Land subsidence along the high-speed railway in central Taiwan was alleviated somewhat last year as higher rainfall replenished the groundwater, but the Taiwan High Speed Rail Corp (THSRC) said the problem of sinking land has not disappeared.

Citing subsidence monitors, THSRC said abundant rainfall in 2012 and 2013 helped restore some of the groundwater tapped from the largely rural areas above which the elevated railway runs, but while the sinking has slowed down, it remains a concern.

In Changhua county, the land sank by 6.6 centimeters in 2011 and 4.3 cm in 2012. The number decreased further to 3.5 cm last year.

Two monitors in neighboring Yunlin county showed similar degrees of slowdown, corresponding with an increase in precipitation in the areas over the past two years, the company said.

One of the monitors, located in Yunlin's Tuku township, showed rainfall increased from 799 milliliters in 2011 to 1,666 ml in 2012. It further increased to 2,262 ml last year.

But a resolution to the problem cannot rely on the mercy of mother nature. Some wells along the high-speed railway in Changhua and Yunlin have been sealed in recent years, but it is not enough to end the subsidence that could force trains to operate at lower speeds or even shorten the lifespan of the railway if left as is.

THSRC spokesman Ted Chia called on the government to take the subsidence issue more urgently, as any solution would require the cooperation of local farmers and industries — both heavy users of groundwater — as well as the central and local governments.

Opened in early 2007, the 345-kilometer high-speed rail carries an average of 130,000 passengers per day. The railway is elevated all the way from Changhua to its southern terminus in Zuoying, Kaohsiung city, a distance of over 150 km.