Using recovery data to extend the effective duration of pumping tests

Collection of water-level recovery data is a common practice for pumping tests. The resulting data can provide some of the most useful information from the tests, but are rarely used to their full value. van der Kamp (1989) proposed a general method that uses recovery data to extend the effective duration of pumping. The method is straightforward to implement and applicable for simple or complex hydrogeologic settings. The only assumption invoked is that the response remains linear such that the principle of superposition can be applied. No other assumptions about the properties of the aquifer are required. The method can greatly increase the value of pumping tests by extending the effective duration of the tests for as long as significant residual drawdowns are observed.     

NAPL source zone depletion model and its application to railroad-tank-car spills

We developed a new semi-analytical source zone depletion model (SZDM) for multicomponent light nonaqueous phase liquids (LNAPLs) and incorporated this into an existing screening model for estimating cleanup times for chemical spills from railroad tank cars that previously considered only single-component LNAPLs. Results from the SZDM compare favorably to those from a three-dimensional numerical model, and from another semi-analytical model that does not consider source zone depletion. The model was used to evaluate groundwater contamination and cleanup times for four complex mixtures of concern in the railroad industry. Among the petroleum hydrocarbon mixtures considered, the cleanup time of diesel fuel was much longer than E95, gasoline, and crude oil. This is mainly due to the high fraction of low solubility components in diesel fuel. The results demonstrate that the updated screening model with the newly developed SZDM is computationally efficient, and provides valuable comparisons of cleanup times that can be used in assessing the health and financial risk associated with chemical mixture spills from railroad-tank-car accidents.     

Contaminant plume classification system based on mass discharge

Estimation of mass discharge has become an increasingly valuable analysis technique at sites with contaminated groundwater plumes. We propose a simple plume magnitude classification system based on mass discharge comprised of 10 separate magnitude categories, such as a "Mag 7 plume." This system can be a useful tool for scientists, engineers, regulators, and stakeholders to better communicate site conceptual models, prioritize sites, evaluate plumes both spatially and temporally, and determine potential impacts.     

震源复杂性的常规估计方法：用于1992年10月18日哥伦比亚地震

本文介绍两种适用于远震记录的方法，来表征地震事件的时间进程。叠加由大的区域台阵记到的短周期信号可获得震源高频辐射的稳定估计；而对经验格林函进行反褶积则可获得适用于分析破裂复杂和破裂时空间尺度的可靠的宽带震源时间函数。     

油气地表地球化学勘查的单参数和多参数方法

自从30年代G·Iaubmeyer和V.A.Soko(?)ov第一次提出油气地表化学勘查以来,油气化探的发展几经盛衰,现在又进入了一个全面发展时期。近年来,国内外利用化探方法,找到了一大批油气藏,特别是地震方法难以发现的低缓圈闭和地层圈闭的油气藏,引起了整个石油勘查界的极大兴趣和关注。但是,由于油气地表地球化学信息较金属矿弱得很,而且受近地表的土壤性质和地表的气候变化及微生物活动等因素的干扰,地表地球化学晕的形状和强度变化多端,这就给地表地球化学资料的正确解释,推断和对比带来了严重困难。针对上述情况,谢学锦教授在1986年就提出“使用多参数的化探方法,将所获得的各种信息互相验证,互相增强,从而增加解释推断的可靠性”本文就是在这样的思想启迪下,探讨一下单参数和多参数地表地球化学方法,提高地表地球化学勘查对油气藏的识别力,以达到正确推断下伏油气藏存在的目的。     

太平洋板块相对欧亚板块的运动及其与欧亚板块东缘新生代扩张的潜在关系

太平洋板块相对欧亚板块的运动及其与欧亚板块东缘新生代扩张的潜在关系Ｃ．Ｊ．Ｎｏｒｔｈｒｕｐ等Ｍｏｌｎａｒ和Ｔａｐｐｏｎｎｉｅｒ（１９７５，１９７７）首次提出亚洲的许多构造特征与印度一欧亚板块碰撞带中的地壳碎块侧向消亡有关．他们认为欧亚的东缘为一自由边...     

Geochemical quantification of semiarid mountain recharge

Analysis of a typical semiarid mountain system recharge (MSR) setting demonstrates that geochemical tracers help resolve the location, rate, and seasonality of recharge as well as ground water flowpaths and residence times. MSR is defined as the recharge at the mountain front that dominates many semiarid basins plus the often-overlooked recharge through the mountain block that may be a significant ground water resource; thus, geochemical measurements that integrate signals from all flowpaths are advantageous. Ground water fluxes determined from carbon-14 ((14)C) age gradients imply MSR rates between 2 x 10(6) and 9 x 10(6) m(3)/year in the Upper San Pedro Basin, Arizona, USA. This estimated range is within an order of magnitude of, but lower than, prior independent estimates. Stable isotopic signatures indicate that MSR has a 65% +/- 25% contribution from winter precipitation and a 35% +/- 25% contribution from summer precipitation. Chloride and stable isotope results confirm that transpiration is the dominant component of evapotranspiration (ET) in the basin with typical loss of more than 90% of precipitation-less runoff to ET. Such geochemical constraints can be used to further refine hydrogeologic models in similar high-elevation relief basins and can provide practical first estimates of MSR rates for basins lacking extensive prior hydrogeologic measurements.