Brookings Triangulation

GNSS Survey

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Roque Ruiz 

The aim of this project was to identify any observational errors and the differences found between modern day conventional triangulation methods (GNSS Baselines) and the older theodolite methods of triangulation used by J.S. Brooking in the 1800s. 

In 1874-1875 Surveyor Brooking conducted a triangulation survey from Rockingham Baseline to Champion Bay (Geraldton) parallel to the coast. This included over 100 triangles with some 120 trigs the only control being the Rockingham Baseline. This was one of the earliest major surveys of the new Colony and an attempt to accurately map the landmass of WA (The Australian Surveyor, June 1975, Vol. 27, No. 2). Up to this point only the coast had been mapped to any degree of accuracy by expedition ships such as Flinders in the early 1800s.

Large differences between the original survey and the GNSS re-survey are expected due to the transformation of datum parameters over the last 100 years as well as tectonic plate movements, in which Australia sits on the Indo-Australian plate, one of the fastest moving tectonic plates in the world (up to 7cm north per year).