U.S. Floods of 1978
By C.A. Perry, B.N. Aldridge, and H.C. Ross of the USGS
The first significant flood of 1978 resulted from the February 6 and 7
"Blizzard of 1978." This storm formed in the Carolinas and moved
northward along the Atlantic seaboard. The storm produced record amounts
of snow and hurricane-force winds. Record tidal flooding occurred from
Boston, Massachusetts, northward to Portland, Maine. Total economic losses
from the storm, including damages directly caused by the storm and costs
of snow removal, approached $1 billion.
Spring floods accompanied melting of a large snowpack in the Red River
of the North Basin and the Missouri River Basin in the North-Central
States. Flooding in different areas continued through the spring months.
Above-average precipitation had produced a large, wet snowpack over much
of Minnesota, North Dakota, South Dakota, eastern Montana, and parts of
northern Nebraska and western Iowa. Much of the ground in the Missouri
River Basin froze earlier than normal during the winter season when the
ground had a high-moisture content, and the frozen ground would not absorb
the snowmelt. Consistently warm temperatures and rains on March 11-12
caused rapid snowmelt throughout the basin and flooding conditions within
a few days. A maximum discharge of record was recorded on the Wild Rice
River at Hendrum, Minnesota.
Flooding occurred in Wyoming and southern Montana as the result of
intense rains that began the evening of May 16 and continued through the
morning of May 19. Before the rain, the streams in the area were already
flowing at or near bankfull because of snowmelt and above-average
precipitation earlier in the spring. Fourteen streamflow-gaging stations
in Montana recorded discharges at or above the 100-year recurrence
interval, and about one-fifth of the 164 stations in Montana recorded
maximums of record due to this flood.
June and July were very wet months for Minnesota and Wisconsin. Storms
caused flash flooding on many different occasions throughout the 2 months
in both States. Flooding on July 1-3 was particularly severe in the
Kickapoo River Basin of southwestern Wisconsin. The flood caused
discharges that are the maximums of record at 11 gaging stations with
recurrence intervals of 100 years or greater. On July 5 and 6, Rochester,
Minnesota, received intense rains. The National Weather Service rain gage
at the airport recorded 4.99 in. of rain over a 3-hour period. The total
rainfall far exceeded the amount of a 100-year recurrence interval for
that time period. The floods caused by the storm were the largest of
record since 1888 on Bear and Silver Creeks and the largest of record on
the South Fork Zumbro River since 1855. At the headwaters of the Cedar
River, a record-setting flash flood occurred on July 16 and 17, which was
the second flash flood in 11 days.
On June 18, the U.S. Geological Survey made a measurement of an
extremely high discharge of 3,250 ft³/s for a 1.71-mi² drainage area in
the headwaters of a small tributary for Honey Creek in central Ohio. The
100-year recurrence-interval discharge for this site is slightly more than
1,000 ft³/s. Rainfall of 7 to 8 in. in 2 hours caused this significantly
large flood. This amount of rain is well above the 3 in. calculated for
the 2-hour, 100-year rainfall in the area.
Tropical Storm Amelia brought extremely intense rains to central Texas
on August 1-4. Rainfall of more than 48 in. in 72 hours occurred northwest
of the town of Medina. More than 30 of the 48 in. occurred on August 2,
setting a point rainfall record for the United States. In response to the
large rainfall, significant flooding occurred in the Medina River Basin.
The upstream reaches of the Guadalupe and Medina Rivers had the highest
floods recorded since records began for each station in 1848 and 1880,
respectively. Thirty-three deaths occurred, and the damage totals for the
area were estimated at $110 million.
Significant floods occurred from Michigan to Texas between September 11
and 14. Many areas had flash flooding as a result of storms moving through
the area. Some areas received as much as 10 in. of rainfall. The hardest
hit areas were central Arkansas and northern Louisiana, and Federal
disaster declarations were made for two counties in each area. Little
Rock, Arkansas, received 10 to 13 in. of rain the morning of September 13.
At several stations the 6-hour rainfall total was well above the 100-year
Two storms, the first from December 3 to 5 and the second from December
7 to 10, caused record flooding in Kentucky and West Virginia. Flooding
was most severe in the Licking, Kentucky, Salt, and Green River Basins,
and along the Ohio River. Maximum discharges of record were recorded at
many stations in the Tygarts Creek, Kentucky River, and Salt River Basins.
In West Virginia, discharges with recurrence intervals greater than 100
years were recorded in the Twelvepole Creek Basin. Total damages for the
flood were estimated to be greater than $100 million in Kentucky and $12
million in West Virginia.
The Southwest experienced recurrent flooding from November through the
end of the year as a result of a persistent series of upper-level
low-pressure systems that developed off the southwest coast of California.
These low-pressure systems caused frequent periods of widespread and
above-average precipitation in Arizona and New Mexico. Floods with
recurrence intervals greater than 50 years occurred in the Gila River