Detection of nonstationarity in hydrologic time series

[[abstract]]Detection of changes in hydrologic time series due to intervention by man or natural causes is an important problem. Although intervention analysis has been used in the recent past to analyze nonstationary hydrologic time series, the necessity to specify a model of change and an initial time at which the time series has started to change are obvious disadvantages of intervention analysis. An alternative to intervention analysis is a method which is based on spectral characteristics and an exponential moving average model. The basic objective of the research discussed in the present paper is to test this alternative method. The model is tested by using synthetic uncorrelated and correlated data with step and gradual changes as well as by using real hydrologic time series. The sensitivity of the model to different parameters is also explored. The alternative model is found to be quite accurate in detecting changes in hydrologic time series

[[alternative]]The Research on Industrial Water Management

[[sponsorship]]中興大學土木系[[conferencedate]]20081212~20081212[[booktype]]紙本[[iscallforpapers]]Y[[conferencelocation]]臺中, 臺

[[alternative]]The Mechanism of Risk Management for Water Resources Policy

[[sponsorship]]中興大學土木系[[conferencedate]]20081212~20081212[[booktype]]紙本[[iscallforpapers]]Y[[conferencelocation]]臺中, 臺

[[alternative]]A Study on the Metropolis Inundation Scenario Simulation Caused by Extreme Storm：Main and Sub-Project: Extreme Storm Scenario Analysis and Its Rainfall-Runoff Simulation (I)

[[abstract]]台灣具有特殊之地理位置、地形與天然氣候等條件，再加上近年來全球暖化及氣候變遷等因素，愈形加劇氣候異常之發生機率與增大極端暴雨事件規模。這些極端異常暴雨一旦發生在大台北都會區，使得河川洪水位與市區排水超出既有之防洪、排水設計標準，造成堤防溢堤、破堤或抽排系統功能喪失等複合型災害發生，將嚴重威脅大台北都會區約500 萬人口之生命財產安全，並極易引發如美國卡崔娜(Katrina)颶風侵襲後之嚴重社會失序問題。因此，強化都市地區極端暴雨之相關災害防治與應變能力等非工程之預警方法，仍為現階段洪災科技發展之重點課題。本計畫擬以台北都會區為研究對象，模擬都會區上游山區發生各種延時之可能最大降雨，引致淡水河、基隆河、景美溪等河川瓶頸地段堤防發生多處溢破堤狀況，而平地都會區內又遭逢短延時之極端降雨強度暴雨侵襲，引致抽排水系統喪失功能等共伴之複合型淹水境況。本整合型計畫預計以三年期間完成台灣地區極端暴雨模擬模式，應用降雨—逕流模式模擬大台北都會區多種極端暴雨虛擬情境之流量，並結合堤防溢堤或破堤洪流演算模式、地表淹水模擬模式及排水系統分匯流之數值模式，完成台北都會區在遭遇極端暴雨侵襲而發生超過設計標準之情況下所可能發生之複合型災害模擬，最終完成極端暴雨情境分析之淹水境況模擬展示系統，提供相關單位防救災緊急應變演練上之參考與應用。[[abstract]]Owing to its special geographical, territorial, and climatical endowments, plus recent global warming and climate change effects, Taiwan is prone to suffer frequent climate abnormality and larger-than-normal extreme storm events. Should these extreme events happen in Taipei Municipal Area, drainage facilities designed to cover normal events might be dysfunctional, which in turn cause serious social and economic problems as Hurricane Katrina did in New Orleans. Enhancing non-engineering warning methods and emergency response capabilities for extreme storm events have been a key issue in disaster preventing technology development. Mainly targeted in Taipei Municipal Area, this project simulates various compound inundations situations. Compound inundation are caused by both levy overflow in the upstream areas, such as in Tamsui River, Keelong River, and JinMai River bottleneck sectors, and draining failures in the downstream areas when it suffers short-duration, high intensity storm attacks. This integrated research project intends to accomplish extreme storm event simulation models, extreme storm events mathematical models by employing rainfall-runoff, storm discharge computation, and overland flow and drainage computation model, compound disaster simulation when Taipei Municipal Areas is suffering extreme events, and finally the display system for extreme storm events for disaster preventing and emergency response purposes.[[sponsorship]]國科會永續發展研究推動委員會[[conferencetype]]國內[[conferencedate]]20090203~20080104[[booktype]]紙本[[iscallforpapers]]Y[[conferencelocation]]臺北市, 臺

