PREDICTION OF MEAN ANNUAL FLOWS IN THE FRASER RIVER CATCHMENT,BRITISH COLUMBIA1

ABSTRACT: A method of predicting annual flows is presented and is applied to the Fraser River catchment. Statistical tests show the annual flow records to be stationary and aerially independent and can be adequately approximated by Gaussian distributions. Estimates are made of the Gaussian parameters for each subbasin. The spatial variations of these parameters are described by third order trend surfaces. The fitted surfaces can then be used to predict parameters of ungaged basins using the latitude and longitude of the basin centroids. The predicted parametric values are substituted into the Gaussian distribution to generate flows of various return periods.     

中国内陆自然环境的干旱化与未来趋势

根据中国内陆陕西、甘肃部分地区５０９ａ旱涝资料和主要测站气象、水文实测数据,应用Ｗｏｒｄ９７图形处理系统,证明在５２６ａ序列中目前处在１１ａ、５０ａ滑动的干旱期。近４６ａ气温上升了０．３℃,年降水减少了８０ｍｍ,径流量减少了０．７８％,出现了明显的干旱化,环境变化趋势不容乐观。     

NONPARAMETRIC STATISTICAL METHODS IN URBAN HYDROLOGIC RESEARCH1

ABSTRACT. In urban hydrologic studies, it is often necessary to determine the effect of changes in urban land use patterns on such runoff characteristics as flood peaks and flow volumes. Nonparametric statistical methods have certain properties that make them a valuable tool for detecting hydrologic change caused by a treatment, such as urbanization, that changes watershed over a period of time. As many hydrologists do not have a working familiarity with nonparametric methods, a number of them are used for illustrative purposes to analyze the effect of urbanization on 24 years of annual flood peaks for a Louisville, Kentucky, watershed. In the example, urbanization was found to increase the central tendency, but not the dispersion of the peaks. Peak flows modeled by holding watershed parameters constant were also found to be increasing because of an upward trend in precipitation. By following the numerical examples in the paper and looking up test statistics in referenced sources, the reader can easily apply these methods to other situations.     

近10年安徽省的各类灾害及发展趋势

安徽是各种灾害频发的省份之一。由于所处的特殊地理位置，旱、涝等气象灾害严重；生物、地质、环境和人为事故灾害等也经常发生并有加重趋势。本文回顾了20世纪90年代安徽上述五类灾害发生的情况，分析了这些灾害的相互关系，并对安徽未来l0年灾害发展趋势作出了宏观预测。     

RELATING TRENDS OF PRINCIPAL COMPONENTS TO TRENDS OF WATER-QUALITY CONSTITUENTS1

ABSTRACT: The seasonal Kendall test is used for detecting water-quality trend or lack of trend for monthly data of 15 water-quality constituents at 15 sampling stations in the Arkansas River, the Neosho River, and the Verdigris River basins. Trends of individual constituents and the trends of the first four principal components for the correlation matrix of water-quality data at each station are determined, and the relationships between the trends of constituents and the trends of principal components are established. Using the principal components not only reduces the high dimensionality of the original data to a few principal components, but also presents an overall picture of water-quality trend of these river basins.     

TRENDS IN FRESHWATER INFLOW TO SAN FRANCISCO BAY FROM TUE SACRAMENTO-SAN JOAQUIN DELTA1

ABSTRACT: Outflow from the Sacramento-San Joaquin river system (Delta outflow) provides about 90 percent of the freshwater flow to San Francisco Bay. Because this river system also supplies most of the water used in California, some believed that annual freshwater flow to the Bay had declined by as much as 50 to 60 percent as water use increased. Consequently, we studied trends in actual Delta outflow and precipitation for the period 1921 to 1986, which is when Delta outflow data are available. We found that there has been no decrease in the annual Delta outflow over this period. In fact, a statistically significant increase in annual Delta outflow of 87 cfa/yr has occurred during the period 1921 to 1986. One reason that Delta outflow has increased is because precipitation has increased faster than water use. Other contributing factors include increased runoff from land use changes, water imports from other areas, and the redistribution of ground water. In addition, statistically significant seasonal trends in Delta outflow were found. Over the period 1921–1986 Delta outflow decreased in April and May and increased from July through November. Changes in other months were not statistically significant. These seasonal changes result primarily from the operation of upstream flood control and water development projects, which store water in the spring and release it in the summer and fall. These seasonal changes are also influenced by a climatic shift that has decreased spring snowmelt runoff and increased late summer through winter precipitation.     

NEW ZEALAND'S NATIONAL WATER QUALITY MONITORING NETWORK - DESIGN AND FIRST YEAR'S OPERATION1

ABSTRACT: The design and implementation of a national surface water quality monitoring network for New Zealand are described. Some of the lessons learned from the first year of operation are also addressed. Underpinning the design, and specified in advance, are the goal and objectives, the data quality assurance system, and the mechanism for data interpretation and reporting. Because of the difficulties associated with the use of a multitude of different agencies, only one agency is involved in field work and one laboratory undertakes the analysis. Staff training has been given a high priority. The network has been designed to give good trend detectability for regular sampling over a 5–10 year period.     

农村商品流通网络模型及其发展趋势

农村商品流通是影响农业发展和农民消费的直接因素，完善农村商品流通网络对开拓农村市场，增加农民收入，发展农村经济具有推动作用。首先论述了农村商品流通网络的内涵；其次提出了基于主导要素的3种农村商品流通网络模型，即交易市场主导型、企业组织主导型和流通技术主导型，并对网络主体及其关系等方面进行了分析；最后提出了农村商品流通网络的发展趋势及其相应对策。     

煤矿企业成长性评价指标与评价方法

本文从煤矿企业生产经营和技术的特点出发,用总资产收益率及增长率与每元经营现金流量及增长率,来定量描述企业成长性的量的表现,从而构造了企业成长性评价指标体系和综合评价方法,定量地测度企业成长性。用企业技术五要素结构分析方法,具体研究了煤矿企业的技术结构,用未确定测度理论定量测度企业技术含量及增长率,来描述煤矿企业成长性的质的表现。根据煤矿企业的特点,研究煤矿企业的成长性及其建立适合煤炭评价指标和方法,为矿业企业可持续发展进行理论指导。     

矿山机械安全技术的现状与对策

从机械故障诊断、机械安全设计、机械安全法规及标准、煤矿安全认证和人员培训等方面,简述机械安全技术的现状及发展趋势;指出目前我国矿山机械安全技术领域存在的主要问题。提出加强高级技术人才培养,强化操作人员培训;建立矿山机械安全设计体系,加强矿山机械高防爆性能的本质安全设计;制定和完善矿山机械安全法规及标准,落实煤矿安全认证和监察;加大技改资金的投入力度等重要对策和措施。逐步提高矿山机械安全技术水平,从而保障煤炭生产设备的安全高效运行。