REFLECTIONS ON AMPLITUDES*

Modern seismic recording instruments allow precise measurements of the amplitude of reflected signals. Intuitively we would expect that this amplitude information could be used to increase our knowledge of the physical properties of the reflecting earth. The relevant factors defining the amplitude of a reflection signal are: spherical divergence, absorption, the reflection coefficient of the reflecting interface, the cumulative transmission loss at all interfaces above this, and the effect of multiple reflections. Of these factors, three—spherical divergence, the reflection coefficient and the transmission loss—are reasonably clear concepts (though the estimation of transmission loss from acoustic logs caused some difficulties in the hey-day of synthetic seismograms). Absorption still presents considerable problems of detail, but our understanding has increased significantly in recent years. The factor least well understood is undoubtedly the effect of multiple reflections. Multiple paths having an even number of bounces can have the effect of delaying, shaping and magnifying the pulse transmitted through a layered sequence. Simple demonstations of this phenomenon can be made using elementary thin plates, and these can be presented for various synthetic and real sequences of layers. Such demonstrations lead one to explore the relation between the spectrum of the transmitted pulse and the spectrum of the reflection coefficient series. If it were possible to isolate the amplitude and shape variations imposed by absorption within a layer, there would be a chance that this measure of absorption would be useful as a correlatable or diagnostic indication of rock properties. If it were possible to isolate the amplitude and shape variations imposed by multiple reflections, there would be a chance that this measure would be useful as an indication of cyclic sedimentation and of the dominant durations of the sedimentary cycles. However, the separation of these two effects constitutes a formidable challenge. The very difficulty of this separation suggests that it may be opportune to review the quantitative estimates of absorption made by field experiments.     

格尔木井水氡动态研究

通过对格尔木井水氡的正常动态、干扰动态和异常动态的分析,认为该井水氡多年正常动态平稳起伏,呈连续的“n”型变化,低点具有1.5～4年左右的变化周期;在排除干扰动态后,对两段明显的异常动态,引入同井动水位进行对比研究,认为两者之间存在一定的负相关关系.水氡正常动态的变化受控于动水位的变化,动水位受自流井补给区附近降雨、冰需融化等因素的影响.未发现令人信服的水氡前兆异常.     

乌鲁木齐台钻孔应变与水位相关性的初步研究

1999年 7月 11日乌鲁木齐台钻孔应变观测井的水位突然变化 ,通过计算该台应变与水位的相关系数和回归系数 ,研究了水位与应变的关系 ,认为利用此关系可以排除水位对观测值的影响     

REVIEW OF THE SYMPOSIUM ON THE DESIGN OF WATER RESOURCES PROJECTS WITH INADEQUATE DATA

Abstract

The use of a multivariate analysis approach to rationalize a piezometric network is not new. The utilization of its results for the distinction of zones with particular fluctuation patterns is a contribution which has fruitful outcomes. This technique was applied with success to the Erbil hydrogeological basin in Iraq where a network of only 15 wells out of an original network of 68 wells (monitored for about three years) is retained for the purpose of future monitoring of the yearly changes in the aquifer storage. This new network represents at least four fluctuation patterns of the piezometric surface in two different aquifers.     

泉州局一号井水位异常的调查与研究

对观测技术系统、降雨、区域应力场等干扰因素进行了排除,并调查观测井的周边环境及分析基础资料。结果表明,2011年底以来泉州局一号井水位突降为非前兆异常,造成的原因主要是周边基建干扰引起的。由于花岗岩地区特殊的岩石特征,即发育较多裂隙、微裂隙和解理,周边基建会破坏水井的承压性及封闭性,进而破坏地下水的动态平衡,建议在花岗岩地区选择水井时最好选择观测含水层与上一层非观测含水层间距较大的水井。     

