Shanghai's flood prevention authority issued a flood alert over the weekend as water levels on the Huangpu River exceeded warning levels.
Typhoon Malakas and astronomical tides were to blame, authorities said yesterday.
Weather forecasters issued an orange alert for waves and a yellow alert for storms as Malakas moved along the east coast of the Chinese mainland, Xinhua news agency reported.
China's National Marine Environmental Forecasting Center said Malakas was off the southeast coast of Zhejiang Province at 8am yesterday.
It is expected to bring waves of up to nine meters high in the East China Sea. Waves up to four meters are expected near the Diaoyu Islands, in the Yellow Sea, Taiwan Strait, and off the coast of Shanghai and Jiangsu, Zhejiang and Fujian provinces. Storm surges of up to 100 centimeters are expected in coastal areas in Jiangsu and Fujian.
According to the Shanghai Flood Risk Information Center, water levels at the Wusongkou, Suzhouhe and Mishidu sections of the Huangpu all exceeded warning levels yesterday morning.
The rising water forced local authorities to launch emergency response measures and shut tidal gates.
Gates on the flood prevention dams have been closed along the Huangpu and Suzhou Creek after the water level beneath the Waibaidu Bridge, where the river meets the creek, reached 4.88 meters — 33 centimeters above the warning level — yesterday morning, said Zhang Zhenyu, deputy director of Shanghai Flood Control Headquarters.
"The high water level is expected to last till Monday night to pose great threats to the city's flood prevention walls," Zhang said. Some ferry services over the Huangpu might also be suspended, he added.
The headquarters issued a blue alert, the lowest of the alert system, but warned about high flood risk because the typhoon coincides with the eighth major tide in Shanghai this year.
Flood prevention officials would patrol and inspect flood dams round the clock to ensure safety, Zhang said.
Fishing boats in the East China Sea have been ordered to stop fishing and berth at harbors, while those working close to the shore have been evacuated.
The typhoon would bring strong winds and showers to the city with the impact lasting till tonight, Shanghai Meteorological Bureau said.
Strong winds of about 40 kilometers per hour are forecast to sweep through the city's inland areas tonight, while areas at the mouth of Yangtze will face gales of about 80 kilometers per hour.
Showers hit the east part of the Pudong New Area yesterday as well as the outskirts of Fengxian, Jinshan and Chongming districts.
Temperatures will be between 23 and 27 degrees Celsius today with showers and cloudy weather. It should be a bit cooler tomorrow with the temperature dropping to 21 degrees. A new round of rainfall would arrive on Wednesday in the wake of the typhoon, the forecaster said.
Malakas, this year's 16th typhoon, was observed 510 kilometers off Shanghai's east coast at 11am yesterday, according to the weather bureau.
The typhoon has improved the city's air quality. The Air Quality Index was about 50, or excellent, across the city yesterday and will remain so today, said the environmental monitoring center.
