英国杜伦大学James Buckley和英国牛津大学Louise J. Slater团队，研究了美国河流几何形状的水文和岩性控制。2024年3月27日出版的《地质学》杂志发表了这项成果。

基岩河流通常被认为比冲积河流的河道更陡峭、更狭窄。然而，人们对基岩河流特征的了解，在很大程度上是基于特定气候和高地地区的小样本。

该研究团队首次对1274个不同气候梯度地点的基岩和冲积河道特征进行了系统评估。研究评估了基岩河道的宽度、宽深比和坡度是否与冲积河道不同，以及这些差异在多大程度上与流域面积、年平均流量(Q_MAF)、粒度和岩性相关。

结果发现，基岩河道在所有流域都存在。同一流域，基岩河道比冲积河道更宽、更陡。它们也有更高的年平均降水量和Q_MAF，这可能与宽度增加有关。考虑到Q_MAF的差异，基岩和冲积河道具有相似的水力规模。岩性以相似的方式影响这两种类型的河道，沉积岩性的河道比火成—变质岩性的河道更宽，坡度更小。总的来说，该研究提出了关于基岩河道演变的新问题，并为更准确的景观演变建模铺平了道路。

附：英文原文

Title: Bedrock rivers are steep but not narrow: Hydrological and lithological controls on river geometry across the USA

Author: James Buckley, Rebecca A. Hodge, Louise J. Slater

Issue&Volume: 2024-03-27

Abstract: Bedrock rivers are commonly expected to have steeper and narrower channels than alluvial rivers. However, understanding of bedrock river characteristics has largely been based on small samples of sites in specific climates and upland locations. We provide the first systematic assessment of bedrock and alluvial river channel characteristics for 1274 sites across a broad climatic gradient. We assess whether the width, width-to-depth ratio, and slope of bedrock channels differ from those of alluvial channels and the extent to which these differences are correlated with drainage area, mean annual flow (Q_MAF), grain size, and lithology. We find that bedrock channels occur at all drainage areas. For the same drainage area, bedrock channels are wider and steeper than alluvial channels. They also have a higher mean annual precipitation and hence Q_MAF, which likely causes the increased width. After accounting for differences in Q_MAF, both bedrock and alluvial channels have similar hydraulic scaling. Lithology affects both types of channels in a similar way, with channels on sedimentary lithologies being wider and less steep compared to those on igneous-metamorphic lithologies. Overall, our findings raise new questions about the evolution of bedrock river channels and pave the way for more accurate landscape evolution modeling.

DOI: 10.1130/G51627.1

Source: https://pubs.geoscienceworld.org/gsa/geology/article-abstract/doi/10.1130/G51627.1/637053/Bedrock-rivers-are-steep-but-not-narrowredirectedFrom=fulltext