Typhoon Nida

Landfall | Summary
Posting Date: August 2, 2016, 10:00:00 AM

Typhoon Nida made landfall near the Da Peng Peninsula of China, about 32 km northeast of Hong Kong, at around 3:30 a.m. HKT on Tuesday, August 2 (19:30 UTC on Monday, August 1), before moving inland into Guangdong Province, China. Now downgraded to a tropical storm, it is expected to track deeper into southeastern China before dissipating on Wednesday.

Meteorological Summary

Typhoon Nida crossed over northern Cagayan in the northeast of Luzon, Philippines, as a tropical storm at 1:20 p.m. PHT (05:20 UTC) on Sunday, July 31, dumping 287 mm of rain before continuing northwestward to Hong Kong and mainland China, where it made landfall as a Category 1-equivalent storm. Wind gusts of up to 145 km/h were recorded near Hong Kong International Airport at landfall, and rainfall totals reached more than 100 mm for most of Hong Kong. China’s State Oceanic Administration (SOA) estimated that sea level off the Pearl River estuary could rise up to 2.2 meters.

Interaction with land has contributed to the rapid deterioration of Typhoon Nida as it has passed through Guangdong Province to Guangxi Province. Now a tropical storm, Nida is expected to continue weakening as it travels along its path west-northwestward, moving further inland and bringing additional rain to the Pearl River Delta of southeastern China before dissipating on Wednesday.

Track map of Typhoon Nida. (Source: JMA)

Nowhere else in the world are typhoons more frequent than in the Northwest Pacific basin due to its large expanse of very warm water, which fuels storm formation. On average, about 29 tropical cyclones are spawned in this basin each year, 20 of which reach typhoon status. Comparatively, the North Atlantic basin generates around 11 tropical cyclones in an average year, six of which turn into hurricanes.

Nida is the first typhoon to track within 120 km of Hong Kong since Typhoon Usagi, which made landfall 130 km to the east-northeast of the city on September 22, 2013. Usagi affected multiple locales, including Victoria Harbour, Hong Kong International Airport, Lau Fau Shan, and Tai Mei Tuk, and prompted a Level 8 Tropical Cyclone Signal from the Hong Kong Observatory.

Because of Hong Kong's small size, landfalls are relatively rare, occurring every two or three years; however, storms pass close enough to cause loss annually. Hong Kong is sheltered by coastal mountains, which reduce wind risk from typhoons. The highest inland flood risk is along the coastal mountains due to orographic lifting. Due to its extreme western location and its expansive coastline, China experiences more tropical cyclone landfalls than any of its neighboring countries, with the southeastern coast most at risk. The rivers in the region elevate rain-induced flood risk from weak typhoons.

Reported Impacts

No major damage has been reported. A Level 8 Tropical Cyclone Signal—warning of gale- or storm-force winds blowing at sea level at sustained speeds as high as 117 km/h with gusts of up to 180 km/h—was issued by the Hong Kong Observatory on Monday night, China's National Meteorological Center issued a red alert warning for gales and torrential rain in its southern provinces, and the SOA issued a red alert for ocean waves and storm tides of up to 11 meters off the coast of Guangdong Province. Guangzhou, the capital of Guangdong, launched a first-class-level emergency response order on Monday—a first for the city—which suspended work, production, and classes in the area and mandated that all people outside of rescue personnel stay indoors. Hundreds of flights in and out of Hong Kong, Guangzhou, Shenzhen, and Zhuhai were canceled, and China officials suspended high-speed train and bus service in the region. All passenger ships, tourist boats, and ferry services at Guangzhou Port were also suspended.

In China, flash floods have been known to occur along areas of poor drainage and along rivers and tributaries, often far inland and days after storms have made landfall. Rain-induced flooding can also trigger mudslides, both of which may exacerbate already poor conditions in China, where floods caused large amounts of damage earlier this summer.

Exposure at Risk

Typhoon activity poses a risk of damage to nearly all of Southeast Asia, especially in heavily populated areas. Hong Kong is currently home to more than 7 million people. When compared to other coastal areas in the South China Sea, Hong Kong’s mountainous coastline and strongly enforced building codes lessen wind vulnerability. Its heavy investment in a flood defense system keeps inland flood risk within the city relatively low, although flooding is common in the surrounding areas and particularly in the mountainous regions. The reclamation of land is increasing storm surge vulnerability in the region due to exposure proximity to sea level and the narrowing of Victoria Harbour.

Most of the single-family houses in Hong Kong are made of reinforced masonry or concrete. Condominiums, commercial, and industrial buildings—often mid- or high-rise structures—are mainly made of reinforced concrete or steel, reducing wind vulnerability. However, many high-rise buildings have basements where service equipment is located; this kind of equipment is expensive and vulnerable to water.

A pocket of concentrated industrial exposures is located in Guangdong Province near Guangzhou—the economic center of the Pearl River Delta located at the heart of one of mainland China's leading commercial and manufacturing regions. To the south in Hainan Province, several resort areas have relatively high exposure.

The majority of residential buildings in China are masonry, with unreinforced masonry still found in older buildings, particularly in rural areas. In contrast, urban apartment buildings tend to be mid- or high-rise structures, many of which have commercial establishments on the ground floor; mid-rise buildings are often confined masonry while high-rises tend to be reinforced concrete. Commercial and industrial structures still vary widely across China, ranging from poorly constructed low-rise masonry structures to well-maintained mid- and high-rise reinforced concrete buildings constructed to strict code standards. Generally, commercial and industrial buildings are more resistant to wind and water damage than residential buildings.

Industry Impacts

Insurance take-up rates in Hong Kong are high for both residential and commercial buildings, whereas take-up rates for building contents are higher for commercial and lower for residential lines. Weak-wind typhoons that impact vast areas and generate significant rainfall have often contributed more to insured typhoon losses in China than landfalling storms with high winds. Residential take-up rates in China are low, while commercial take-up rates vary by province; in Guangdong, commercial take-up rates are about half with a combined deductible for buildings and contents.

While the full impacts of Nida have yet to be assessed, the lack of major damage reports suggests that insured losses are likely to be low.

Landfall | Downloads
Posting Date: August 2, 2016, 10:00:00 AM