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?