XI'AN - More than 12 million tourists are expected to go this year to the International Horticultural Exposition, which began in Xi'an, capital of Northwest China's Shaanxi province, on Thursday.

Dancers from Burundi perform at the opening ceremony of the International Horticultural Exposition in Xi'an, capital of Shaanxi province, on Thursday. [Yuan Jingzhi / for China Daily] Click for more photos

The exposition will last for 178 days, until Oct 22 this year.

In accordance with its motto, "eternal peace and harmony between nature and mankind, nurturing the future earth", the exposition is aimed at presenting mankind's ability to find ways to achieve economic growth without doing great harm to the environment, Zhao Zhengyong, governor of Shaanxi province and president of the organizing committee, said at the opening ceremony.

The exposition park is in the city's Chanba Ecological District.

As recently as 2004, the Chanba district was a garbage dump and two nearby rivers were heavily polluted, Ma Yaofeng, a professor at the college of tourism and environment in Shaanxi Normal University, told the Beijing News.

Yet, with a few years of work, the district was cleaned up, making Xi'an better able to promote its environmental tourism industry, Ma said.

According to the organizing committee, 109 cities and institutions from China and abroad have set up pavilions in the exposition park.

Marie-Louise Ronnmark, mayor of Umea city in Sweden, said the event will give cities a place to teach each other ways to protect the environment of urban places, whether that be done through garbage recycling or reducing air pollution.

She said Umea city started a green technology project with Xi'an in 2010, and the two cities will work together to encourage other places in the next three years to begin using technologies that consume relatively little energy.

"I have visited Xi'an four times," Ronnmark said. "I am happy to see more and more trees and flowers have been planted thanks to the exposition".

Dancers perform at the opening ceremony of the International Horticultural Expo 2011 in Xi'an, capital of Northwest China's Shaanxi province, April 28, 2011. The opening ceremony lasted less than an hour to embody the Expo's theme of environmental-friendliness. Expo lasts about six months to Oct 22. [Photo/Xinhua] Click for more photos

On Thursday, the high temperature in the city was 32 C. Some visitors said they went to the horticultural exposition at the risk of succumbing to sunstroke.

"We queued for more than three hours on such a hot day to get into the park," said Qiu Lijun, a 56-year-old retired worker from Chengdu, Southwest China's Sichuan province.

According to the forecast, droughts, flooding and rains will strike Xi'an in the next six months, said Zheng Jiangping, deputy director of the China Meteorological Administration's emergency response, disaster mitigation and public services department, at a news conference in Beijing on Thursday.

To better protect visitors, a weather monitoring system has been operating around the clock since April 1, Zheng said.

Every 30 minutes, about 215 weather stations will collect data on the conditions in Shanxi, Ningxia and Gansu. The information will then be analyzed to give observers an understanding of what dangers are present for the horticultural exposition in Xi'an, he said.

Another eight weather stations will be established inside the exposition and, every minute, will put out the latest data obtained from the monitoring, Zheng said.

The weather information will be released through the media, the website www.weather.com.cn and text messages.

This is the third time that a mainland city has been the site of the international horticultural exposition.

In 1999, Kunming, capital of Southwest China's Yunnan province, became the first place in the country where such an exposition occurred. Sixty-nine countries and 22 institutions took part in the event that year and more than 9.5 million visitors came to see the displays.

In 2006, Shenyang, in Northeast China's Liaoning province, was the site of the horticultural exposition. That event attracted 12 million visitors.

Wang Qian contributed to this story.