监测试验卫星发射后,为F₂层峰值电子密度观测数据的真实性和有效性提供检验方法和保障.      

Factors influencing long range dependence in streamflow of European rivers

Investigating long range dependence of river flows, especially in connection with various climate and storage related factors, is important in order to improve stochastic models for long range dependence and in order to understand deterministic and stochastic variability in long‐term behaviour of streamflow. Long range dependence expressed by the Hurst coefficient H is estimated for 39 (deseasonalized) mean daily runoff time series in Europe of at least 59 years using five estimators (rescaled range, regression on periodogram, Whittle, aggregated variances, and least squares based on variance). All methods yield estimates of H > 0.5 for all data sets. The results from the different estimators are significantly positively correlated for all pairs of methods indicating consistency of the methods used. Correlations between H and various catchment attributes are also analysed. H is strongly positively correlated with catchment area. Apparently, increasing storage with catchment area translates into increasing long range dependence. H is also positively correlated with mean discharge and air temperature and negatively correlated with the mean specific discharge and the seasonality index (maximum Pardé coefficient). No significant correlation is found between the Hurst coefficient and the length of the analyzed time series. The correlations are interpreted in terms of snow processes and catchment wetness. Copyright © 2012 John Wiley & Sons, Ltd.     

Estimating longitudinal dispersion in rivers using Acoustic Doppler Current Profilers

The longitudinal dispersion coefficient (D) is an important parameter needed to describe the transport of solutes in rivers and streams. The dispersion coefficient is generally estimated from tracer studies but the method can be expensive and time consuming, especially for large rivers. A number of empirical relations are available to estimate the dispersion coefficient; however, these relations are known to produce estimates within an order of magnitude of the tracer value. The focus of this paper is on using the shear-flow dispersion theory to directly estimate the dispersion coefficient from velocity measurements obtained using an Acoustic Doppler Current Profiler (ADCP). Using tracer and hydrodynamic data collected within the same river reaches, we examined conditions under which the ADCP and tracer methods produced similar results. Since dead zones / transient storage (TS) are known to influence the dispersion coefficient, we assessed the relative importance of dead zones in different stream reaches using two tracer-based approaches: (1) TS modeling which explicitly accounts for dead zones and (2) the advection–dispersion equation (ADE) which does not have separate terms for dead zones. Dispersion coefficients based on the ADE tend to be relatively high as they describe some of the effects of dead zones as well. Results based on the ADCP method were found to be in good agreement with the ADE estimates indicating that storage zones play an important role in the estimated dispersion coefficients, especially at high flows. For the river sites examined in this paper, the tracer estimates of dispersion were close to the median values of the ADCP estimates obtained from multiple datasets within a reach. The ADCP method appears to be an excellent alternative to the traditional tracer-based method if care is taken to avoid spurious data and multiple datasets are used to compute a distance-weighted average or other appropriate measure that represents reach-averaged conditions.     

高阶晃动振型对LNG储罐地震响应的影响

为了研究高阶晃动振型对LNG储罐地震响应的影响,考虑高阶晃动振型,建立LNG储罐的简化力学模型,推导LNG储罐的运动控制方程,给出了LNG储罐的基底剪力、倾覆弯矩和储罐内液体晃动波高的表达式。以某16×10⁴ m³ LNG储罐为例,采用大型通用有限元分析软件ADINA System对其进行有限元模型分析,验证其修正模型的有效性,结果表明:高阶晃动振型对基底剪力和倾覆弯矩几乎无影响,但对晃动波高影响显著,尤其是长周期地震动作用下,并且考虑高阶晃动振型的晃动波高存在延时效应。提出的简化力学模型修正公式与有限元分析结果吻合较好,可以准确地预测LNG储罐地震响应。     

