日本广岛大学T. Inoue及其研究团队提出瀑布高度决定上游消退的机制和速度的观点。2023年5月26日出版的《地质学》杂志发表了这项成果。

由于缺乏瀑布高度是如何影响上游瀑布消退机制和速度的数据，研究人员通过测试落差对瀑布消退的影响的实验，来弥补这个知识缺口。实验表明，当基岩强度、沉积物供应和水流量不变时，较矮的瀑布比较高的瀑布消退速度块五倍。这种消退速度差异是由侵蚀机制的变化引起的。较矮瀑布通过形成几个小的、快速侵蚀的基岩台阶(即，循环台阶)而消退，而高瀑布往往形成大型基岩水垫塘，其中侧向水垫塘侵蚀允许端墙下切和随后的瀑布消退。因为瀑布的高度可以部分地由瀑布的形成机制决定，研究结果强调了瀑布消退的速度和随后的景观演化可以由形成瀑布的过程来调节。

据介绍，瀑布是河流网络中受侵蚀最快的部分，但是预测瀑布的自然消退速度非常困难，因为有多种过程可以驱动瀑布遭受侵蚀。

附：英文原文

Title: Waterfall height sets the mechanism and rate of upstream retreat

Author: T. Inoue, N. Izumi, J.S. Scheingross, Y. Hiramatsu, S. Tanigawa, T. Sumner

Issue&Volume: 2023-05-26

Abstract: Waterfalls are among the fastest-eroding parts of river networks, but predicting natural waterfall retreat rates is difficult due to multiple processes that can drive waterfall erosion. We lack data on how waterfall height influences the mechanism and rate of upstream waterfall retreat. We addressed this knowledge gap with experiments testing the influence of drop height on waterfall retreat. Our experiments showed that shorter waterfalls retreat up to five times faster than taller waterfalls, when bedrock strength, sediment supply, and water discharge are constant. This retreat rate difference is due to a change in the erosion mechanism. Short waterfalls retreat by the formation of several small, rapidly eroding bedrock steps (i.e., cyclic steps), whereas tall waterfalls tend to form large bedrock plunge pools where lateral plunge pool erosion allows headwall undercutting and subsequent waterfall retreat. Because waterfall height can be partially set by the waterfall formation mechanism, our results highlight that the rate of waterfall retreat and subsequent landscape evolution can be modulated by the processes that form waterfalls.

DOI: 10.1130/G51039.1

Source: https://pubs.geoscienceworld.org/gsa/geology/article-abstract/doi/10.1130/G51039.1/623709/Waterfall-height-sets-the-mechanism-and-rate-ofredirectedFrom=fulltext