[[alternative]]Deriving LL-moments for Low Tail Statistical Analysis and Its Application to Drought Events

[[abstract]]線性動差法在諸多機率分布函數之參數推估方法中，受離群值(outlier)之影響較小、近似無偏估及推估高效率等方面之優點已廣為所知；惟在極端事件上不論是洪水之高值端(higher-tail)或枯水之低值端(lower-tail)的部分，由於該方法之觀測資料線性組合與給定極端值部分過小之權重，致容易發生傳統L-moments方法在極端值推估上之妥適性問題。本研究以高尾端1997年Wang發展之LH-moments為基礎，進一步針對低值端之部分衍導「修正型低尾端線性動差法(LL-moments)」之各階動差計算式，以提供枯旱極端事件方面之應用。本研究以三參數之通用極端值分布(the generalized extreme value, GEV)為例，依序推導其1至4階之LL-moments。研究中，一方面利用數值方法探討不同形狀參數(shape)下，LL-moments方法於枯旱事件之適用性；另一方面，選取高屏溪流域之六龜、荖濃兩處流量站歷年最低旬流量資料進行實務分析及應用。希冀藉由低尾端線性動差相關方法之探究及實務上之驗證，提供台灣地區乾旱頻率分析及水資源經營管理之參考。[[abstract]]L-moments have the advantage of providing parameters estimates that are nearly unbiased, highly efficient and not much influenced by outliers in the data. Because of L-moments are linear combinations of the observed data values. Besides, extreme sample values are given little weight in the estimation, the sample information about the higher-tails or lower-tail of the distribution may not be adequately evaluated. In this paper, LL-moments are derived, which is modified L-moments. It is adopted to characterize the lower part of extreme events, such as drought. Meanwhile, it also referred and based on LH-moments algorithm. The generalized extreme value (GEV) distribution, all with three parameters, are illustrated to derive the forms of estimation of LL-moments. The first order to forth order forms of moments are expressed in this study. First of all, the numerical algorithm is adopted, giving different shape parameters, to explore how suitable is LL-moment applied to evaluate the severity of drought events. Furthermore, the 10-day annual minimum flows of two stations in Kao-Pin River, Liu-kwei and Lao-nong, are selected to apply for estimating low flow quantiles. It should be useful for getting evaluation drought severity to adjust water resources management tactic at the right time and lower the risk of regional water supply.[[sponsorship]]台灣?公農田水利會[[conferencetype]]國內[[conferencedate]]20081028~20081028[[booktype]]紙本[[iscallforpapers]]Y[[conferencelocation]]臺北市, 臺

[[alternative]]The Research of Separating Industrial Water from Public Supply System

[[abstract]]過去在工業用水比重尚低的年代，工業用水以自行取用地下水為主，隨著工業發展及地下水開採受到嚴格管制，越來越多工廠傾向由自來水系統供水。由於自來水系統主要供應生活飲用水使用，其所供應水質高於許多工廠可正常生產及運作下之水質，越多工廠共用自來水系統，水資源整體利用效率可謂越低。本文主要探討台灣工業用水現況與問題，並參酌國外經驗及國內環境，綜合評估水源、水質及最適規模等，提出推動工業與生活用水管線分離之策略建議。[[abstract]]In the past, groundwater was a major resource of industries in Taiwan. With the development of industries and highly restricted of extracting groundwater, more and more industrial water are supplied from public supply systems. Public supply system supplies water with higher quality than some product development process demands for satisfying drinking and domestic use. Low water use efficiency with the more industrial water supplied from public supply system. This paper reviews industrial water use problems, assess raw water sources, water quality demands and economic scale refer to abroad experience and domestic industrial development present situation and proposes the planning strategies.[[sponsorship]]台灣?公農田水利會[[conferencetype]]國內[[conferencedate]]20081028~20081028[[booktype]]紙本[[iscallforpapers]]Y[[conferencelocation]]臺北市, 臺

