The simulation of water uptake by vegetation and its impact on slope stability using an image – based model of plant root architecture

Shang, Kai 2016. The simulation of water uptake by vegetation and its impact on slope stability using an image – based model of plant root architecture. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

The overall aim of this research is to develop a new root-image based approach to modelling water uptake by plants. The approach developed employs a digitized image of the root zone to determine an ‘effective root density ratio’ that is subsequently used to yield a spatially variable sink term. The moisture flow model chosen is based on Richards’ Equation added a sink term to facilitate inclusion of a water uptake model (i.e. 1D, 2D and 2D axisymmetric format). A numerical solution was achieved via the finite element method for spatial discretisation along with a finite difference time-marching scheme. The numerical evaluation of the root density ratio was coded in Matlab. The resulting values were then used to define the spatial variation of the sink term within the finite element code. Initial applications of the new model operating in a one-dimensional mode provided some confidence with respect to the implementation of the new image-based root density approach to simulate moisture migration patterns beneath a uniform cover of vegetation. A new two-dimensional axi-symmetric form of the model was then developed and applied to simulate moisture migration near established trees. The model was validated by direct comparison to the field measurements recorded. The study provided an assessment of the significance of water content (and therefore suction) changes on the stability of unsaturated soil slopes. Two typical root architectures were considered to investigate the influence of root architecture on slope stability. In particular, effects of root architecture were emphasized. In conclusion, a new root-image based approach to modelling water uptake by plants has been developed. In general, it is hoped that the current research has provided a useful further contribution on modelling water-uptake process and on the overall assessment of slope stability.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Engineering
Subjects:	S Agriculture > SB Plant culture T Technology > TA Engineering (General). Civil engineering (General)
Uncontrolled Keywords:	Root Water Uptake; Modelling Water Uptake by Plants; A root-image based approach; Slope stability; Trees; Simulation.
Date of First Compliant Deposit:	2 February 2017
Last Modified:	03 Nov 2021 09:30
URI:	https://orca.cardiff.ac.uk/id/eprint/97986

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