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Nonlinear subsidence at Fremantle, a long-recording tide gauge in the Southern Hemisphere

Lookup NU author(s): Dr Nigel Penna

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This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND).


Abstract

A combination of independent evidence (continuous GPS, repeat geodetic leveling, groundwater abstraction, satellite altimetry, and tide gauge (TG) records) shows that the long-recording Fremantle TG has been subsiding in a nonlinear way since the mid-1970s due to time-variable groundwater abstraction. The vertical land motion (VLM) rates vary from approximately -2 to -4 mm/yr (i.e., subsidence), thus producing a small apparent acceleration in mean sea level computed from the Fremantle TG records. We exemplify that GPS-derived VLM must be geodetically connected to the TG to eliminate the commonly used assumption that there is no differential VLM when the GPS is not colocated with the TG. In the Perth Basin, we show that groundwater abstraction can be used as a diagnostic tool for identifying nonlinear VLM that is not evident in GPS time series alone.


Publication metadata

Author(s): Featherstone WE, Penna NT, Filmer MS, Williams SDP

Publication type: Article

Publication status: Published

Journal: Journal of Geophysical Research: Oceans

Year: 2015

Volume: 120

Issue: 10

Pages: 7004–7014

Print publication date: 01/10/2015

Online publication date: 09/10/2015

Acceptance date: 06/10/2015

Date deposited: 13/11/2015

ISSN (print): 2169-9275

ISSN (electronic): 2169-9291

Publisher: Wiley-Blackwell Publishing, Inc.

URL: http://dx.doi.org/10.1002/2015JC011295

DOI: 10.1002/2015JC011295


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