Operational monitoring systems available at the three sites

Tide gauges can capture sea level variability on multiple timescales, from high frequency events like waves, tides and tsunamis, to seasonal and interannual changes and the longer-term trends associated with Climate Change. However, financial constraints dictate that they are often maintained to lower standards than the stringent accuracy requirements demanded by the IOC-UNESCO’s Global Sea Level Observing System (GLOSS) for monitoring sea level rise. In addition, a sparsity of Global Navigation Satellite System (GNSS) receivers at the coast means that there are large uncertainties in rates of land motion at tide gauges, which also hampers the estimation of long-term sea level trends. Task 5.1.1 has devised prototype low maintenance tide gauge systems, powered by renewable energy and which monitor both land motion and sea level using novel techniques such as ground-based GNSS Interferometric Reflectometry (GNSS-IR). These systems eliminate the need for costly ongoing levelling exercises and also incorporate customisations to local monitoring needs, such as sensors for lightning detection and wave height. Despite a number of unforeseen setbacks, these prototype systems are now operating at 2 locations in the Mediterranean Sea and a third system is in transit to Colombia for installation by local stakeholders who have been trained in the installation methodology by the WP5 team. It is hoped that there is potential to advance these technological solutions as a global standard, via the GLOSS community.