Multi-applications of GPS for Hydrographic Surveys

A multi-antenna GPS system was designed and applied mainly to the so-called ‘tideindependent’ bathymetric measurements. It aimed at improving the accuracy achieved by the traditional technique, in which the tidal observations required were made at the tide gauges along the coast. The attitude parameters of the vessel, estimated by the GPS system, can also be introduced to the corrections for the bathymetric measurements. The assessment using different correction modes, based on GPS solutions and applied to the bathymetric measurements, indicated that the measurement quality has been significantly improved by the tide-independent technique. The accuracy of bathymetric measurements has shown the improvement of up to 47%, and fully satisfied to the first-order standard of the international hydrographic survey. The offshore tidal observations, relied on the vessel-based GPS system, were also effectively made by the vertical component of the GPS solutions. The average agreement between the observations from the GPS solutions and tide gauge records has found to be better than 3 cm, based on the field tests carried out nearby the Hsinchu Harbor located at the northwestern coast of Taiwan.