Forensic Engineering - The Ripple Effect: The Fate of Freshwater in the Twenty-First Century - page 188

Humphreys and Abbot developed the theory that “levees only” could control flood-
ing along the lower Mississippi. They believed that dams, reservoirs, and cutoff canals
were no longer necessary. The levees-only policy profoundly influenced everything the
Corps did on waterways across the country up through the Second World War.
In 1879, Congress established the Mississippi River Commission, a panel of experts
who oversaw the construction of dozens of miles of levees along the river, the dredging
of its shallows, and the building of “mattresses” made of woven willow branches, to pre-
vent erosion of riverbanks and to improve navigation and flood control.
But flooding persisted. In 1882, one of the most devastating floods on record des-
troyed the delta region. Major flooding hit again in 1912 and 1913, when two terrifying
floods overwhelmed levees and devastated the lower Mississippi Valley. In 1916, the re-
gion was swamped yet again. Still, the Corps and the Mississippi River Commission
continued to rely on levees as their primary defense.
In the fall of 1926, heavy rains swept across the Midwest, and by the following spring
a large region, stretching from Minnesota to Missouri, was soaked. In the spring, heavy
snowmelt and persistent rains set the stage for the Great Mississippi Flood of 1927 , one
of the worst disasters in American history. In late March, rivers across Kansas and Iowa
swelled over their banks as tons of water rushed downstream. By mid-April, the flood
crest had worked downstream to Mississippi and Arkansas, and the Big Muddy rose to
unprecedented heights. The Mississippi spread a mile wide, a hundred feet deep, and
flowed downstream at a fast nine miles per hour. On Good Friday, April 15, the Mis-
sissippi was flooded along most of its 2,320-mile course and in some places had spread
eighty miles wide, according to a report by the Goddard Space Center. On April 22,
levees near Greenville, Mississippi, broke; a tremendous gush of water flowed inland
through the breach—at a rate twice the flow of Niagara Falls, by one estimate—and the
city was sunk under ten feet of water.
Along the riverbank, levees broke in 145 places, flooding twenty-six thousand square
miles in nine states—Arkansas, Illinois, Kentucky, Louisiana, Mississippi, Missouri,
Tennessee, Texas, and Oklahoma—up to a depth of thirty feet in places. In portions
of the lower Mississippi Basin, water remained above flood stage for two months. The
Flood of 1927 destroyed cities, towns, and farms, killed 246 people, and led to the dislo-
cation of nearly 700,000 more. Many of the refugees were African Americans, who were
moved to 154 temporary camps and conscripted, sometimes at gunpoint, to shore up
levees and excavate piles of silt deposited by the flood.
Until Hurricane Katrina hit New Orleans in August 2005, the Great Mississippi
Flood of 1927 was the nation's worst natural disaster. One of its lessons was that levees
alone are insufficient for flood control.