Measuring the imprint of orographic rainfall gradients on the morphology of steady-state numerical fluvial landscapes
ABSTRACT We explore the imprint of spatial rainfall patterns on steady‐state landscapes with uniform rock uplift rate. A two‐dimensional (2D) orographic precipitation module is incorporated into the CHILD numerical landscape evolution model to provide a quantitative tool for exploring the co‐evoluti...
Saved in:
Published in | Earth surface processes and landforms Vol. 40; no. 10; pp. 1334 - 1350 |
---|---|
Main Authors | , , |
Format | Journal Article |
Language | English |
Published |
Bognor Regis
Blackwell Publishing Ltd
01.08.2015
Wiley Subscription Services, Inc |
Subjects | |
Online Access | Get full text |
Cover
Loading…
Summary: | ABSTRACT
We explore the imprint of spatial rainfall patterns on steady‐state landscapes with uniform rock uplift rate. A two‐dimensional (2D) orographic precipitation module is incorporated into the CHILD numerical landscape evolution model to provide a quantitative tool for exploring the co‐evolution of rainfall patterns and fluvial topography. Our results suggest that network organization and planform morphology are strongly impacted by rainfall patterns. Rainfall gradients that are perpendicular to a mountain range front produce narrower watersheds because channels show a tendency to flow along the rainfall gradient, rather than across it. The change in watershed shape is evidenced by smaller values of the exponent on distance in Hack's law and a less peaked width function. Narrower watersheds also lead to an increase in the valley spacing ratio and constrain trunk channels to follow a more direct path to the mountain front. Rainfall gradients also influence the distribution of topography across a watershed. Channel profiles record rainfall patterns in both the channel concavity and the channel steepness index (ksn). Across short tributaries along which rainfall rate changes little, ksn decreases systematically with tributary‐averaged rainfall rate. The hypsometric integral (HI), which increases with the amount of topography that is at relatively high elevations within a watershed, is negatively correlated with the profile concavity of the trunk channel. High rainfall rates at the ridge top lead to mainstem channels that have relatively low concavity, and watersheds with relatively higher HI in comparison with landscapes that have uniform rainfall. Finally, we contrast the impacts of rainfall patterns on landscape morphology with those resulting from a linear rock uplift gradient and uniform rainfall. Uplift patterns may have a similar impact on landscape morphology as rainfall gradients, making it challenging to decipher the relative roles of climate and tectonics on landscape evolution without a quantitative assessment of morphologic parameters. Copyright © 2015 John Wiley & Sons, Ltd. |
---|---|
Bibliography: | istex:48AF0F26B811DE7826D93665E59F51932B6C1AC9 ark:/67375/WNG-H0R378X5-3 ArticleID:ESP3723 ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0197-9337 1096-9837 |
DOI: | 10.1002/esp.3723 |