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Influence of Spatial Rainfall Gradients on River Longitudinal Profiles and the Topographic Expression of Spatio-temporally Variable Climate in Mountain Landscapes
  • Joel S Leonard,
  • Kelin X Whipple
Joel S Leonard
Arizona State University, Arizona State University

Corresponding Author:joel.leonard@asu.edu

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Kelin X Whipple
Arizona State University, Arizona State University
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Mountain landscapes have dynamic climates that, together with tectonic processes, influence their topographic evolution. While spatio-temporal changes in rainfall are ubiquitous in these settings, their influence on river incision is understudied. Here, we investigate how changes in rainfall pattern should affect both the steady state form and transient evolution of river profiles at the catchment scale using the stream power model. We find that spatially varied rainfall can complicate steady state relationships between mean rainfall, channel steepness and fluvial relief, depending on where rainfall is concentrated in catchments. As a result, transient profile adjustments to climate changes may proceed contrary to typical expectations, which can ultimately affect the apparent sensitivity of landscapes and erosion rates to climate. Additionally, changes in rainfall pattern cause inherently multi-stage transient responses that differ from responses to uniform changes in rainfall. These results have important implications for detecting transient responses to changes in rainfall pattern (and more broadly climate), and for interpreting of landscape morphometrics above and below knickpoints. Further, we find that disparate responses by rivers that experience different rainfall conditions, particularly trunk and tributary rivers, are an important factor in understanding catchment-wide responses, and accounting for such disparities may be important for detecting and quantifying landscape sensitivity to variations in climate. Lastly, we show how explicitly accounting for rainfall patterns in channel steepness indices, and thus variations in erosional efficiency, has potential to help address challenges related to spatially variable rainfall patterns and advance understanding of landscape sensitivity to climate in mountain settings
05 Dec 2022Submitted to ESS Open Archive
05 Dec 2022Published in ESS Open Archive
Dec 2021Published in Journal of Geophysical Research: Earth Surface volume 126 issue 12. 10.1029/2021JF006183