Modeling Soil, Hillslope, Landscape Evolution

“Simplicity you can argue for.”

10.1 Brief Outline

  1. Numerical model building
    1. Purpose / Goals
    2. Identification of most key factors/variables
    3. Assumptions and methods
    4. Test results
    5. Verification and data mined data

Describe the purpose: The purpose of this section is to create a quantitative framework, a model, to explore the relationship between bioturbation, erosion, and particle size distribution and their collective impact on soil profile and landscape development.

Identify the key variables: erosion rate, mixing rate, local vs. non-local ratio, change in animal activity with depth, bulk density, and soil property characteristics.

Describe methods [very WIP, considering using python and landlab for portions, need to investigate further]

10.2 Important equations / variables

Hill slope creep \[ \frac{dz}{dt}=D\frac{d^2z}{dx^2} \]

Soil mixing \[ \frac{dy}{dz}=D(z)\frac{dy}{dz}+\frac{dz}{dt}\frac{dy}{dz} \]

Diffusion coefficient \[ D(z)=D_0e^{-z/z_b} \] Soil Production \[ P = e^{-az} \]

10.3 Resources

Dissertation using landlab: Mahmoudi, M. (2018). Comparing model predictions of hillslope sediment size distribution with field measurements (Doctoral dissertation, San Francisco State University).

10.4 Notes

  • Use landlab to simulate hillslope evolution under different earthworms / bioturbation types? Broaden to landscape scale? Include sediment contribution to streams?

  • Simulate Mima mound creation by pocket gophers using a landlab module?