Flood Forecasting with Short-Duration Heavy Rainfall by Using Hydraulic and Sediment Transport Modeling in River Basin-3

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Project title

Code/計畫編號

MOST107-2119-M002-019

Translated Name/計畫中文名

流域短期暴雨降水預報技術結合水砂監測模擬之應用研究-3

Project Coordinator/計畫主持人

Yu-Jia Chiu

Funding Organization/主管機關

National Science and Technology Council

Co-Investigator(s)/共同執行人

賴進松
張雅琪
林永峻
周仲島
李豐佐
張向寬

Website

https://www.grb.gov.tw/search/planDetail?id=12425341

Year

2018

Start date/計畫起

01-01-2018

Expected Completion/計畫迄

31-12-2018

Bugetid/研究經費

2004千元

ResearchField/研究領域

防災工程

本計畫研究課題為「A-04短期暴雨降水預報技術結合水砂監測模擬之應用」。近年來受到全球暖化及氣候變遷的影響，臺灣地區降雨豐枯差距愈來愈大，集水區產水、產砂、水庫淤積及濁度問題逐漸成為常見災害，本研究團隊自104年起即針對淡水河流域進行科技部應用科技方案之「水砂運移機制分析模擬及監測」(I〜III)進行研究，本計畫是與其相關之延續性計畫。然近年來短延時且強降雨的極端型態有增加趨勢，短延時強降雨之迅洪(Flash flood)事件導致之災害頻傳，譬如2012年蘇拉颱風、2015年蘇迪勒颱風及2016年6月豪雨，均導致新店溪流域山洪暴發與河川洪水漫溢至民宅，2017年6月豪雨亦造成大武崙地區溪水暴漲，以及造成道路及民宅淹水。上述事件中尤以2015年蘇迪勒颱風為甚，上游流域之國有林班範圍內產生許多崩塌地，表土沖刷及崩塌地夾帶大量砂石進入河川水體，除了造成河道淤積影響河防安全外，每逢颱風豪雨亦屢屢造成南勢溪及其下游新店溪原水濁度飆升，影響大臺北地區供水穩定及用水品質，如何因應此種區域性短延時強降雨所造成複合型災害衝擊，已是防減災工作的重點項目。另外，水利署第十河川局、臺北翡翠水庫管理局、臺北水源特定區管理局及林務局等相關單位自2015年以來已開始辦理南勢溪流域上游、北勢溪流域及新店溪下游之河道變遷、土砂調查及水庫操作等相關研究計畫，以了解問題成因並希望進而提出因應對策。依上述之實務研發需求，本計畫擬針對新店溪流域因氣候變遷及極端降雨所導致之天然災害(短延時強降雨所導致之迅洪(Flash flood)及河道水砂運移災害)，尤其是南勢溪覽勝橋以下至新店溪直潭壩之間河段進行探討，應用水理輸砂模式，分析探討集水區河道泥砂運移形態，建立監測站之水位-流量及流量-輸砂量相關性，並依據所建立之流量與輸砂量之水砂率定關係式，模擬原水濁度預報資訊，同時建立河川泥砂濃度及濁度關係，以及河道輸砂趨勢及濁度峰值遞移分析，可直接應用於台北市自來水處直潭淨水廠提供取水時段之推估；此外，相關成果亦能就河道變遷及輸砂影響提供集水區保育治理之參考。 In recent years, global warming and climate change affect the hydrological features significantly in Taiwan. The issues of flood, landslides, reservoir sedimentation and water turbidity could turn into be natural disasters during heavy rainfall. Since 2015, our research group has already started to study on modeling and monitoring of flow discharge and sediment concentration in Tamsui river basin. This study is a continuous project to extend application by combining short-duration heavy rainfall forecasting as inputs for modeling flash flood, landslides, reservoir sedimentation and water turbidity. For instance, Typhoon Saola in 2012, Typhoon Soudelor in 2015 and heavy rainfall in June 2016 had resulted in flash flood events and inundation disasters in the Xindian river sub-basin. In addition, heavy rainfall in June 2017 had induced flash flood to inundate roads and houses along the Dawulun creek. Due to geological condition and topographic conditions in the Nanshi creek, the soil conservation in watershed was significantly affected by flash flood, especially during Typhoon Soudelor in 2015. Abundant amount of sediment yielded from slope surface and landslides was generated in the upper watershed and delivered by flash flood into river and reservoir. The sediment deposition and high-turbid water in river reach will affect the safety of embankment and increase water turbidity of Xindian river to impact water supply. Therefore, the impacts of such multi-hazards are the main issues of disaster prevention. The 10th River management Office of Water Resource Agency, Taipei Feitsui Reservoir Administration, Taipei Water Management Office and Forestry Bureau have launched several studies on topography survey, sediment yield investigation and reservoir operation modification in the Xindian river basin to realize the problem and expect to propose the countermeasures. According to preliminary results, the Nanshi creek watershed is the major source of sediment yield in Xindian river basin. Therefore, this research will focus on disasters of flash flood in Xindian River Basin. The study area is between Lanshen bridge and Zhitan dam. By adopting hydraulic and sediment transport models to investigate flow discharge and sediment transport mechanism within the study river reach. Not only the relationship between flood discharge and water stage will be established, but also the relationship between water discharge and sediment concentration will also be established. These relationships will be applied to predict the tendency of water quality and provide useful operational timing of water supply intake. The simulation results of sediment transport and topographic changing are also can provide valuable information for watershed conservation management.

Keyword(s)

短延時強降雨
水理輸砂模擬
水砂率定關係
原水濁度預報模擬
Short-duration heavy rainfall forecasting
sediment transport modeling
relationship of discharge and sediment concentration
water turbidity prediction

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Flood Forecasting with Short-Duration Heavy Rainfall by Using Hydraulic and Sediment Transport Modeling in River Basin-3

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