GNSS at NSW tide gauges... of CORS!

Tide gauges measure and record the water level over time. The tide gauge records available from Fort Denison, Sydney Harbour and the Pilot Station, Newcastle in New South Wales (NSW) are two of the longest continuous records in the southern hemisphere. By virtue, these are of considerable national and international importance in relation to sea level rise and climate change research. For the precise determination of any sea level change, it is fundamental to know whether or not the land upon which the tide gauge is located is actually moving. Is the sea level rising or the land falling? Global Navigation Satellite System (GNSS) Continuously Operating Reference Stations (CORS) are the ideal candidates to provide accurate and continuous measurements of land movement at tide gauge locations. This article outlines the high value of augmenting tide gauge records with GNSS CORS. It also provides an insight into the considerable difficulties encountered in the installation of such CORS in sensitive, heritage-listed and harsh marine environments. We focus on the recent construction of two CORS at the aforementioned tide gauges, which have been integrated into the CORSnet-NSW network to deliver high-accuracy positioning infrastructure for NSW