Great River Basin Floods

For destructive power, no stream matches China's Yellow (Huang) River. Known as "the Ungovernable" and "China's Sorrow," it flows 4,631 kilometers to the sea.

Legend sets one of its first floods twenty-three centuries before the birth of Christ. A monstrous flood was reputed to have lasted for thirteen years. What is indisputable is that Chinese dynasties have attempted to control floods on the river by both building dikes along the banks and dredging to deepen the channel and keep it clear of obstructions.

The Han dynasty built a unified system of dikes between 202 and 220 CE. This was the first attempt to unify all the various dike systems that had previously been built by farmers and villagers. Repeated attempts to ensure flood protection over the succeeding years proved futile. Calamitous floods occurred nearly every other year.

The river's periodic changes of course—twenty-six significant ones in the last thirty-five hundred years—further challenged flood protection works, In 1855 the river overwhelmed a dike near Tungwa Hsiang, about 48 kilometers east of Kaifeng. Engineers tried to repair the dike system over the next six years but failed. Uncontrolled, the river rampaged over the countryside, finally settling into its present channel about 804 kilometers to the north of where its main channel had been nearly six hundred years before.

In 1887 heavy rains in Hunan Province brought about what still ranks as the worst flood disaster in human history. The Yellow River tore through the dikes at Cheng-chou and within minutes completely inundated the city. Racing toward the east, the river demolished six hundred villages; another fifteen hundred villages in the flood-plain experienced severe flooding.

The river deposited so much sediment that it prevented any agricultural production. The exact number of dead will never be known, but the estimate ranges from 2 million to 4 million. Significant breaches appeared again in 1921 and 1929. A flood in 1939 destroyed crops and villages. Japanese occupation prevented the distribution of relief supplies. About 10 million persons were left home-less, and about two hundred thousand died in the ensuing famine.

Floods along China's other principal river, the Yangtze (Chang), also have caused much suffering. The Yangtze is the longest in the country at 5,471 kilometers. Nearly 18,129 square kilometers of lakes are connected to the Yangtze system, providing space for upstream floods. However, if heavy precipitation falls on downstream areas already swollen with flood-waters, disaster may result.

The river's formidable discharge into the sea can double. If dikes cannot contain the floods, the water spills over into an area that may reach 181,299 square kilometers along the middle and lower reaches of the river. In 1931 weeks of constant rain led to the Yangtze cresting 29 meters above its normal stage.

More than 3.7 million Chinese died, mainly from famine, and property losses reached $1.4 billion, an incredible amount for that time. Again in 1998 severe floods on the Yangtze displaced millions of people and killed more than three thousand. In all, the floods may have affected as many as 250 million people—millions directly and other millions because of health problems or the disruption of vital electrical, transportation, and water distribution systems.

In North America the Mississippi River basin gathers water from thirty-one states and two Canadian provinces. It drains 41 percent of the continental United States, excluding Alaska, From its headwaters in Minnesota to the Gulf of Mexico, the Mississippi River flows 3,778 kilometers. To this must be added the 4,092-kilometer-long Missouri River, the longest in North America, which empties into the Mississippi just north of St. Louis; the Ohio River, which joins the Mississippi at Cairo, Illinois, and actually contributes more water to the Mississippi than the Missouri does; and a number of lesser tributaries.

The combined water from these rivers flows southward to the Gulf of Mexico, like water going into a funnel. Spanish explorer Hernando de Soto saw a flood on the Mississippi in 1543, perhaps the first European to do so. Since that time floods have periodically returned. Congress in 1879 established the Mississippi River Commission, a mix of civilian arid military personnel to develop plans to improve flood protection and navigation along the Mississippi.

The commission mainly relied on levees, a method advocated by the U.S. Army Corps of Engineers. Local levee districts followed suit, and levee construction or improvement marked much of the lower stretch of the river (beneath Cairo, Illinois). The work could not be completed fast enough. Floods occurred every year from 1881 to 1884, again in 1886, and a major one in 1890. More flood devastation came in the early twentieth century.

Finally, the 1927 flood compelled a reevaluation of flood control methods. Close to five hundred people perished, over 6.4 million hectares of land were flooded, forty-one thousand buildings were destroyed, 162,000 homes were demolished, 325,000 people were cared for in temporary Red Cross camps, and another 311,000 people were temporarily put up in private homes.

The flood—actually a sequence of floods beginning in January and lasting through May—clearly showed that reliance on levees was not the answer. Rather, in 1928 Congress authorized a new Corps of Engineers plan that combined bigger and stronger levees with various human-made outlets, dredging, banks, and other measures.

Of course, construction did not stop the floods nor the damage. Indeed, seventeen major floods have hit the lower Mississippi River since 1879, an average of one major flood every seven years. A particularly devastating flood struck the Ohio and Mississippi Rivers in 1937. A flood in 1973 killed twenty-seven people, inundated 4.5 million hectares, and caused $420 million in damage, it almost took out the Old River Control Structure, which regulates the amount of water that flows into Louisiana's Atchafalaya Basin, a major safety valve for floodwaters. Had the structure gone, eventually the Mississippi River would have changed course and stranded Baton Rouge and New Orleans miles from the river's main channel.

The economic and public health problems would have been incalculable. The structure held, however, and the Corps of Engineers estimated that flood control measures prevented $7 billion in damages. As for the middle and upper stretches of the river, a 1993 flood that resulted from exceptionally long and heavy rainfalls inundated 2.6 million hectares, left from $12 billion to $16 billion in damages, and caused at least thirty-eight deaths. On the other hand, the Corps of Engineers estimated that flood works—principally levees—prevented more than $19 billion in flood damages.