溪流匯口形成不同堵河程度之地形特徵

Topographic Characteristics by Level of River Blockage Formed by Confluences

10.29417/JCSWC.202003_51(1).0002

張詩晨(Shih-Chen Chang)；劉宜君(Yi-Jun Liu)；曾名賢(Ming-Hsien Tseng)；黃效禹(Hsiao-Yu Huang)；陳樹群(Su-Chin Chen)

主支流交匯 ； 堰塞湖 ； 堵河程度 ； Tributary confluence ； natural dam ； level of river blockage

中華水土保持學報

51卷1期（2020 / 03 / 01）

13 - 20

繁體中文

本研究蒐集2008至2015年間主支流交匯處有明顯土砂堆積之113次事件，利用地理資訊系統萃取其地形因子（河寬、坡度、交匯角度、匯點高程及集水區面積），探討在不同堵河程度發生的地形條件。結果呈現主支流河寬比與堵河程度有明顯的正相關性，且在主支流河寬相近與交匯角接近90度時，最有可能發生完全堵河之現象。藉由堵河之潛勢地形，未來在劃定土石流潛勢溪流時，可同時評估發生堰塞湖之潛勢區域，以達到防災之目的。

Satellite images were used to collect data on the confluences in Taiwan with considerable deposition for identifying river topography characteristics for different levels of river blockage. To define the levels of river blockage, 113 events from 2008 to 2015 were analyzed using a geographic information system to extract topographic factors, such as river width, slope, confluence angle, elevation, and watershed area. The results revealed that river width ratio and level of river blockage shared a significant, positive correlation, and river blockage occurs where the confluence angle approaches 90°. On the basis of these blockage characteristics, we forecast the potential debris flow torrent and potential areas for natural dams; these forecasts can be used to prevent debris flows into confluences during disasters.

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