While floods and landslides have killed 30 people and left over 160 people missing in southwest China's Sichuan Province, heavy rainfall over the past week has threatened the ruins of a major earthquake that razed the same region five years ago.

The ruins of the 2008 earthquake-devastated old town of Beichuan in a ravine between two mountains have been partially submerged, said Han Guijun, an official in charge of the preservation projects of the old town of Beichuan Qiang Autonomous County.

The recent severe rainfall caused the old town to become waterlogged with some areas under seven meters of water. Sites, including a cemetery for earthquake victims, have been submerged due to the overflowing Jianjiang River that runs through the old town, Han said.

Some people questioned the preservation of the ruins, arguing that hundred of millions of yuan were wasted and could have been spent on other things, such as hospitals.

But local authorities insisted that preserving the earthquake ruins is necessary, despite the recent flooding.

Han said investment for an earthquake memorial hall and other preservation projects cost 470 million yuan (76.26 million U.S dollars).

"Thanks to a series of protection measures adopted in and nearby the old town, the ruins of Beichuan have largely survived the rain-triggered flood," said Han.

The preservation project included dams in an attempt to protect against mud-rock flows, landslides and flooding, which frequently occurred in the town after the quake.

About 20,000 Beichuan residents were declared dead or missing after the 8.0-magnitude Wenchuan earthquake in May 2008 and thousands of victims were buried in the ruins.

Rather than rebuilding the town, central and local governments relocated earthquake survivors and built a new Beichuan town, preserving the old town as quake relics as a lasting memorial for quake survivors to mourn the deceased.

Since May 2010, the old town has been open to the public.