Excess pore water pressure due to ground surface erosion

•The pore water pressure in an aquifer under an eroding surface with an initial unsaturated zone is found in closed form.•A method based on the Laplace transform is used to handle the moving upper boundary of the domain.•Over an impermeable layer the pressure decreases for low erosion rates.•For hig...

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Bibliographic Details
Published in:Applied Mathematical Modelling 2018-09, Vol.61, p.72-82
Main Authors: Gagniere, Steven, Llewellyn Smith, Stefan G., Yeh, Hund-Der
Format: Article
Language:English
Subjects:
Aquifers
Boost theorem
Erosion
Erosional unloading
Fluxes
Groundwater flow
Laplace transform
Laplace transforms
Pore water pressure
Pressure
Water
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Summary:•The pore water pressure in an aquifer under an eroding surface with an initial unsaturated zone is found in closed form.•A method based on the Laplace transform is used to handle the moving upper boundary of the domain.•Over an impermeable layer the pressure decreases for low erosion rates.•For high erosion rates it, the pressure can increase temporarily before decaying. The Laplace transform is applied to solve the groundwater flow equation with a boundary that is initially fixed but that starts to move at a constant rate after some fixed time. This problem arises in the study of pore water pressures due to erosional unloading where the aquifer lies underneath an unsaturated zone. We derive an analytic solution and examine the predicted pressure profiles and boundary fluxes. We calculate the negative pore water pressure in the aquifer induced by the initial erosion of the unsaturated zone and subsequent erosion of the aquifer.
ISSN:0307-904X
1088-8691
0307-904X
DOI:10.1016/j.apm.2018.03.041