水库型滑坡灾害综合灾情评价模型研究

分析了滑坡事件的成灾机理,认为滑坡的灾害效应包含孕育灾害的自然环境、社会环境和自然-滑坡体-社会相互作用系统.在此基础上,将滑坡灾害综合灾情评价结构体系分为危险性评价、易损性评价、破坏损失评价、防灾减灾工程评价四个部分.针对水库型点源滑坡,建立了综合灾情评价的连续函数模型.     

EXPERIENCE WITH THE 303-208-201 STUDY RELATIONSHIPS1

ABSTRACT: The current 201 study by the Bergen County Sewer Authority illustrates possibilities for improving the currently defined relationships between 201, 208 and 303 studies. The Bergen County Sewer Authority serves 115 square miles in northeast New Jersey, providing sewerage service to 507,000 people in 43 municipalities. Its STP discharges to the Hackensack River, a tidal estuary recently classified as Water Quality Limited, and which receives significant non-plant loading. The subject 201 study is concurrent with 208 and 303 planning by NJDEP. Preliminary evaluations show that detailed 201 work can affect the conclusions of 303 and 208 studies, and that a wider (environmental - social as well as economic) interpretation of cost-effectiveness can demand re-examination of prior assumptions and decisions, a task not typically part of 208–303 work. Increased flexibility is needed in applying 303 and 208 recommendations to defining 201 studies and NPDES permit criteria, particularly in analysis of water use objectives, water quality parameters and future flows, loadings and facility costs. Further, perception of alternatives can be clarified by broadening analysis of costs and control and plant strategies. Inclusion of 201 planning at all stages of regional planning can synergistically improve the total planning process.     

MAPS - A PLANNING TOOL FOR CORPS OF ENGINEERS REGIONAL WATER SUPPLY STUDIES1

ABSTRACT: A computer program (MAPS - Methodology for Areawide Planning Studies) has been developed by the U.S. Army Corps of Engineers, Waterways Experiment Station to assist planners in producing a comprehensive array of alternatives without sacrificing the detail and accuracy of the analyses. MAPS is a set of computer based models which can be used to simulate the water resource alternatives and to develop planning level design and cost estimates. Two application examples are discussed. The Salinas-Monterey (California) Urban Study sought to identify and determine cost of combinations of water source, transmission, and treatment to meet an array of water needs in future years. The Nashville (Tennessee) Urban Study had similar objectives but the output was prepared on a service area basis for more than 40 such units. Using MAPS it was possible to prepare planning level design and cost estimates for a very large number of alternatives.     

SELECTING A METHOD FOR ESTIMATING SUBSTANCE LOADINGS1

ABSTRACT: Four simple methods for estimating mass transport are evaluated in terms of the assumptions made about the properties of the data set being analyzed. The basic difference between the four methods considered are their assumptions regarding the manner in which concentration is distributed and the relationship between concentration and discharge. The most precise estimates of mass transport into and out of Schwatka Lake, Yukon Territory, were obtained from the model which assumes that concentration is log normally distributed and independent of discharge.     

STATISTICAL TERMINOLOGY: DEFINITIONS AND INTERPRETATION FOR FLOOD PEAK ESTIMATION1

ABSTRACT: Considerable effort is expended each year in making flood peak estimates at both gaged and ungaged sites. Many methods, both simplistic and complex, have been proposed for making such estimates. The hydrologist that must make an estimate at a particular site is interested in the accuracy of the estimate. Most methods are developed using either statistical analyses or analytical optimization schemes. While publications describing these methods often include some statistical measure of goodness-of-flt, the terminology often does not provide the potential user with an answer to the question,‘How accurate is the estimate?’ That is, statistical terminology often are not used properly, which may lead to a false sense of security. The use of the correct terminology will help potential users evaluate the usefulness of a proposed method and provide a means of comparing different methods. This study provides definitions for terms often used in literature on flood peak estimation and provides an interpretation for these terms. Specific problems discussed include the use of arbitrary levels of significance in statistical tests of hypotheses, the identification of both random and systematic variation in estimates from hydrologic methods, and the difference between accuracy of model calibration and accuracy of prediction.     

SPACE-TIME VALIDATION OF A THUNDERSTORM RAINFALL MODEL1

A probability model for predicting the occurrence and magnitude of thunderstorm rainfall developed in the southwestern United States was tested in the metropolitan Chicago area with reasonable success, especially for the moderate to the extreme runoff-producing events. The model requires the estimation of two parameters, the mean number of events per year and the conditional probability of rain given that an event has occurred. To tie in the data from more than one gage in an area, an event can be defined in several ways, such as the areal mean rainfall exceeding 0.50 inch and at least one gage receiving more than 1.0 inch. This type of definition allows both of the model parameters to be obtained from daily warm-season rainfall records. Regardless of the definition used a Poisson distribution adequately described the number of events per season. A negative binomial distribution was derived as representing the frequency density function for rainfall where several gages are employed in defining a storm. Chicago data fit both distributions very well at events with relatively high return periods. The results indicate the possibility of using the model on a regional basis where limited amount of data may be used to estimate parameters for extensive areas.     

ON THE MISMATCH BETWEEN DATA AND MODELS OF HYDROLOGIC AND WATER RESOURCE SYSTEMS1

ABSTRACT: Many difficulties exist in the matching of models with data. This paper identifies elements of this problem and discusses considerations involved in model evaluation. The well known multivariate linear regression model is used to illustrate the distinctions between accuracy and precision and between estimation and prediction (because the model is commonly misused.) No amount of additional data will improve the accuracy of a poor model. A high R², while indicative of a good matching between the observed data and model estimates, is a poor criterion for judging adequacy of the model to make good predictions of future events. Model evaluation also includes the problem of introducing secondary data and proxy variables into a model. Secondary data frequently enter, for example, the mass, energy and water budget equations because of difficulties in measuring the primary variables. Proxy variables arise because of a desire to collapse a vector of incomparable values, say, of water quality into a single number. Review of the above issues indicates that model evaluation is a multi-criterion problem, often imbedded in a larger framework where models are intended to meet multiple objectives. The mismatch of models and data has increasing legal and social consequences.     

基于χ~2优化方法的铸钢侧架原始裂纹尺寸分布研究

将铸钢侧架清砂后未经修复的原始裂纹尺寸进行了统计 ,综合运用参数的点估计方法和区间估计方法 ,以置信区间作为优化的约束条件 ,提出了对检验值进行最优化处理的方法 ,并运用二参数约束非线性优化方法的直接解法 ,搜索出最佳点估计值。经过对裂纹尺寸分布参数的计算证明 ,其结果符合对数正态分布     

高级组合塘处理污水系统简介

氧化塘处理污水的全过程与天然水体自净相似,因此具有处理成本低、运行稳定等优点,但由于它所存在的缺点,如负荷低、占地大、恶化周围环境等,限制了它的使用,为解决这些缺点,产生了一些新型塘及塘系统,本文介绍了其中的一种,即高级组合塘系统。     

天津市滨海地区综合防灾减灾的策略研究

分析了天津市滨海地区历史自然灾害的历史和特点，预测了该地区未来一段时间和最近1－2年可能发生的主要自然灾害，提出了本区综合防灾减灾的策略和目标，为该区综合防灾减灾规划的制订提供了依据。