The menace of gathering storms gaining momentum
Research data published by meteorologists and geographers reveal that the entire region is not well prepared for the torrential downpours now accompanying severe storms that have grown notably more ferocious in recent years under global warming. People living in the region are more likely to be caught off guard with the sudden onset of extreme weather.
Last year, the Swiss Reinsurance Company rated the Pearl River Delta (PRD) region as the world’s third most vulnerable urban area to river floods, coastal storm surges and severe weather. Only the Tokyo-Yokohama metropolitan area and Metro Manila are considered more vulnerable than the PRD.
Researchers acknowledged that the likelihood of a severe natural disaster in this area may be remote, but that just one massive storm could have catastrophic results, affecting one of China’s most important commercial and manufacturing centers, an area that is home to more than 42 million people.
The potential magnitude of any such catastrophe here may be gauged from the disaster that struck the New England States, including New York City, in late October 2012. Tropical storm Sandy, downgraded from a hurricane when it made landfall, killed 117 people, 48 in New York City. Power to 7.9 million businesses and households in 15 states was cut.
The tempest struck within two kilometers of Wall Street, forcing closure of the New York Stock Exchange for two consecutive days for the first time since 1888. Damage in the states of New York and New Jersey, the hardest hit areas, came to nearly $80 billion.
All coastal megacities in Southeast Asia are exposed to cyclones similar to Sandy, the second most destructive tropical cyclone on record, said Faith Chan Ka-shun, assistant professor at the University of Nottingham’s Ningbo campus.
Meteorologists and geographers have described Hong Kong as “lucky” so far. Most powerful cyclones that have wrought heavy losses to lives and property in recent years have missed the city, some veering off at the last minute to make landfall in nearby regions.
Martin Williams, a Hong Kongbased writer specializing in conservation and the environment, cited Typhoon Usagi in a recent article. The storm that struck last September forced Hong Kong to raise the No 8 storm signal, but killed 35 people on the mainland.
Williams pointed to super typhoon Haiyan, which struck the Philippines last November, leaving 6,340 known dead and more than 1,000 missing. Their bodies have never been found. He described it as similar to the deadly typhoon that hit Hong Kong in 1906 — the unnamed storm struck suddenly, killing 15,000 people in the city.
Another dreadful storm surge happened in 1937 in Hong Kong, taking 11,000 lives.
Chan cited Typhoon Wanda in 1962, which generated a severe storm surge, “at a one-in-50 return period scale”, with a recorded mean sea level (MSL) of 5.34 meters that caused a 1.4-meter surge in Victoria Harbour, causing seawater to overflow the embankment and inundated North Point and Sheung Wan among other districts on Hong Kong Island. Wanda killed 130 people and destroyed 72,000 properties, with economic losses estimated at HK$4.9 million.
Experts highlighted the flooding and storm history in the region not only because such deadly extreme weather is likely to recur, but also that the intervals between episodes of extreme weather are shorter. Floods cannot easily be forecast, but it is well known and the risks are growing.
New York City’s storm warning system, for example, was activated less than 48 hours before Sandy struck. Preparation time before the onset of a deadly storm is becoming increasingly important.
H Y Mok, a senior scientific officer with the Hong Kong Observatory (HKO), said that in the event of a serious natural disaster in Hong Kong, a large-scale evacuation would be difficult in densely populated districts.
Lam Chiu-ying, adjunct professor at the Department of Geography and Resource Management, the Chinese University of Hong Kong, as well as former HKO director, told China Daily that to obtain a clear assessment, one should examine flood risks arising from a storm surge, and historical records showing that the mean sea level around Hong Kong is progressively rising. Equally important is the increasing frequency of extreme weather, which many experts believe is linked to climate change.
The UK’s National Weather Service says a storm surge arises from a combination of low air pressure, high winds and favorable tidal conditions that may lead to extensive flooding inland, posing extreme danger to people living in coastal areas.
Hong Kong is hit by six typhoons every year on average. The HKO keeps a database of the storm surge from every one of them. It’s been a long time since the city was hit by a severe storm surge, but as Chan noted, climate change will lead to increasing peak wind intensities, and rising frequency and intensity of storm surges.
The HKO and the Macau Maritime Administration predicted the rise of the sea level some years ago. They predicted an annual rise of 3.9 millimeters in the PRD estuary. That would result in a 20-centimeter increase in the sea level by 2050. Last year, the HKO updated its projections and estimated that the sea level will rise by 40 centimeters, on average, by the middle of the century.
There are other factors, however, that threaten to make rising sea levels even more of a threat. In May, it was reported by NASA that six unstable and rapidly melting glaciers in the Antarctica could release enough water to raise the sea level by roughly 1.2 meters over the next 200 to 1,000 years. NASA researchers described the glaciers’ retreat as having “reached the point of no return”.
The situation has aroused concern among meteorologists worldwide. They quickly pointed to the fact that rising sea levels, underpinned by increasingly extreme weather, raise the risk of flooding inland. In Hong Kong, the consequences of any such major event are difficult to map out.
The HKO’s Mok told China Daily that because Hong Kong has a complex coastline and mountainous topography, it would be technically difficult and costly to prepare an inundation map that would allow meteorologists to predict storm surge potential in the city and help with developing contingency plans.
Inundation is common in the PRD. Hong Kong boasts a better drainage system. Chan said the Drainage Services Department (DSD) “has done what it can” to sort out flood issues with engineering approaches. Nonetheless, he warned that “the intensive rainfall could still be too serious to cope with, or sometimes the blockage of storm sewers becomes unavoidable, particularly in some highly urbanized districts”.
“As the urbanization rate is proceeding unbelievably fast, drainage capacities and flood measures may not be equally equipped to meet adequate standards to protect urban, populous areas, which are the common problems in all PRD cities and most of the Chinese megacities, in my opinion,” Chan said. Timothy Chui contributed to the article.