Coastal sea level monitoring in indonesia: Connecting the tide gauge zero to leveling benchmarks

Abstract

After the tsunami in 2004, Badan Informasi Geospasial (BIG), Indonesia, and its international partners established a large network of coastal tide gauge stations for the Indonesian Tsunami Early Warning System (InaTEWS). In the frame of the German Indonesian Tsunami Early Warning System (GITEWS), Germany donated ten tide gauge stations equipped with geodetic GNSS receivers and recently three more stations for subsidence monitoring. This network establishes a backbone for dedicated sea level research projects, for tsunami warnings, for subsidence monitoring and for the unification of the national height reference system. The radar sensors of the tide gauges establish long-term control points to connect the tide gauge zero to the leveling benchmarks and thus to the local height system. This paper evaluates the individual station offsets of the radar gauge zero, which is essential to connect the measured sea level to the vertical control network (VCN).