利用GRACE卫星重力数据监测关中地区地下水储量变化

关中地区作为一带一路重要的工农业发达地区之一,开展针对该地区地下水储量变化的监测和分析工作对揭示地下水储量变化特征与经济社会发展具有重要现实意义.本文基于2003—2014年GRACE卫星重力场模型数据,采用组合滤波及单一尺度因子方法反演了关中地区陆地水储量变化,扣除GLDAS地表水平均结果,对关中地区地下水储量变化进行了监测分析.将陆地水储量变化与GLDAS进行相关性分析,将地下水储量变化与WGHM地下水模型及实测地下水位结果进行对比分析.研究结果表明：①关中地区陆地水变化与GLDAS模型结果具有较强的相关性,相关系数多数大于0.7,其中与模型平均结果的相关系数可达0.8.② 2003—2008年关中地区地下水呈正增长趋势,增加速率为0.25 cm·a^-1,与同期实测数据变化趋势一致;但2003—2013年地下水存在长期亏损,亏损速率为-0.37 cm·a^-1等效水高,这与同时期WGHM估算结果-0.35 cm·a^-1十分吻合.③关中地区地下水存在明显的年变化特征,在2003—2014年期间地下水减少速率为-0.44 cm·a^-1,与该地区降雨量有较好的一致性,在降雨偏少的2008、2012和2013年,地下水也显著减少.     

由地震背景噪声提取介质衰减:衰减介质中的空间相干表示

传统基于地震背景噪声互相关的层析成像技术,主要利用了互相关函数的相位信息,即利用走时来反演地球介质的速度和各向异性特征.最近,开始有研究人员利用互相关函数的振幅信息提取介质的衰减.主要是将二维弹性情形下,互相关函数正比于第一类零阶贝塞尔函数J_0(k_0r)这一结论,通过引入指数衰减系数,直接推广到衰减介质情形,令衰减介质中背景噪声互相关函数类比于J_0(k_0r)·e~(-α(ω)r),以此来反演介质的衰减系数α.然而,在衰减介质中,互相关受源的方位平均的影响,这种简单的推广,可能无法提取可靠的衰减系数.本文基于平面波的叠加模型,研究不同的互相关定义和坐标选择下,衰减介质中两点间互相关函数的理论表达式.结果表明,在平面波叠加模型下,互相关函数的表达形式随着坐标原点的选择,并因而随着源分布的变化而变化,对不同的归一化因子,表达式也不尽相同.利用J_0(k_0r)·e~(-α(ω)r)的形式拟合背景噪声的观测数据得到的衰减比实际值偏小.     

用于区域重力场定量解释的多尺度刻痕分析方法

本文介绍一个把小波多尺度分析、表面刻痕分析以及位场频率域解释理论和反演方法结合起来的数据处理、反演解释和信息提取的方法系统.这一方法系统简称为区域重力场多尺度刻痕分析方法,应用于刻画地壳分层的三维密度结构、地壳变形带分布和构造单元分区.多尺度刻痕分析包含频率域重力场场源分层、重力场小波变换多尺度分解、场源分层深度及密度扰动反演、分层刻痕分析和构造边界定位四个子系统.文中扼要地介绍这四个子系统基本原理、方法技术及应用效果.从地球物理探测到大地构造学发现,是一个多学科综合研究的探索过程.要取得重大研究成果,必须研发和组合来自不同学科的多个新方法技术,使多学科综合研究有宽厚的理论支撑.本文介绍的四个子系统组合的理论支撑分别来自应用数学、地球物理学和信息科学.     

井水位随气压变化之解析解

气压作用下, 井-含水层系统中地下水流是一类流体力学问题。 本文应用井壁水流通量边界条件和气压作用下井壁内外水(孔)压平衡条件, 提出了一个井水位随气压变化的解析公式。 解析式表明, 气压系数随时段长度增加而增大, 并趋于气压常数; 气压系数随时段长度的变化只依赖于导水系数与井半径平方的比值(T/r²_w), 而与气压变化过程无关; 气压常数只与含水层的一维荷载效率(B)有关, 而与导水系数和井半径无关。 解析解所反映的气压系数与时段长度的关系, 与南溪井实测序列数据分析结果具有很好的一致性。 根据气压系数随时段长度变化过程, 提出了一个参数估计方法, 应用于估计南溪井含水层气压常数和导水系数, 并对本文提出的参数估计方法进行了讨论。     

河北省沙城地倾斜潮汐波的调和分析

用别尔采夫方法对河北省沙城1972年3月份的地倾斜观测资资进行了调和分析,得出了三个主要半日波M₂、S₂、N₂和两个主要日波K₁、O₁的弹性系数γ和位相差△δ。其中半日波M₂、S₂的结果比较好。M₂、S₂波的弹性系数γ分别为:南北向0.84、0.86;东西向0.81、0.77。即东西向的弹性系数略小于南北向的弹性系数。     

