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Please use this identifier to cite or link to this item: http://ntour.ntou.edu.tw:8080/ir/handle/987654321/29806

Title: 陡坡與緩坡河道洪水預警系統之建立
Development of real-time flood warning system for steep and mild channels
Authors: Ya-Chi Huang
Contributors: NTOU:Department of Harbor and River Engineering
Keywords: 運動波模式;動力波模式;洪水預警系統
kinematic-wave model;dynamic-wave model;flood warning system
Date: 2011
Issue Date: 2011-11-23T03:18:23Z
Abstract: 台灣地文環境特殊,山勢高聳地形陡峻,山區集流時間甚短,加上近年來受到全球氣候變遷的衝擊,極端降雨發生頻率增加,常於颱風及夏季暴雨期間帶來大量豪雨,造成山區逕流快速匯入河川,以致河川水位暴漲,若排水系統無法即時疏排逕流,則短時間內將造成下游居民生命安全與財產之威脅,故建立洪水預警系統實有其必要性,可於洪水來臨期間進行即時河道水位預測,提供決策者疏散居民及救災人員提前救災準備之相關資訊,以減輕災害的可能性。 本研究所建立之河道洪水預警系統,是以國內常用於河系演算之NETSTARS模式為主要架構。然而因台灣山區坡陡之特性,於動力波河道演算模式時常會發生數值不易收斂,故本研究於河道演算模式中加入常用於計算陡坡渠道之運動波模式,以期解決該數值演算之不穩定問題。為考慮運動波模式僅適用於陡坡渠道,及動力波模式於陡坡演算上之問題,故研究首先利用因次分析推求影響運動波與動力波交界斷面之獨立變數,而後以研究中所建立之結合運動波與動力波之河道演算模式,進行一連串運動波與動力波交界斷面因子之數值試驗,試驗結果顯示,於矩形試驗渠道中,運動波與動力波交界斷面位置,可以渠流運動水流數與福祿數之關係來描述;而自然河川渠道中,則可單純以福祿數為運動波與動力波模式作分界,如此確立動力波及運動波之適用範圍,提供後續河道洪水演算之參考應用。 研究中蒐集大里溪流域水文、地文及歷年颱洪紀錄資料,應用地形性降雨逕流模式,推估降雨於次集水區及殘流域區塊所產生之逕流,並將各區塊逐時之逕流於鄰近河道斷面注入河道,以進行河道水位預測工作,最後將結果於預警系統網路平台展示。研究結果顯示,洪水預警系統於大里溪流域模擬結果良好;故颱洪期間可利用本系統進行即時河道水理演算,以達到河道洪水預警之目的。
Taiwan has steep hillslope and usually receives concentrated rainfall during typhoons and summer rainstorms, which usually result in a large amount runoff peak. More recently, impacts from global climate change induce more serious flood disaster to cause tremendous losses. In severe rainstorms, if drainage system can not drain stormwater in time from overland areas to channels, serious hazard will occur in downstream flat areas. Hence, a warning system providing flooding information in advance for evacuation to mitigate the possible disaster is considered important. In this study, flood routing in channel is basically based on the NETSTARS (Network of Stream Tube model for Alluvial River Simulation) model. Since dynamic-wave model usually resulting in numerical instability in steep channel reaches, a kinematic-wave approximation was adopted for flood routing to provide a numerically stable model. In considering the kinematic-wave method can only be applied to steep channel reaches with acceptable precision, a dimensional analysis was performed to determine the independent variables which significantly affect the choosing of the demarcation point to separate dynamic- and kinematic-wave routing methods. Series numerical experiments have been performed in this study. Numerical results show that the hydraulic characteristics at the demarcation in channel with rectangular channel cross sections can be described by using kinematic-flow number and Froude number, and they can only be correlated to Froude number in channel with natural irregular cross sections. Geomorphologic and hydrological records from Dali River basin were collected in this study. A geomorphology-based runoff model was used to estimate storm runoff from tributaries and channel lateral-flow areas and then adjoin into the channel-flow routing system for water stage forecasting on a web platform. Simulated results generated from the proposed flood routing system were found consistent with the flow records. It is therefore promising to apply the developed methodology for a real-time flood warning system in practice.
URI: http://ethesys.lib.ntou.edu.tw/cdrfb3/record/#G0M98520004
Appears in Collections:[河海工程學系] 博碩士論文

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