Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/34314
標題: 神木集水區土砂產出對陳有蘭溪河道變遷影響之探討
The Chenyulan river morphology change induced by Shenmu watershed sediment yield
作者: 陳少謙
Chen, Shao-Chien
關鍵字: debris flow
崩塌
Sheng-Mu village
landslide
土石流
陳有蘭溪
神木村
出版社: 水土保持學系所
摘要: 台灣山區地質脆弱,加以暴雨集中、雨量大、延時長等原因,造成山區坡地山崩及土石流災害頻傳;由1996年賀伯颱風侵襲造成出水溪上游崩落大量土石後,十多年來神木村屢在颱風豪雨事件而引發出水溪、霍薩溪及愛玉子溪等三溪流集水區嚴重崩塌及土石流災害;而台灣中部山區河川具有坡短流急、洪枯變化差異大等特性;河川演化型態受到土砂產量變化影響,在幾次大型土砂事件造成巨量土砂進入河道可能引發河川型態發展之改變以及沖淤情況加重之慮。本研究將南投縣信義鄉神木村出水溪、霍薩溪、愛玉子溪三溪流集水區自1996年至2009年多期正射影像進行崩塌地數化後判釋其規模以及分佈位置,並對三條溪流匯流後之土砂量進行估算;接著再對下游之陳有蘭溪歷年河川演化過程進行研究,針對河川平面形態及其沖淤特性作說明,探討陳有蘭溪河相演變之成因。 本研究利用正射影像、河川大斷面資料進行神木村三溪流集水區以及陳有蘭溪歷年崩塌以及土砂量進入河道對陳有蘭溪所造成之影響,發現在上游出水溪、霍薩溪以及愛玉子溪之崩塌分布皆以沿岸崩塌為多,地震事件如921集集地震雖將本試區沿岸坡面之強度改變使得土體結構鬆散,但仍以颱風或豪雨事件造成之洪水淘刷為主因。在陳有蘭溪河道變遷部份,河寬具有隨著歷次土砂事件帶來巨量土砂而呈現逐年展寬之情況,而河川平面型態多以辮狀為主;針對河道辮狀指數與土砂量以及河寬關係之研究上,發現河道辮狀指數隨著河川地形區位改變,土砂量則影響河道辮狀指數之大小;亦即土砂量大時河到土砂量足以使得辮狀流路數量增加;而河床沖淤型態則造成地形上之演變,在展寬之河道上辮狀指數亦有增加之趨勢。
Landslide and debris flow events were induced by fragile geology and the high-intensity long-duration rainfall during typhoon seasons since Typhoon Herb in 1996 in the region of Chu-shui creek, Huo-sa creek and Ai-yu-zih creek in Sheng-mu village, Taiwan. Channel conditions such as sediment yield and width of river section are important issues in analyzing river morphology. Behaviors and characteristics in chenyoulan river were infected by amount of sediment input due to typhoon events in recent decade. Therefore, this study analyze the yield of landslide event and discuss the changes between scour and deposition in chenyoulan river, Chu-shui creek, Huo-sa creek and Ai-yu-zih creek. By analyzing the relationship between landslide location and landslide magnitude and estimate the sediment yield induced by landslides in basin area, this study proposed a method to comply the surmise. Result showed that landslides location in this area were generally near the stream instead of the ridge. In order to get the trend of river morphology influenced by sediment input, the study recommended braided index to analyze the plane forms of river channel. It showed that after landslides and debris flow events, the sediment cause by landslides were deposited in river channel. During the process, the width of channel could increase, so did the braided index. Like the result of this, the self-adjustment of river channel will lead the river form as braided river because of amount of sediment input.
URI: http://hdl.handle.net/11455/34314
Appears in Collections:水土保持學系

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