美国印第安纳大学Gearon, James H.课题组的一项最新研究显示，河流断裂的规则在下游发生变化。相关论文发表在2024年9月18日出版的《自然》杂志上。

课题组研究人员通过量化河流周围的地形来验证这些经典观点，研究显示，这些机制在历史上是分开调用且共同工作的。在海岸附近，当远离河道的斜坡更陡峭时，河流会发生断裂，而不是因为它们处于高位。靠近山麓的情况正好相反；在扇面上，可供选择的路径与下游路径一样陡峭，因此当河流位于周围景观上方时，它们就会断裂。

研究人员对这些发现进行了调和，并提出了一个新的理论框架，该框架确定了哪些河流容易受到断裂的影响，预测了断裂河流的路径。这些一阶断裂规律表明，在许多沿海环境中，断裂风险被低估了，断裂寻路的概率预测可以用最少的信息有效地绘制出危险地图。结果强调，将这些原则应用于风险评估可能特别有利于受断裂影响的全球南方国家。

据介绍，断裂的河流在洪泛区创造了新的通道，相关的洪水会对社会产生深远的影响。人们认为，当水柱在河漫滩上方停留时，或者当河道两侧的坡度比现有河道的坡度更陡时，就会发生河流断裂。

附：英文原文

Title: Rules of river avulsion change downstream

Author: Gearon, James H., Martin, Harrison K., DeLisle, Clarke, Barefoot, Eric A., Mohrig, David, Paola, Chris, Edmonds, Douglas A.

Issue&Volume: 2024-09-18

Abstract: Avulsing rivers create new pathways on the floodplain and the associated flooding can profoundly affect society. River avulsions are thought to occur when the water column becomes perched above the floodplain or when the slope down the flanks of the channel provides a steeper descent than the existing river channel. We test these classical ideas by quantifying the topography around avulsing rivers and show that these mechanisms, historically invoked separately, work together. Near coasts, rivers avulse when the slope away from the channel is steeper, not because they are perched. The opposite is true near mountain fronts; on fans, the alternative paths are similarly steep to the downstream path, so rivers avulse when they are perched above the surrounding landscape. We reconcile these findings and present a new theoretical framework that identifies which rivers are vulnerable to avulsion and predicts the path of an avulsing river. These first-order rules of avulsion suggest that avulsion risks are underestimated in many coastal environments and that probabilistic predictions of avulsion pathfinding can efficiently map hazards with minimal information. Applying these principles for risk assessment could particularly benefit the Global South, which is disproportionately affected by avulsions.

DOI: 10.1038/s41586-024-07964-2

Source: https://www.nature.com/articles/s41586-024-07964-2