Rainfall spatial-heterogeneity accelerates landscape evolution processes
Details
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State: Public
Version: Final published version
License: CC BY 4.0
UNIL restricted access
State: Public
Version: Final published version
License: CC BY 4.0
Serval ID
serval:BIB_786DE613A955
Type
Article: article from journal or magazin.
Collection
Publications
Institution
Title
Rainfall spatial-heterogeneity accelerates landscape evolution processes
Journal
Geomorphology
ISSN
0169-555X
Publication state
Published
Issued date
10/2021
Peer-reviewed
Oui
Volume
390
Pages
107863
Language
english
Abstract
Catchment hydro-morphological response is mainly conditioned on rainfall properties, such as rainfall intensity, storm duration and frequency, and the timing of these events. Rainfall spatial variability is likewise a major determinant affecting streamflow, erosion, and sediment transport, and is explored largely in the context of heavy rain triggering floods and fast morphological changes on hillslopes and in channels. In this study, we examine how the spatial structure of rainfall influences landscape evolution at the catchment scale over hundreds of years. To achieve this, multiple realizations of hourly rainfall fields, each differing only by their spatial distribution but identical in all other respects, were simulated using a weather generator. The impact of storm spatial-heterogeneity on the catchment morphology was then assessed with a landscape evolution model (CAESAR-Lisflood). A virtual “open-book” type catchment was used for this numerical experiment. The mean streamflow and low-flows remained the same while the magnitude of the annual peak streamflow increased by up to 12% in response to higher rainfall spatial heterogeneity. However, the erosion and deposition rates significantly increased (up to 50%) and the net erosion and deposition areas changed (increased by up to 9% and decreased by 13.5%, respectively) when the rain became less uniform in space. Furthermore, new gullies were found to be longer, deeper, and more branched in response to increased rainfall heterogeneity. The results suggest that heterogeneity in rainfall spatial patterns speeds up landscape development, even when rainfall volumes and temporal structures are the same. This implies that the spatial structure of rainfall may have more of an influence on catchment morphology at long time scales than previously thought.
Keywords
Earth-Surface Processes
Open Access
Yes
Create date
09/08/2021 15:56
Last modification date
15/11/2022 16:04