Redundancy and the choice of hydrologic indices for characterizing streamflow regimes

The utility of hydrologic indices for describing various aspects of streamflow regimes has resulted in their increased application in riverine research. Consequently, researchers are now confronted with the task of having to choose among a large number of competing hydrologic indices to reduce computational effort and variable redundancy prior to statistical analyses, while still adequately representing the major facets of the flow regime. The present study addresses this concern by providing a comprehensive review of 171 currently available hydrologic indices (including the commonly used Indicators of Hydrologic Alteration) using long‐term flow records from 420 sites from across the continental USA. We highlight patterns of redundancy among these hydrologic indices and provide a number of statistically and ecologically based recommendations for the selection of a reduced set of indices that can simultaneously (1) explain a dominant proportion of statistical variation in the complete set of hydrologic indices and (2) minimize multicollinearity while still adequately representing recognized, critical attributes of the flow regime. In addition, we examine the transferability of hydrologic indices across ‘stream types’ by identifying indices that consistently explain dominant patterns of variance across streams in varying climatic and geologic environments. Together, our results provide a framework from which researchers can identify hydrologic indices that adequately characterize flow regimes in a non‐redundant manner. In combination with ecological knowledge, this framework can guide researchers in the parsimonious selection of hydrologic indices for future hydroecological studies. Copyright © 2003 John Wiley & Sons, Ltd.     

拱坝坝顶位移前倾的原因分析

拱坝坝顶位移前倾是一种非常普遍的现象．通过分析拱坝破坏过程中的位移场，指出前倾的原因除了混凝土的膨胀外．还可能是由于坝体的开裂所致。并且提出了监测建议和判断方法。     

东乡铜矿的环保综合治理

介绍东乡铜矿井下水的治理和综合利用、井下废石的处理以及选矿尾砂的综合应用 ,井下高温毒气的治理、尾矿坝的复土植被并继续为生产服务等环保综合治理情况。     

黄龙带水库大坝安全监测自动化总体设计

黄龙带水库大坝的自动化监测项目包括坝基水平位移、垂直位移与转动监测、坝身及坝基的的渗漏量监测、气温与坝温监测、库水位监测及基础渗坟监测等。众多的自动化仪器与数据自动采集与管理软件系统构成了一个较为典型的比较全面的自动化监测系统，是国内大坝安全监测中自动化程度最高的监测系统之一。坝基水平位移自动化监测系统布置在１２１ｍ高程廊道中，通过埋没在１２１ｍ高程基础廊道里的遥测垂线坐仪进行量测，垂直位移自动化     

Coarse woody debris in stream channels in relation to river channel management in woodland areas

Although river channel management now generally uses soft rather than hard engineering techniques the considerable research achieved for woodland river channels has not been completely collated with reference to management implications. Research results from 22 research papers show how debris dams have a significant influence upon the morphological, the process and the ecological aspects of channels; vary in their permanence, and differ in stability according to the overall organic matter budget. A summary diagram contrasts the impact of dams on river channel morphology, process and ecology before and after dam removal. Four major types of specific recommendation about the management of channels in woodland areas are identified from 29 research papers are that (1) management should be undertaken against a background knowledge of the behaviour of coarse, woody debris under natural conditions and that the organic matter budget should be disturbed as little as possible; (2) logging operations should minimize the amount of disturbance to, and disruption of, channel processes; (3) management should optimize the maintenance of habitat diversity and minimize the ecological disturbance to the channel; (4) in some areas specific management practices may require the introduction of new material into the channel. These recommendations are applied to the New Forest, southern U.K., which has a long history of clearance and management of coarse woody debris and where the requirements for clearance in relation to fish, drainage, and aesthetic impact can be achieved by minimizing the amount of removal of material from the river channel. In managing channels with debris dams in woodland areas, it is desirable to work with the river in a holistic basin context.     

Seismic response of an earth dam: finite element coupling analysis and validation from centrifuge tests

Variations in acceleration and excess pore water pressure during a seismic event are critical early-warning indicators of an impending dam collapse.To assess these variations,the seismic responses for three simplified model dams,based on cross-sections through a real earthen dam,were assessed with numerical simulations and centrifuge tests.A normalized root-mean-square error was utilized as a comparison index to assess the closeness between simulated and the recorded values.Assuming that the experimental records are reliable,the reliability of the numerical program was evaluated using this root-mean-square error estimation approach.Explanations for inconsistency between the two approaches are presented.The conclusions are drawn from the results of the three model dams.     

