Typhoon Haikui

Landfall | Summary
Posting Date: August 8, 2012, 12:45:00 PM

Typhoon Haikui, the 11th typhoon of 2012 Pacific season, made landfall in Hepu Township in Xiangshan County of China’s Zhejiang Province at 3:20 am local time this morning (Wednesday, August 8). Maximum sustained winds at landfall were 138 km/h, making it a Category 1 storm. It is delivering substantial rain. According to the head of the Zhejiang provincial meteorological bureau, the storm is expected to have been in Zhejiang province for 24 hours by the time it exits to neighboring Anhui Province, to the northwest, later tonight (local time). The storm has weakened considerably since landfall, and is now at tropical storm strength. As of the Japan Meteorological Agency's (JMA) 12:45 UTC advisory today, August 8, it is located in Lin'an County in Northwestern Zhejiang province, moving 18 km/h in a west- northwest direction, with maximum 1-min sustained wind speeds of 82 km/h. Despite its weakened state, Haikui remains a large storm with a radius of tropical storm-force winds around 390 km. Current Conditions Typhoon Haikui has delivered heavy downpours throughout Zhejiang Province today, washing out roads and prompting local railway authorities to cancel all passenger trains to and from Hangzhou—the capital and largest city of Zhejiang—and Ningbo—a seaport city in the province’s northeast. In the city of Lin'an, in Hangzhou, flooding stranded about 130 people in three hotels; their rescue has been made difficult because the roads accessing these hotels are flooded. Meanwhile, in Anji County, also in Zhejiang Province, Typhoon Haikui’s heavy rains destroyed a bridge in a scenic tourist area, leaving another 300 people stranded. According to the provincial power company, rains from Haikui have caused 12 townships in Zhejiang to lose power. In addition to the rain, strong winds from Haikui have caused some disruptions as well, notably the closure of Hangzhou Xiaoshan International Airport at 7:30 am local time this morning. About 225 kilometers north of Haiku’s landfall location, the bustling city of Shanghai (population 23 million) experienced heavy flooding; rain from Haikui fell on the city for nearly 17 hours beginning at 8 pm local time yesterday (August 7). As much as 58 millimeters of rain fell in the city’s commercial center in one hour today, August 8, according to the Shanghai Public Weather Service. Some areas of Shanghai received rainfall amounts totaling nearly 130 mm. City authorities limited public transit, including canceling more than 500 flights and stopping at least 600 trains; sections of the Shanghai subway system have also been suspended as a result of the storm. Throughout the city, all construction sites and parks have been closed. In advance of the storm’s arrival, all outdoor group activities were banned and more than 370,000 people were relocated. In Zhejiang Province, meanwhile, the evacuation tally was more than 1.5 million. To the north of Shanghai, in southern parts of China’s Jiangsu Province, Haikui is expected to bring rain and strong gales today as it tracks west-northwest. As of 11 am local time this morning, authorities in Jiangsu Province had ordered more than 170,000 people to evacuate and more than 18,000 ships to return to harbor. The typhoon’s arrival in China prompted a red alert warning—the highest alert in the country’s four-tier warning system. A red alert from the China Meteorological Administration indicates winds of 118 kilometers an hour or more. Flood Hazard The weakened winds and slow-moving nature of Haikui after landfall made flooding the predominant threat. Some isolated areas have received over 200 millimeters, and another 150 to 250 millimeters are expected to fall as Haikui continues inland, with some isolated locations receiving even greater amounts of precipitation. Since the late 1940s, China has continued to strengthen flood control measures. To that end, more than 280,000 km of embankments, 86,000 reservoirs, and 97 key flood retention areas have been completed to protect the country against future flood losses. Thus, flood risk in China depends on both the accumulated runoff (which is a function of precipitation level, topography, and soil conditions) and flood defenses, which vary by region. Exposure at Risk Zhejiang Province is home to more than 9 million people. Historically, adobe and brick with wood-frame have been the predominant construction types for single-family homes in China, and they are still widespread in rural areas. These are usually poorly engineered structures and generally not insured. Insured single-family homes are predominately confined masonry and reinforced concrete. Concrete is less vulnerable to flood loads, and also to lateral wind loads. The vulnerability of buildings to flood damage also varies by construction type. For a given flood depth, a residential wood-frame building is expected to sustain more damage than a residential masonry building. Concrete construction is less vulnerable to flood than steel (which may experience surface corrosion and rust-induced expansion) or masonry structures (whose weak connections between building elements makes it permeable to water). Concrete buildings have a strong frame structure, but may suffer from cracking and rebar expansion. Commercial buildings, including those in the bustling hub of Shanghai, usually have stronger foundations than residential buildings, and are thus better able to resist flood loads. Forecast Track and Intensity The storm’s winds have been weakening over land and are expected to continue to do so. However, Haikui will continue to deliver large amounts of rain, raising the risk of landslides and flooding in inland locations along the storm’s projected trajectory. Haikui is expected to maintain its present movement (west-northwest) as it tracks from northwestern Zhejiang Province into Anhui Province. A cold frontal system to the north is not strong enough to redirect Haikui towards Shanghai as was earlier thought. Because of the storm’s large size, the duration of heavy rain will likely be more than 24 hours by the time it leaves Zheijiang Province late tonight (local time). Typhoon Haikui’s path is similar to that of another storm that wreaked havoc a few years ago in nearly the same region. In August 2004, Typhoon Rananim made landfall just south of where Haikui made landfall, and brought high winds and heavy rain to Wenzhou. Maximum one-minute sustained winds as high as 160 km/h—substantially higher than Haikui’s—were observed. Rananim had a narrow precipitation shield, but heavy precipitation rates near landfall caused nearly 400 mm to fall in Linhai, in central Zhejiang province. Rananim was the strongest typhoon in the area since Winnie (1997), and caused at least 100 deaths, damaged or destroyed over 130,000 homes and left 270,000 hectacres of farmland in ruins. If Rananim were to recur today, AIR estimates insurable losses would be approximately RMB 6 billion, while insured losses would be around RMB 1 billion. The AIR tropical cyclone team is monitoring Tropical Storm Haikui closely and will provide updates as warranted by events.

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Posting Date: August 8, 2012, 12:45:00 PM