Marine National Park Headquarters

“Coastal drift” refers to the movement of sand particles and sediments along the shoreline under the influence of waves and ocean currents. Because waves often approach the shore at an angle, they generate currents that run parallel to the coastline, carrying sand and gravel in the same direction. This process is known as “longshore drift.”

In the waters of Dongsha Atoll National Park and Penghu South Four Islands National Park, the phenomenon of coastal drift is particularly evident. Influenced by monsoons, tides, and shifting ocean currents, the positions of sandbars and the shapes of coastlines change over time. Some areas may experience sediment accumulation, while others may undergo erosion.

This natural process of geomorphological change is an integral part of coastal ecosystems. However, if human-made structures disrupt the flow of drifting sediments—such as improperly constructed seawalls or harbors—localized coastal erosion may intensify, potentially impacting coral reefs and intertidal habitats.

Through long-term observation and photographic documentation, the Marine National Park Headquarters continues to monitor shoreline changes. Scientific monitoring data serve as the basis for management and conservation decisions, helping to prevent irreversible impacts on coastal landforms and ecosystems caused by overdevelopment.