The Role of Observer Variation in Determining Rosgen Stream Types in Northeastern Oregon Mountain Streams1

Abstract: Consistency in determining Rosgen stream types was evaluated in 12 streams within the John Day Basin, northeastern Oregon. The Rosgen classification system is commonly used in the western United States and is based on the measurement of five stream attributes: entrenchment ratio, width‐to‐depth ratio, sinuosity, slope, and substrate size. Streams were classified from measurements made by three monitoring groups, with each group fielding multiple crews that conducted two to three independent surveys of each stream. In only four streams (33%) did measurements from all crews in all monitoring groups yield the same stream type. Most differences found among field crews and monitoring groups could be attributed to differences in estimates of the entrenchment ratio. Differences in entrenchment ratio were likely due to small discrepancies in determination of maximum bankfull depth, leading to potentially large differences in determination of Rosgen’s flood‐prone width and consequent values of entrenchment. The result was considerable measurement variability among crews within a monitoring group, and because entrenchment ratio is the first discriminator in the Rosgen classification, differences in the assessment of this value often resulted in different determination of primary stream types. In contrast, we found that consistently evaluated attributes, such as channel slope, rarely resulted in any differences in classification. We also found that the Rosgen method can yield nonunique solutions (multiple channel types), with no clear guidance for resolving these situations, and we found that some assigned stream types did not match the appearance of the evaluated stream. Based on these observations we caution the use of Rosgen stream classes for communicating conditions of a single stream or as strata when analyzing many streams due to the reliance of the Rosgen approach on bankfull estimates which are inherently uncertain.     

石太客运专线安全保障体系的探讨

针对石太客运专线自身的特点,借鉴国外高速铁路安全运行的经验,运用系统工程相关理论,阐述了石太客运专线安全保障体系的安全因素和基本框架的主要内容,并提出了相关的建议.     

DQO- PRO软件在优化环境监测方案中的应用

介绍了美国开发的一个环境监测方案优化辅助软件———DQO -PRO ,阐述了其开发背景、设计思想及具体使用方法。该软件可以从互联网上免费下载 ,可以供我国环境监测人员在工作中借鉴     

水质自动监测系统运行过程中的质量保证和质量控制

以常州市武进水质自动监测站的工作为例,根据水质自动监测系统的技术特点,提出健全各项规章制度,培训技术人员,建立质量保证体系和自动监测系统运行的质量控制方法,以保证水质自动监测系统的正常运行。     

浅谈美国环境监测质量保证与质量控制

介绍了美国环境监测质量保证(QA)/质量控制(QC)体系及其基本程序,着重对其监测项目QA/QC规划做了详细介绍。目的使其对我国环境监测QA/QC体系的完善起到一定的借鉴和指导作用。     

近岸海域水质自动监测质量保证和质量控制

根据实际工作经验,阐述了近岸海域水质自动监测系统运行过程中的质量保证与质量控制措施,包括建立规章制度、实验室条件、设备维护和校准、数据检查和审核、记录等方面的要求,通过实例介绍了设备维护和校准周期的确定、设备维护效果的影响和数据有效性的判别等,为近岸海域连续自动监测系统的有效管理提供依据。     

A PRACTICAL MODEL INTEGRATING QUALITY ASSURANCE INTO ENVIRONMENTAL MONITORING1

ABSTRACT: A model of comprehensive environmental monitoring process with integral quality assurance is presented. This model views the monitoring process as iterative cycles of a series of elements: design, plan, protocols, preparation, field liaison, sample collection, sample handling, laboratory analysis, data transmission, data validation, data approval, data provision, statistical analysis, and reporting. Quality assurance is linked to each element, not just to laboratory analysis. The program of quality assurance ensures that environmental monitoring data are compatible with the project goals, are comparable between various sampling agencies, and maintain a high degree of scientific credibility. The key characteristics of the overall quality assurance process are detailed documentation, timely resolution of problems, regular reporting, and routine independent audits.     

Assessment of Quality for Middle Level and High School Student‐Generated Water Quality Data

Student scientists have analyzed groundwater used for drinking water in rural areas to understand groundwater quality. This was part of a greater effort to understand risks to drinking water. The data produced by middle level and high school students have not been accepted by experts because of concerns about method and student accuracy. We assessed the inherent errors associated with method accuracy, student precision, and sample variability to establish bounds for attainable trueness in water analyses. Analytical test kits and probes were evaluated for the determination of pH, conductivity, chloride, hardness, iron, total soluble metals, and nitrate. In terms of precision, all methods met or exceeded design specifications. Method trueness was variable and in general ranged from good to poor depending on method. A gage reproducibility and repeatability analysis of instrumental methods (pH and conductivity) partitioned the variances into student error (12‐46%), instrumental error (8‐21%), and random error (45‐68%). Overall, student‐generated data met some of the quality objectives consistent with the method limitations. Some methods exhibited a systematic bias and data adjustment may be necessary. Given good management of the student analyst process, it is possible to make precise and accurate measurements consistent with the methods specifications.     

通用航空公司安全运行保障能力未确知测度分析

通用航空公司安全运行保障能力是通用航空公司可持续健康发展的前提条件,是实现民航"两翼齐飞"的重要基石。根据通用航空公司安全运行保障能力较为低下的现状,以通用航空公司为例,基于日常运行状况和特点,结合现场调研结果,从人员、机械设备、环境、管理4方面提出了通用航空公司安全运行保障能力指标体系,鉴于其运行具有不确定性、模糊性和复杂性等特点,构建通用航空公司安全运行保障能力未确知测度分析模型,对其安全运行保障能力的水平进行评估,并与公司评估小组的评估结果进行对比,发现:模型计算所得到的安全运行保障能力等级与实际情况相符合,确定了通用航空公司今后应重点加强专业化人员培养、设备及时更新和设备维护等方面的工作。