BUILDUP,WASHOFF, AND EVENT MEAN CONCENTRATIONS1

ABSTRACT: Most watershed water quality simulation models require the user to specify pollutant buildup and washoff rate parameters for pollutants, by land use. Buildup and washoff rates are difficult to measure directly, and only limited guidance and few observed data are available from the literature. Many studies, however, report storm event mean concentrations (EMCs). These EMCs must arise as a result of the buildup and washoff processes, but typically represent the net contribution from a variety of pervious and impervious surfaces. This paper explores the relationship between EMCs and buildup/washoff parameters. An assumption of the mathematical form of the buildup/washoff relationship gives an algebraic expression for the EMC consistent with model assumptions. This yields techniques to separate observed EMCs into contributions from different land uses and from pervious and impervious surfaces. Given this relationship, numerical optimization may be used to estimate site specific values of buildup and washoff parameters from observed storm EMCs for use in modeling. Use of this approach helps ensure that model parameters are consistent with observed data, providing a rational starting point for final model calibration. Several site examples demonstrate use of the method.     

USE OF STAGE DATA TO CHARACTERIZE HYDROLOGIC CONDITIONS IN AN URBANIZING ENVIRONMENT1

ABSTRACT: This paper presents the results of a study on the use of continuous stage data to describe the relation between urban development and three aspects of hydrologic condition that are thought to influence stream ecosystems—overall stage variability, stream flashiness, and the duration of extreme‐stage conditions. This relation is examined using data from more than 70 watersheds in three contrasting environmental settings—the humid Northeast (the metropolitan Boston, Massachusetts, area); the very humid Southeast (the metropolitan Birmingham, Alabama, area); and the semiarid West (the metropolitan Salt Lake City, Utah, area). Results from the Birmingham and Boston studies provide evidence linking increased urbanization with stream flashiness. Fragmentation of developed land cover patches appears to ameliorate the effects of urbanization on overall variability and flashiness. There was less success in relating urbanization and streamflow conditions in the Salt Lake City study. A related investigation of six North Carolina sites with long term discharge and stage data indicated that hydrologic condition metrics developed using continuous stage data are comparable to flow based metrics, particularly for stream flashiness measures.     

THE MISUSE OF HYDROLOGIC UNIT MAPS FOR EXTRAPOLATION,REPORTING, AND ECOSYSTEM MANAGEMENT1

ABSTRACT: The use of watersheds to conduct research on land/water relationships has expanded recently to include both extrapolation and reporting of water resource information and ecosystem management. More often than not, hydrologic units (HUs) are used for these purposes, with the implication that hydrologic units are synonymous with watersheds. Whereas true topographic watersheds are areas within which apparent surface water drains to a particular point, generally only 45 percent of all hydrologic units, regardless of their hierarchical level, meet this definition. Because the area contributing to the downstream point in many hydrologic units extends far beyond the unit boundaries, use of the hydrologic unit framework to show regional and national patterns of water quality and other environmental resources can result in incorrect and misleading illustrations. In this paper, the implications of this misuse are demonstrated using four adjacent HUs in central Texas. A more effective way of showing regional patterns in environmental resources is by using data from true watersheds representative of different ecological regions containing particular mosaics of geographical characteristics affecting differences in ecosystems and water quality.     

事故前人因失误研究

在安全评价中，人因失误特别是事故后人因失误越来越受到重视；但相对而言，事故前人因失误没有引起足够的重视。本通过对大量核电厂安全分析报告和运行事件报告的考察，系统地阐述了事故前人因失误对系统安全的显影响，并在此基础上，归纳出在核电站开展事故前人因(失误)分析的程序。该程序主要包括系统熟悉，定性分析，筛选，定量计算，与故障树的集成，敏感性分析与不确定性分析，形成分析档等几个步骤。     

高速铁路轨道的安全管理

高速铁路的轨道结构要求具有高平顺性。为使轨道结构的平顺性持久、稳定 ,需要在设计、施工、管理各个环节进行严格控制。国外高速铁路的运营经验表明 ,轨道的安全管理在实现高速行车时 ,起着巨大的技术保障作用。笔者在分析高速铁路轨道结构的平顺性特征基础上 ,讨论了轨道不平顺管理、列车振动加速度管理、钢轨踏面及伤损管理、无缝线路管理等方面的问题 ,并提出了改进新思路 ,即应建立异常情况下的处理机制。     

论动态安全评价

指出了静态安全评价存在的问题 ,提出了动态安全评价的概念、思路、方法和步骤 ,给出了动态的组合危险值、工程量危险值、事故损失率和安全指数的表达式。动态安全评价可以克服静态安全评价的不足 ,还能发挥安全评价对风险预测、事故预防 ,提高安全管理水平的重要作用。     

商厦火灾危险性评价研究

商厦火灾是火灾中危害性较大的灾害之一，常常造成人员的大量伤亡和巨大的财产损失。商厦火灾危险性评价是一个减少火灾危险性的可行方法。在基于影响商厦火灾危险性因素之上，讨论了评价指标体系的建立及量化和权重的处理方法，然后应用模糊数学理论建立了评价商厦火灾的模糊评价模型，对商厦火灾的预防与商厦消防管理具有指导意义。     

如何做好职业安全健康管理体系内审工作

作为职业安全健康管理体系中第2层次的监督机制，内部审核与绩效测量和监测、管理评审及事故、事件、不符合、纠正和预防措施共同组成体系完整的监督保障机制。通过介绍内审的目的、内容、特点、原则、实施过程等方面内容，指出做好内审工作需关注的若干问题。     

我厂安全管理的几点经验

神州煤电焦化股份公司焦化厂调整思路，探索出一套“以人为本，重在落实”的基层车间管理办法，通过实践，证明该方法是行之有效的，使该厂形成了互相监督、互相制约的良好安全氛围。     

市场经济条件下企业的安全管理

随着社会主义市场经济的建立和发展，要求企业更规范、更有效、更安全地进行生产。目前，我国的安全生产工作还面临着十分严峻的形势。所以，加强企业的安全管理，提高安全生产水平是大势所趋。分析了当前企业安全管理工作中面临的问题，对如何强化企业的安全管理提出了一些意见和建议。