India’s water management debate: is the ‘civil society’ making it everlasting?

Abstract

This article discusses the bias of the growing constituency of civil society activists in India against conventional water management solutions implemented by the government, and the ‘alternatives’ they champion, which force the government to enter into an endless debate with these groups. The article goes into the fundamental reasons for this bias, and identifies four types of civil society activist: ‘professional’, ‘ideologue’, ‘romantic’ and ‘doomsday prophet’. The article also argues that water bureaucracies in India should adopt evidence-based policy making, subjecting the ‘alternatives’ to the same degree of scrutiny as the conventional ones, to end the policy dilemma, while enhancing the overall quality of design, execution and management of projects for better outcomes.     

高混凝土拱坝长期安全运行反馈分析

以李家峡大坝为例,总结分析高混凝土拱坝长期运行中坝基变形偏大、左右1/4拱变形不对称、左右2087高程扬压力异常和地温较高等4方面典型现象,结合高水位原型试验、综合原型观测资料正分析、反演分析和有限元分析,并借助规律分析、关联分析和归纳总结等手段,综合判断李家峡大坝的工作性态。结果表明:李家峡大坝坝体水平位移变化规律总体正常,大坝运行状态良好,设计论证分析正常,大坝基础经处理后,满足安全的要求,具备足够的超载安全度。     

混凝土面板堆石坝接缝止水的实验和分析

混凝土面板堆石坝周边缝止水的损坏是其漏水的主要原因。针对工程实用形式的周边缝铜止水和ＰＶＣ止水，首次进行了承受错位变形的破坏实验，揭示了止水极限变形能力和开裂规律，提出了接缝止水的计算模型、设计准则及提高铜止水极限抗裂能力的工程措施。     

Suckling behavior of calves in seasonally calving pasture-based dairy systems,and possible environmental and management factors affecting suckling behaviors

In recent years, interest has been increasing in whether farmed animals are able to live a reasonably natural life, with one particular area of concern being calf-dam separation. The objectives of this study were to monitor the timing and frequency of suckling behavior of calves left on pasture to suckle their dams for up to 24 h (interquartile range 4.0–15.5 h) and to investigate possible risk factors that may contribute to any variability seen. Over 2 yr, a convenience sample of 8 farms (4 in the North Island, 4 in the South Island of New Zealand) were involved in an observational study where cows and calves were observed for 24 h a day over a 2-wk-long period per farm. During the observation period, farmers continued to remove calves at the same frequency they normally did (which ranged from once a day to 4 times a day). Cows (between 2 and 12 yr old) and calves were observed from a scissor lift in or beside the calving paddock. Cows had numbers written on them, and observers used binoculars and spotlights. Observers recorded the length of stage 2 labor, time of birth, standing, and first suckling, number of suckling events, time of calf removal from the dam, temperature where the cows were grazing, and size of the grazing area they were calving in. Dams were body condition scored before calving, and their age was extracted from farm records. A total of 697 calves were observed during the study. A total of 444 of 697 calves [63.7%; 95% confidence interval (CI) = 60.0–67.3%] suckled in the calving paddock (farm range 40.0% to 90.2%). Of the 444 calves that suckled in the calving paddock, 407 (58.4%; 95% CI 54.6–62.1%) suckled within the first 6 h after birth (farm range 33.0% to 83.6%). Individual risk factors associated with the hazard rate ratio (HR) for time to first suckling event were time to standing (calves who took more than 1.3 h to stand had a longer time from birth to first suckle) and age of the dam [compared with calves that were born from dams >7 years of age, calves born to dams that were 2–3 and 4–7 yr of age had a 1.49 (95% CI 1.07–2.06) and 1.19 (95% CI 0.89–1.60) HR, respectively, for time from birth to first suckle in the calving paddock]. Farm risk factors associated with the HR of suckling were frequency of calf collection [calves that were born on farms that collected calves once a day suckled earlier than calves on farms that removed calves more than once a day (HR 1.52; 95% CI 1.25–1.84)] and temperature [a minimum temperature of <10°C within 6 h of a calf being born was associated with a 0.69 (95% CI 0.53–0.89) hazard of suckling in the calving paddock]. We observed very large farm variability that urgently requires further investigation if pasture-based farms are ever to adopt a system where calves remain with their dams for longer than 24 h.