Research press release


Nature Geoscience

Modifying mountain river systems


S Bonnetは、室内実験を用いて山脈地帯の地形をモデル化し、山脈が雨を降らす雲の動きを妨げて山脈の背後に乾燥した「陰」をもたらすという、山脈地帯の隆起運動の効果と非対称な降雨の効果とを結びつけた。彼は分水嶺がこれらの条件に応答して山地の乾燥した方面へ移動することを発見した。それにつれて、山脈の乾燥した側にある流路は分かれ始め、より多くの川と小さいがより多くの放出路をもつ盆地を形成する。


A newly identified mechanism that controls the spacing of river basins in growing mountain systems is reported in a study published online this week in Nature Geoscience. A constant relationship between the position of mountain divides and the number of river-system outlets has been observed in nature, but the processes controlling this connection had been previously unknown.

Stephane Bonnet used laboratory experiments to model the topography of a mountain range while combining the effects of the upward motion of the mountain range and asymmetric precipitation ― in which a mountain range blocks the movement of rain-producing clouds, casting a "shadow" of dryness behind the range. He found that the mountain divide responded to these conditions by migrating towards the dry side of the range. And as it did, channels on the dry side of the range began to split, forming more rivers and smaller but more plentiful drainage basins.

Bonnet suggests that evidence of this process can be found in the Aconquija Range of Argentina.

doi: 10.1038/ngeo666


メールマガジンリストの「Nature 関連誌今週のハイライト」にチェックをいれていただきますと、毎週各ジャーナルからの最新の「注目のハイライト」をまとめて皆様にお届けいたします。