Local authorities in Wuhan, Central China's Hubei Province said that the low terrain and unusual weather in the area are to blame for serious flooding, after the public raised questions over enormous previous investment in a drainage system.

An official from Wuhan Water Authority explained at a news conference on Wednesday that Wuhan used to be a marshland, leaving the city with poor drainage conditions. He added that the El Nino phenomenon has also caused unusually heavy rain this year.

"Previously, our country's top priority was economic development, so we set a low standard for the construction of the urban drainage system. Flooding would occur if heavy rain broke any one of those standards," he noted.

An overnight storm following days of rain paralyzed traffic, cut power and water supplies, and trapped people in their homes in many parts of Wuhan. Approximately 757,000 people in 12 districts of Wuhan have been affected by flooding, with a current toll of 14 dead and 1 missing.

The serious flooding prompted media and the public to raise questions over the city's previous huge investment in its drainage system.

In 2013, Wuhan authorities spent 13 billion yuan ($1.9 billion) to build a drainage system that promised to put an end to flooding problems.

Wang Xinyi, a student at Beijing Normal University, sent an open letter to the Wuhan Water Authority demanding that they publicize the details of the drainage system expenditures, news site thepaper.cn reported, adding that authorities pledged to reply within 15 working days after they receive the letter.

Local officials said the city's traffic network will be back to normal by Friday.