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Research Article

Investigating the Interplay of Permeability and Roughness on Patchy Vegetated Hillslopes in Silico

Authors
  • Octavia V Crompton orcid logo
  • Gabriel George Katul orcid logo (Duke University)
  • Sally Thompson orcid logo

Abstract

On hillslopes with patchy vegetation cover, vegetation is a significant factor controlling surface hydraulic and hydrological properties.  Soil permeability is often greater within vegetated areas than in surrounding bare soil areas, leading to the redistribution of rainfall from bare, runoff-generating areas to permeable, vegetated areas. While many studies have examined the hydrological consequences of permeability contrasts, the hydrodynamic effects of greater surface roughness in vegetated patches compared to bare areas remain under-investigated. The role of roughness is not obvious: greater roughness in vegetated patches provides greater resistance to flow, slowing water movement and thus extending the time frame over which infiltration can occur. However, greater roughness may also cause partial blocking and flow diversion, reducing the volume of water traversing vegetated areas, a mechanism that could reduce rainfall redistribution to these sites. 

To differentiate the roles of spatially-varying roughness and permeability on rainfall redistribution, the two-dimensional Saint Venant Equations are employed to model the hydrologic outcomes of permeability and roughness contrasts under varying rainfall intensities.The simulations consider the dynamically interesting case of an idealized vegetated patch surrounded by runoff-generating unvegetated areas. The model results indicate that greater resistance causes flow diversion around vegetation. However, vegetative resistance only reduces rainfall redistributed to the vegetation under the specific conditions of low rainfall intensity and high soil permeability. Otherwise, prolonged ponding during the recession period, due to greater vegetative resistance, creates additional time for infiltration, compensating for increased flow diversion around the vegetation. 

Keywords: Source-Sink Dynamics, Surface Roughness, Vegetation Spatial Pattern, Hydrological Connectivity

How to Cite:

Crompton, O. V., Katul, G. G. & Thompson, S., (2025) “Investigating the Interplay of Permeability and Roughness on Patchy Vegetated Hillslopes in Silico”, ARC Geophysical Research 1(1): 10. doi: https://doi.org/10.5149/ARC-GR.1384

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Funding

Name
National Science Foundation
Funding ID
EAR-PF-1952651
Name
National Science Foundation
Funding ID
NSF-AGS-2028644
Name
U.S. Department of Energy
Funding ID
DE-SC0022072

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Published on
2025-06-30

Peer Reviewed