天津高村井一次水位异常的调查与排除

针对天津高村井水位分钟值曲线在每日相对固定时间段出现的下降台阶错动型异常,对观测仪器、供电系统和观测环境进行了全面的调查与研究,结果表明水位异常系观测室南侧约10 m处的电镀作业间的高频直流设备漏电所导致。通过将漏电的高频直流逆变电源更换,有效排除了异常。提出在数字化水位观测中,不但要注意传统的诸如地下水超采等观测环境因素,还要重视可能对数字化水位仪有影响的电磁环境因素,补充、修订地下流体观测环境规范是十分必要的和紧迫的。     

城市供水系统抗震可靠性分析及对策研究

本文首先详细地论述了供水网络系统的可靠性分析方法，然后选取不同的供水系统模型进行了可靠和抗震对策分析，得到了有意义的结论。     

一次水汞观测高值异常的分析研究

2009年9月份之前,聊古一井水汞观测值在正常范围内波动,9月1日聊古1井水汞观测中出现高值异常,经过重复观测,水汞浓度是观测背景值的22倍.通过对流体测项其他敏感组分的分析和仪器运行情况的检查,没有发现异常.对观测环境现场调查发现,8月28日1支水银温度计不慎被打破,随后在不同环境下进行水汞对比观测分析,认为是水银温...     

天津地区井水位年变异常研究

近年来 ,中国地震预报学者开始关注井水位的年变异常及其中短期预测意义问题 ,但井水位年变异常判别采用动态图像的定性对比方法 ,表现出一定的随意性。针对这种现状 ,文中引进概率论与数理统计中的随机过程理论与时间序列分析技术 (盛骤等 ,1989) ,提出了“井水位动态年周期法”与“相对时段速率比较法” ,解决了井水位年变异常的定量识别方法 ,并应用到天津井网 2 1口井的观测数据 (1985年以来 )分析中 ,证明了该方法的可行性与有效性。分析结果表明 ,天津井网中有 7口井在首都圈邻区 4次中强 (MS≥ 5 .8)地震之前 ,表现出 17井次的井水位年变异常 ,且多在震前 1.5～6个月内出现 ,从而再次证明了井水位年变异常具有一定的中短期预测意义     

THE USE OF ENTROPY IN HYDROLOGY AND WATER RESOURCES

Since the development of the entropy theory by Shannon in the late 1940s and of the principle of maximum entropy (POME) by Jaynes in the late 1950s there has been a proliferation of applications of entropy in a wide spectrum of areas, including hydrological and environmental sciences. The real impetus to entropy-based hydrological modelling was provided by Amorocho and Espildora in 1972. A great variety of entropy applications in hydrology and water resources have since been reported, and new applications continue to unfold. This paper reviews the recent contributions on entropy applications in hydrology and water resources, discusses the usefulness and versatility of the entropy concept, and reflects on the strengths and limitations of this concept. The paper concludes with comments on its implications in developing countries. © 1997 by John Wiley & Sons, Ltd.     

THE UTILIZATION OF RIVER WATER RESOURCES IN ARID ZONES

ABSTRACT

Flood data were assembled for 168 Scottish basins containing 3071 station-years of record. Multiple regression techniques were used to produce equations for predicting mean annual flood from physiographic and climatological basin characteristics. Mean annual rainfall (SAAR) gave better results than measures of extreme rainfall (M52D and RSMD). Percentage area of lake storage (LOCH) was found to be a better predictor than fraction of the basin draining through a lake (LAKE). Apart from SAAR and LOCH, the recommended equation requires the basin area (AREA), stream frequency (STMFRQ) and an index of the soil type (SOIL). Measures of average basin slope (AVES) and main stream slope (S1085) were not statistically significant. The standard error of the estimate of the predicted mean annual flood is 0.147. The equation has a coefficient of determination, R², of 0.914 and appears robust over a wide range of basin types without requiring regionally derived multipliers or coefficients. No significant improvement in fit was acheived by ridge regression, Stein estimation or use of the influence function.