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

Featherstone, W.E.; Penna, N.T.; Filmer, M.S.; Williams, S.D.P. ORCID: https://orcid.org/0000-0003-4123-4973. 2015 Nonlinear subsidence at Fremantle, a long-recording tide gauge in the Southern Hemisphere. Journal of Geophysical Research: Oceans, 120 (10). 7004-7014. https://doi.org/10.1002/2015JC011295

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Abstract/Summary

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.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	https://doi.org/10.1002/2015JC011295
ISSN:	21699275
Additional Keywords:	geodesy; vertical land motion; sea level change
NORA Subject Terms:	Marine Sciences
Date made live:	28 Oct 2015 09:33 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/512107

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