井水位的“记忆”滞后效应

观测资料表明,井水位对信息响应存在的“记忆”滞后现象,它与一般的位相滞后不同,在鲁２９井现场试验也证明了井水位对井吕空气压力变化的响应存在的“记忆”滞后现象。利用水平层状承压含水层模式,从理论上解释了井水位对井口空气压力变化响应“记忆”滞后现象,认为这种现象与水井含水层的导水系数有关,含水层导不系数越小,这种现象越明显,用一般多元回归方法无法较好地扣除井水位中“记忆”滞后影响,作给出了一种可以扣     

Application of groundwater hydraulics to a basaltic water-table aquifer

Analysis of pump-test data of open wells in a basaltic water-table aquifer is made with methods based on both equilibrium and non-equilibrium formulae. The study has indicated that the Thiem's equilibrium formula and the ratio method of Narasimhan appear to be more suitable as compared with Jacob's and Chow's methods. Of the two, Narasimhan's ratio method, which does not require the graphical procedure, is more reliable than the Thiem's method since the latter involves an assumption of the value for the radius of influence. From the value of T (coefficient of transmissibility) obtained by Narasimhan's method it is also possible to calculate the value of the radius of influence by Thiem's method, which can be used in determining the required spacing between wells in the basaltic terrain in order to avoid mutual interference.     

Development of a short-term river flood forecasting method for snowmelt driven floods based on wavelet and cross-wavelet analysis

In this study, a new method of stand-alone short-term spring snowmelt river flood forecasting was developed based on wavelet and cross-wavelet analysis. Wavelet and cross-wavelet analysis were used to decompose flow and meteorological time series data and to develop wavelet based constituent components which were then used to forecast floods 1, 2, and 6 days ahead. The newly developed wavelet forecasting method (WT) was compared to multiple linear regression analysis (MLR), autoregressive integrated moving average analysis (ARIMA), and artificial neural network analysis (ANN) for forecasting daily stream flows with lead-times equal to 1, 2, and 6 days. This comparison was done using data from the Rideau River watershed in Ontario, Canada. Numerical analysis was performed on daily maximum stream flow data from the Rideau River station and on meteorological data (rainfall, snowfall, and snow on ground) from the Ottawa Airport weather station. Data from 1970 to 1997 were used to train the models while data from 1998 to 2001 were used to test the models. The most significant finding of this research was that it was demonstrated that the proposed wavelet based forecasting method can be used with great accuracy as a stand-alone forecasting method for 1 and 2 days lead-time river flood forecasting, assuming that there are no significant trends in the amplitude for the same Julian day year-to-year, and that there is a relatively stable phase shift between the flow and meteorological time series. The best forecasting model for 1 day lead-time was a wavelet analysis model. In testing, it had the lowest RMSE value (13.8229), the highest R² value (0.9753), and the highest EI value (0.9744). The best forecasting model for 2 days lead-time was also a wavelet analysis model. In testing, it had the lowest RMSE value (31.7985), the highest R² value (0.8461), and the second highest EI value (0.8410). It was also shown that the proposed wavelet based forecasting method is not particularly accurate for longer lead-time forecasting such as 6 days, with the ANN method providing more accurate results. The best forecasting model for 6 days lead-time was an ANN model, with the wavelet model not performing as well. In testing, the wavelet model had an RMSE of 57.6917, an R² of 0.4835, and an EI of 0.4366.     

对东明深井注水恢复试验的解释

本文介绍了山东东明井的概况。1987年3月在该井进行了注水恢复试验,将该井含水层理想化为一无限水平承压含水层,根据H.H.Cooper等理论,对这次试验结果进行了处理,求出了东明井含水层的导水系数为8.7×10~9(m~2/s),这比一般含水层低得多。讨论了该井无“微动态”变化的原因,在于其含水层渗透性太差。 注水恢复试验方法为确定水井含水层的导水系数给出了一种简易可行的方法。有了这个系数,对井水位变化的分析提供了一种有用的参数。