[[alternative]]Study on the Estimation of Regional Flow Duration Curve for the Insufficient Data Area：An Illustration of Southern Taiwan

[[abstract]]本研究利用年百分數流量和年平均逕流量之比與流域面積建立年百分數流量之區域特徵迴歸方程式,研究中藉區域特徵迴歸誤差之校正,推求未設站或資料缺乏流量站地點之區域流量延時曲線,並以南部地區所選九個流域三十九個流量站資料,經驗證其精確度甚高,其累積總誤差大都於20%以內可運用於推求區域內。[[abstract]]In this study, the regional characteristic regression function was built by using the ratio of the percentage of yearly flow equal to or greater than indicated flow and annual average discharge versus the watershed area. The flow duration curve of the ungauged and the insufficient data area was simulated by means of the adjustment of the errors of regional characteristic regression function. According to the results of the data from thirty-nine stations of the basins selected in south Taiwan, most of the errors of area under simulated flow duration curve are within 20%.[[sponsorship]]台灣大學農業工程系; 台灣大學水工試驗所; 中國土木水利工程學會[[conferencetype]]國內[[conferencedate]]19960708~19960709[[booktype]]紙本[[iscallforpapers]]Y[[conferencelocation]]臺北市, 臺

[[alternative]]Frequency Analysis of Correlated Data：Synthetic Data Study

農委會水利特刊; 第5號[[abstract]]本研究以合成資料探討當資料不滿足極端 值理論之兩項基本假設:(1)族群內資料須屬同 一機率分布且相互獨立,及(2)族群內資料樣本 數需趨近無限大,時對極端值I型分布之適用性 。研究中採用機率點繪相關係數檢定 ( Probability plot correlation coefficient test)法,藉其能 正確反映I型誤差(Type I error)之特性,由通過檢 定之組數是否合理,探討相關性資料於極端值I 型分布之適用性及其應用時之效力。 研究結果顯示,資料之相關性愈強,極端值I 型分布愈不適用;即使當族群內樣本數為365時, 亦不保證極端值I型分布適用,主要因受族群內 資料偏態係數影響。同時,當族群內資料之偏 態係數接近極端值I型分布理論偏態係數值1.139 時,不論相關性及族群內之樣本數大小,極端值I 型分布皆適用。另,機率點繪相關係數檢定法 應用於極端值I型分布時其效力遠較K.S.檢定為 佳。[[abstract]]The aptness of extreme value type I distribution for the data which do not satisfy the basic assumptions of extreme value theory is investigated by synthetic data in the present study. The basic assumptions are that (1) data within group obey the same probability density function and do not mutually depend each other, and (2) the sample size of each group should approaches infinite. The probability plot correlation coefficient test is employed in this study. This is done by judging whether the percentage of rejecting the null hypothesis is reasonable, since this test preserves the type I error. The results indicates that extreme value type I distribution is not appropriate when the data are highly correlated, and even when the sample size of each group is 365. The major influence factor is the skewness coefficient of data for each group. Meanwhile, no mater how strong the correlation is and how large the sample size of data within group is, extreme value type I distribution is always appropriate whenever the skewness coefficient of data within group is close to 1.139 which is the theoretical skewness coefficient of extreme type I distribution. Besides, the results indicates that the probability plot coefficient test is more powerful than K.S. test.[[sponsorship]]中國農業工程學會; 行政院農業委員會; 台灣大學農業工程研究所[[conferencetype]]國內[[conferencedate]]19941208~19941208[[booktype]]紙本[[iscallforpapers]]Y[[conferencelocation]]高雄, 臺

[[alternative]]Studies on Wakeby Distribution and Its Application on the Annual 1-day, 2-day and 3-day Maximum Rainfall in Taiwan Area

