Damming large numbers of rivers and unrestrainedly taking gravel from the river beds combine to strike a double blow at the coastline's ability to resist erosion; and subsidence of the land itself further compounds the problem.
河川廣建水庫與河床濫採沙石，對海岸國土遠近交逼；內陸地層下陷，則配合澎湃的海浪，對之內外夾擊。