The Largest Act of Environmental Warfare in History
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Transcript of The Largest Act of Environmental Warfare in History
The Largest Act of Environmental Warfare in History
Steven I. DutchNatural and Applied Sciences
University of Wisconsin-Green BayGreen Bay, WI 54311-7001
Something New?
Topography of China
Loess in China
Huang He Diversions 400 BC - Present
Scale of Huang He Diversions
1890
1900
1910
1918
1932
1937
July, 1937
August, 1937
End of 1937
Japanese Strategy
1938
Extent of Flooding
(After Todd, 1949)
Military Effects of the Breach• Minor losses of Japanese troops and materiel• Few troops caught on the wrong side escaped• Chinese gain time for withdrawal and relocation of
capital• Flood also protects Japanese flank• Little additional fighting in Central China• Japanese capture of Wuhan (Hankow) delayed by
only a couple of months• No central authority in much of Central China• Communists gain support
Fatalities + Refugees, 1938 Flood
Fatalities, 1938 Flood
Refugee/Fatality Ratio, 1938 Flood
Flood Fatality Estimation
Flood Severity Warning Time Fatality Rate
High None 30 – 100 % (75%)
> 1 hour X Number still at risk
Medium None 3 – 35% (15%)
> 1 hour <1 – 6% (3%)
Low None 0 – 2 % (1%)
> 1 hour <<1 %
• Graham, W.J., 1999, DSO-99-06, A Procedure for Estimating Loss of Life Caused by Dam Failure
• Assuming poor understanding of risk downstream• Fatality rate in parentheses is recommended
prediction value
Casualty Model Applied to 1938
• Population of Henan, Anhui and Jiangsu flooded counties = 13.2 million (Lary, 2001)
• Medium severity, no warning (15%) 2 million fatalities
• Medium severity, > 1 hour warning (3%) 400,000 fatalities
• 844,000 fatalities = 6.4%
Visualizing the Risk
Lessons From Banqiao, 1975• > 1 m rain in 24 hours from typhoon• 1000 year dam but 2000 year floods• After nine days, a million people were still
stranded• 26,000 died in the flooding, 145,000 from
disease and famine• More violent event than 1938, but happened
in peacetime with intact infrastructure
Moral
Large at-risk population + Flat terrain + Lack of Mobility or Communications = Huge Death Toll
• Bangladesh 1971: 300,000• Bangladesh 1991: 140,000• Myanmar 2008: 200,000
What We’d Still Like to Know• Survivor Accounts: Need to Act Quickly• Exact chronology and extent of flooding• Effects of normal Huang He floods later• Specific Causes of Mortality– Drowning by flood?– Exposure of stranded victims?– Dehydration?– Water-borne disease?– Loss of Crops?