Basic concepts for the linear model of ground water level recession

Basic concepts are illustrated for the display of ground water level recession as a linear plot on a semilog graph, as first described by Rorabaugh. This exponential decay function can be achieved if there is a definable outflow boundary such as a lake or river and if water levels are expressed relative to the altitude of the boundary. The model can be used to estimate aquifer hydraulic diffusivity. Concepts are illustrated using three finite-difference simulations. One represents the ideal case as described by Rorabaugh, in which the altitude of the outflow boundary is uniform along its length. Another simulation includes a sloping boundary with simple geometry and demonstrates that the model can be used accurately. Based on this simulation, it appears that the ground water level must be expressed relative to the closest point on the outflow boundary. The third simulation includes a sloping boundary and complex boundary shape, and demonstrates departures from the linear model of recession and errors in the estimate of hydraulic diffusivity. Another cause of nonlinearity is the instability of the ground water head profile soon after a recharge event. The nature of these early-time departures will vary depending on the location of the water level observation site relative to the outflow boundary and the hydrologic divide of the ground water flow system.     

A program for evaluating dual-equilibrium desorption effects on remediation

Desorption is one of the most critical processes affecting the effectiveness of soil and ground water remediation. None of the currently adopted desorption models can accurately quantify desorption of low-hydrophobicity organic chemicals, and thus could potentially mislead remediation design and decision-making. A recently developed dual-equilibrium desorption (DED) model was found to be much more accurate in quantifying desorption. A screening-level transport model, DED-Transport, was developed to simulate the DED effect on behaviors of organic contaminant plumes during remediation. DED-Transport requires only simple parameters, but is applicable to many remediation scenarios. DED-Transport can be used as a decision-support tool in site remediation to more precisely predict the time required for cleanup.     

U.K.USAGE OF CHEMOMETRICS AND ARTIFICIAL INTELLIGENCE IN QSAR ANALYSIS

A survey of members of the U.K.QSAR Discussion Group has been made to determine the extent ofuse and development of chemometric and artificial intelligence(AI)methods in the analysis ofmultivariate quantitative structure-activity relationship(QSAR)data in the U.K.Chemometric methodswere found to be well established in both industrial and educational establishments and there wassignificant method development occurring.AI methods were not employed to any great extent and thegeneral level of interest in these techniques was low compared to chemometric methods.A requirementfor more education in multivariate statistical methods and regression methods was indicated.A need fora user-friendly,comprehensive,commercially available multivariate statistical package containingmultivariate stability testing and regression diagnostic methods was identified.     

苏联克里米亚强震预报是没有根据的

苏联最近流传的克里米亚地区将发生灾难性地震的“预报”是没有根据的。这是苏联电视台1990年3月2日的报道。电视台的记者之所以在这时采访苏联科学院地球物理研究所的     

地震与太阳活动

苏联国家水文气象委员会北极和南极科研所的瑟京斯基根据大量的统计资料研究了地球的地震活动与太阳和地磁活动以及与行星际介质状态的关系。为了进行分析,利用了从1904年至1977年底期间的年     

苏联格鲁吉亚地质-地球物理实验场开始工作

据塔斯社报道,一个供地质-地球物理综合实验用的实验场在格鲁吉亚加盟共和国(外高加索)已开始工作。实验场领导人季·加哈里亚对塔斯社记者说,“格鲁吉亚共和国的国土早已是全世界的地质学家、地理学家和气象学家公认的极好的自然实验室,在那里可以实地研究地球及其气候和景观的发育历史。在构造活动迄今仍很活跃的高加索存在着当今非