Analyzing the spatio-temporal correlation between tide and shipping behavior at estuarine port for energy-saving purposes

Estuarine ports account for more than 80% of world ports. Considering the large portion of ships depart and arrive at estuarine ports worldwide, using current and tide to departure and arrive at the estuarine ports can help to save energy and reduce fuel consumption and pollution emissions. To better understand to what extent ships take and against the tide when entering and leaving estuarine port for energy-saving purposes, this study collected AIS data of ships in the Pearl River Estuary region in 2022 and fused it with the simulated current data to unveil the ship behavior patterns. It is found that most of the ships sailed against tide among the 225,333 ships entered and left the harbor in 2022. 75-76% of the ships choose to enter the harbor against current, 9% choose to enter the harbor in transverse current, and only 15-16% choose to take tide. In terms of outbound ships, the proportions of ships sailed against tide equals to the proportion take tide, each took 41-45%, 11-15% sailed in the transverse current direction. Our result revealed that the outbound ships is better at take tide than inbound ships, especially at the tide with a speed higher than 0.6 m/s. The methods demonstrated in this study can be adapted and applied to other estuarine ports to understand the impact of the tide on shipping energy consumption. Future studies should focus on increasing the energy efficiency of ships by better planning the shipping schedule and taking advantage of the tide while leaving and entering the ports.