沖決
外观
![](http://upload.wikimedia.org/wikipedia/commons/thumb/4/47/Mississippi_Delta_1976.jpg/300px-Mississippi_Delta_1976.jpg)
沖決(英語:avulsion)是指一條河流廢棄原河道而流向新河道。當河道梯度比地面坡度小,就會發生沖決。[1]在河流三角洲,沖決很常見。[2]此過程也稱為三角洲換位。例如密西西比河的鳥足形三角洲,它就是由連續的沖決形成。
當一條河流進入海洋時,會形成一個單獨的三角洲[3],隨著三角洲向海推進,河道變長坡度也變低,河道變得不穩定。在重力作用下,河流將趨向最直接的下坡方向流動。在洪水期,河流能溢出其天然堤壩,沖決出一條新的陡坡河道。[4]
相關條目
[编辑]參考文獻
[编辑]- ^ Slingerland, Rudy; Smith, Norman D. (2004). "River Avulsions and Their Deposits". Annual Review of Earth and Planetary Sciences. 32: 257–285. Bibcode:2004AREPS..32..257S. doi:10.1146/annurev.earth.32.101802.120201
- ^ Marshak, Stephen (2001), Earth: Portrait of a Planet, New York: W.W. Norton & Company, ISBN 0-393-97423-5 pp. 528–9
- ^ Stanley, Steven M. (1999) Earth System History. New York: W.H. Freeman and Company, ISBN 0-7167-2882-6 p. 136
- ^ Perignon, M. C. (2007). Mechanisms governing avulsions in transient landscapes: Analysis of the May 2006 Suncook River Avulsion in Epsom, New Hampshire (S.B. Thesis). Massachusetts Institute of Technology