Typhoon Nina
Typhoon Nina was a powerful typhoon that originated as a tropical depression in the Philippine Sea on July 30, 1975. It intensified rapidly due to warm ocean waters, achieving peak wind speeds of 155 miles per hour by August 2. The storm made landfall in Taiwan on August 4, causing severe damage and fatalities from flooding, landslides, and power outages. After crossing Taiwan, Nina weakened slightly but regained strength before making landfall in China on August 5. The storm unleashed unprecedented rainfall, drastically increasing precipitation from expected levels, which led to catastrophic dam failures, notably at the Shimantan and Banqiao dams. These failures released massive amounts of water, resulting in devastating floods that inundated vast areas and claimed an estimated 171,000 lives, with some estimates suggesting the total could be as high as 229,000 due to subsequent famine and disease. The aftermath of Typhoon Nina highlighted significant flaws in dam management and infrastructure in the region, prompting improvements in construction and disaster response measures in subsequent years. Despite advancements, experts warn that a similar storm could still have severe impacts today due to ongoing vulnerabilities in the area.
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Typhoon Nina
Date: July 30–August 6, 1975
Place: China; Taiwan
Result: 171,000 people killed; $1.2 billion in damage
Overview
The storm that became Typhoon Nina began as a tropical depression in the Philippine Sea on July 30, 1975. The warm seawaters and winds allowed it to develop quickly into a typhoon. Typhoon Nina crossed Taiwan with devastating winds and heavy rain before moving toward China. There, although weakened, the storm dumped huge amounts of rain on the countryside, overwhelming waterways and causing many dams to fail. Most of the 171,000 people who died because of Typhoon Nina died because of the sudden gushes of water unleashed when the Banqiao and Shimantan dams failed.
Origins. Typhoons (as well as cyclones and hurricanes—all three refer to the same type of storm) develop when the winds in thunderstorms over warm tropical seas draw additional moisture into the air. The moisture is converted to heat, which causes condensation. The resulting cycle of water being pulled up and released creates a circular flow that increases the storm's energy and winds. The moisture drawn up from the tropical waters eventually pours out of the storm as rain. Once the winds reach thirty-nine miles per hour, it is considered a tropical storm. Nina reached this stage on July 31.While over the water, the storm built rapidly in intensity, reaching peak wind speeds of 155 miles per hour on August 2.
Taiwan. The storm made landfall on the eastern coast of Taiwan on August 4 with up to 150 mile per hour winds. The first tropical storm to hit Taiwan in 1975, Nina battered the country with heavy rains that caused flooding, destroyed roads, damaged houses, knocked out power, started landslides, and shut down public transportation. Five people were killed and eighteen seriously injured before the storm moved toward the Formosa Strait and crossed over to China.
China. The path Typhoon Nina took across Taiwan went over the island's central mountain range. This weakened the storm considerably, dropping wind speeds to only about 30 miles per hour. The winds kicked back up to around 110 miles per hour before the storm made landfall in China on August 5, then dropped again as the storm continued inland. As Typhoon Nina crossed the country, it collided with a cold front that dramatically increased the precipitation dropped by the storm from the expected 12 inches to nearly 42 inches. The nearly three and a half feet of rain that fell in that one day was roughly equal to the amount of rain the area usually receives in an entire year. The rain fell so hard that witnesses reported that birds were killed by its sheer force.
The intense rainfall caused much of the same kind of damage experienced in Taiwan, as the ground was inundated with huge amounts of water. The worst was yet to come, however. The sudden influx of water filled the dams and waterways across the affected area, but dam operators were originally told not to open the spillways in an effort to avoid increasing the flooding caused by the overflow of smaller streams and bodies of water. When the storm took out phone and power lines, there was no way for dam operators to receive authorization to open the spillways and release pressure on the dams.
The Shimantan dam on the Hong River failed first, at about 12:30 a.m. on August 8. In less than five hours, it poured the entire contents of its 120 million cubic meter reservoir, or about 32 billion gallons of water, out onto the countryside. About half an hour later, the Banqiao dam on the Ru River also failed, setting loose a torrent of water traveling more than 30 miles per hour toward unsuspecting villages. The sudden gush of water caused more than sixty smaller dams to fail, increasing the wave of water that poured down on towns where thousands were sleeping. The resulting flood covered more than 25 million acres and claimed the lives of an estimated 85,000 people. Many of those who survived were marooned for days on roofs or small areas of higher ground without food or clean water.
Impact
The days after the flood were extremely difficult for many of those who survived the deluge. With so much water suddenly released from so many dams, the water took a very long time to recede. This, coupled with damage to roads caused by the gushing waters, made it difficult or impossible for rescuers to reach some areas. Many people were trapped amid the dirty water and reduced to eating dead animals that floated by or food that was air-dropped into the water, and disease became rampant. In the aftermath of the flood, thousands died from hunger, disease, or exposure to the summer heat. While most reports list the number killed by Typhoon Nina at 171,000, the deaths that occurred afterward were not always attributed to the storm. Some estimates place the overall loss of life from the typhoon at about 229,000.
Although both technology and China's capability to respond to such a storm have improved in the years since, the areas that were most seriously affected by the 1975 Typhoon Nina flooding remain remote and hard to reach. Experts believe that even in the twenty-first century, a similar storm would still devastate the area.
Experts also note that the way dams were built in the area, with many small dams operated by different companies along a single stretch of river, increased the damage in 1975. The small dams could not withstand the huge amounts of water, and the fact that they were run by different companies hampered communication. Experts have pointed out that new chemical companies that have since been built along some of these rivers would also worsen conditions should another catastrophic storm strike.
However, experts say that new dams are generally built to withstand the worst conditions that can be expected, and that the 1975 flooding that followed Typhoon Nina set that bar very high. Technology has also improved, and the new dams are built with concrete, not the clay that made up most of the dams that failed during Typhoon Nina.
Bibliography
"The Catastrophic Dam Failures in China in August 1975." San Jose State University Department of Economics. San Jose State University. Web. 19 May 2016.
Cockburn, Carrie. "Explainer: How Are Typhoons Formed?" Globe and Mail. The Globe and Mail, Inc., 11 Nov. 2013. Web. 19 May 2016.
Demetriou, Danielle. "The World's Deadliest Typhoons." Telegraph. Telegraph Media Group Limited, 21 Sept. 2011. Web. 19 May 2016.
Fish, Eric. "The Forgotten Legacy of the Banqiao Dam Collapse." International Rivers. International Rivers, 8 Feb. 2013. Web. 19 May 2016.
Gronstal, Aaron. "Storms in the Machine." Goddard Institute for Space Studies. National Aeronautics and Space Administration, Nov. 2012. Web. 19 May 2016.
"Typhoon Nina Batters Taiwan with Rain, Wind." Sarasota Herald-Tribune. Gateway Media, Inc., 4 Aug. 1975. Web. 19 May 2016.