Graphically interpreting how incision thresholds influence topographic and scaling properties of modeled landscapes


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Date

2021-12-13

Publication Type

Journal Article

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yes

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Abstract

We examine the influence of incision thresholds on topographic and scaling properties of landscapes that follow a landscape evolution model (LEM) with terms for stream-power incision, linear diffusion, and uniform uplift. Our analysis uses three main tools. First, we examine the graphical behavior of theoretical relationships between curvature and the steepness index (which depends on drainage area and slope). These relationships plot as straight lines for the case of steady-state landscapes that follow the LEM. These lines have slopes and intercepts that provide estimates of landscape characteristic scales. Such lines can be viewed as counterparts of slope-area relationships, which follow power laws in detachment-limited landscapes but not in landscapes with diffusion. We illustrate the response of these curvature-steepness index lines to changes in the values of parameters. Second, we define a Peclet number that quantifies the competition between incision and diffusion, while taking the incision threshold into account. We examine how this Peclet number captures the influence of the incision threshold on the degree of landscape dissection. Third, we characterize the influence of the incision threshold using a ratio between it and the steepness index. This ratio is a dimensionless number in the case of the LEM that we use and reflects the fraction by which the incision rate is reduced due to the incision threshold; in this way, it quantifies the relative influence of the incision threshold across a landscape. These three tools can be used together to graphically illustrate how topography and process competition respond to incision thresholds.

Publication status

published

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Volume

9 (6)

Pages / Article No.

1545 - 1561

Publisher

Copernicus

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Edition / version

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Software

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03798 - Kirchner, James W. (emeritus) / Kirchner, James W. (emeritus) check_circle

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