The northwestern seashore, from Taoyuan County to Hsinchu County, is retreating as a result of human activity, the Ministry of Economic Affairs’ Central Geological Survey (CGS) said.
The latest survey report, released last year, showed that the coastline south of Datan Village (大潭) in Guanyin Township (觀音), Taoyuan County, and the section of coastline from Hukou Township (湖口), Hsinchu County, to Siangshan District (香山) in Hsinchu City was retreating.
CGS Director Lin Chao-tsung (林朝宗) said such erosion could have been caused by manmade structures along the coast, such as the Datan Power Station and the Hsinchu Fishing Harbor.
While some sections of Taiwan’s coastline are retreating, the report shows there are also sections of shoreline pushing outward into the sea.
As manmade structures change the course of rivers, the sand and soil carried downstream settles only on the banks of a river mouth without manmade structures, making coastlines shrink on one side, but grow on the other, he said.
Under normal circumstances, the coastline should be growing evenly, Lin said.
The CGS said the government should take a series of measures to prevent extensive shrinking of coastlines.
Although concrete blocks are now piled along coastlines to prevent erosion, Lin said that concrete blocks would only work for a limited period of time and erosion would still occur sooner or later.
He said the best way to prevent erosion would be to make better plans before building anything along the coast.
The latest report released by the Ministry of the Interior’s Construction and Planning Agency showed that as of last year, Taiwan had 1,321.9km of coastline, or 3km more than in 2008. However, this was the result of manmade structures, as cemented coastline — including embankment, harbor and reclaimed lands — had grown 3km since 2008.
At the moment, 55.5 percent of Taiwan’s coastline has been cemented, about 0.1 percent more than in 2008.
As climate change progresses, sea levels continue to rise, Lin said, and the concept of reclaiming land from the sea should be changed, since experts are becoming more uncertain about how long manmade structures will last.