[[abstract]]水文頻率分析涉及決定資料所屬機率分布 之判定,由於水文資料缺乏易發生誤判,而導致 設計水文量不足或過高。 Houghton(1978)提出一具 五參數之威克拜分布(Wakeby Distribution),由於其 涵蓋度,應用於水文頻率分析可免除判定機率 分布之困擾,因此本研究將其與水文頻率分析 中常用之分布(TN、LN2、LN3、EV1、PT3及LPT3)作一 詳盡之比較。研究中使用合成資料分別以模擬 各迴歸週期之理論值及模擬隨機樣本值加以探討威克拜分布之特性,並應用於台灣年一日、 二日及三日最大暴雨量,探討威克拜分布之適 用性。合成資料之研究結果顯示威克拜分布無 論於推估各頻率理論值或擬合樣本值上,其精 確度均較六種常用分布為高。同時,實測資料 研究結果亦顯示威克拜分布較六種常用分布更 適合模擬台灣最大年一日、二日及三日暴雨資 料。[[abstract]]To determine the distribution obeyed by data plays an important role in hydrologic frequency analysis. Due to the small sample size of hydrologic data, the result is usually less accurate. This results in improper design. Wakeby distribution which has five parameters has been proposed by Houghton in 1978. Since Wakeby distribution is flexible, the intractable problem of determination the distribution obeyed by data could be avoided. It was investigated in depth in the present study. The results obtained by Wakeby distribution were compared with those of obtained by the distributions ( TN, LN2, LN3, EV1, PT3, and LPT3) frequently used in the hydrologic frequency analysis. In the present study, the synthetic data were used to investigate the properties of Wakeby distribution by the accuracy of fitted data and the theoretical values of some specified return periods. Meanwhile, the annual 1-day, 2-day and 3-day maximum rainfalls in Taiwan area were employed to study the aptness of Wakeby distribution. The results of synthetic data indicated that the accuracy of estimating the theoretical value of return periods or the accuracy of fitting the sample data was higher than those of six frequently used distributions. Furthermore, the results of observed data also indicated that Wakeby distribution was the most appropriate for analysis of maximum annual 1-day, 2-day and 3-day rainfall data in Taiwan.[[sponsorship]]中國農業工程學會; 行政院農業委員會; 台灣大學農業工程研究所[[conferencetype]]國內[[conferencedate]]19931217~19931217[[booktype]]紙本[[iscallforpapers]]Y[[conferencelocation]]臺中市, 臺

[[alternative]]Review and Improvement of the No-Irrigation Policy for Transferring Agricultural Water

[[abstract]]近年來由於都市人口急速增加、工商業用水激增、水文氣象不佳及水資源開發不易等因素影響，於91至96年之6年期間，除94、96年外，台灣部分地區為穩定民生及產業用水，均依水利法第19條辦理停灌措施，期間經各單位通力合作，均順利達成穩定供水目標。辦理停灌措施所需配合之工作繁複，依過往執行經驗，目前有三項課題亟待釐清解決：經費籌應不易、沒有全面獲致共識之補償標準及停灌公告時間常逾農作時期。本文主要針對前述三項課題探討解決對策，經考量國內法規及利害關係人相關意見，提出三項建議，包含1.設置「公共給水緊急應變基金」；2.統一停灌措施補償標準「以最近一年已公佈統計年報，同期蓬萊種稻米之農家賺款另加5%補償」及3.訂定育苗、秧田、整田與本田之最後期限。[[abstract]]Government stopped water supply in some irrigation districts according to the article 19 of Water Law due to irregular weather patterns characterized by sever drought continued during dry seasons of 2002, 2003, 2004 and 2006. Cooperation by the related communities ensured the stable supply of public water and industrial water. According to the experiences, there are still 3 issues need to be solved: 1. financial resources, 2. standards of compensation, and 3. announcement timing. This paper research the solutions of above issues refer to Water Law and opinions of stakeholders, including: 1. to establish the Emergency Reserve Fund of Public Water Supply, 2. standards for compensation is suggested to refer to the farm family income of japonica rice in Agricultural statistics yearbook in the latest year and plus 5 percentage points, 3. to set the deadline of seed, sow and farm.[[sponsorship]]台灣瑠公農田水利會[[conferencetype]]國內[[conferencedate]]20081023~20081023[[booktype]]紙本[[iscallforpapers]]Y[[conferencelocation]]臺北市, 臺