People ride a modified "tuk-tuk," or motor tricycle taxi, through a flooded street in Bangkok, Thailand, November 7, 2011.
People ride a modified "tuk-tuk," or motor tricycle taxi, through a flooded street in Bangkok, Thailand, November 7, 2011.

Floodwaters continued to threaten central Bangkok Monday even as clean-up efforts begin in some areas north of the city where waters have receded.

Authorities said the death toll in Thailand's worst floods in a half century has gone over 500, with drowning blamed for most of the deaths. Prime Minister Yingluck Shinawatra said her cabinet will meet Tuesday to begin considering a reconstruction plan valued at more than $3 billion.

For many Bangkok residents, transportation remains the biggest problem, with people turning to boats, buses and military vehicles to make their way through affected areas.

"It took me six hours to get from Nava Nakorn to Mo Chit area," said Bangkok resident Saitarn Siriatcharanon.

She said the trip normally takes her just one hour.

Maureen Birmingham, head of the local office of the World Health Organization, said relief efforts are complicated because different parts of Thailand are at very different stages of flood threat and recovery.

"There are sort of three situations in the country," she said. "There is the areas that, for example the north, that are already looking at early recovery and cleaning up; there is areas acutely, just recently affected; and then there is areas that are in this protracted state. So, you know, with each of those areas, different activities are happening, different risks, different issues. And then there is the areas where flood waters may go."

She said government officials are meeting with the United Nations and other partners to begin planning recovery efforts.

The flooding began in northern Thailand in July with two typhoons and unusually heavy monsoon rains that swamped as much as 10 percent of the country.

The vast sea of water gradually moved southward until it reached Bangkok, where authorities hope an elaborate network of flood barriers and canals can channel it into the sea without flooding the city.

Despite the barriers, residential neighborhoods and several large industrial parks on Bangkok's northern suburbs have been flooded, forcing officials to sharply downgrade the country's short-term economic prospects.

Some information for this report was provided by AP, AFP and Reuters.