U.S. Floods of 1979

By C.A. Perry, B.N. Aldridge, and H.C. Ross of the USGS

On February 20, 1979, a record-breaking storm hit the Island of Hawaii and inundated the island with torrential rains for the following 72 hours. Twenty-three inches of rains fell at the Hilo Airport in 24 hours. This surpasses the previous record rainfall in 24 hours by more than 5 in. Record 48- and 72-hour rainfalls also were recorded. The resulting floods ranged in magnitude from discharges having recurrence intervals of 10 to 100 years. Runoff from the rains caused roads to be closed for several hours, caused flooded basements, and eventually ponded in low-lying areas. Streams in and around Hilo had near-record flows.

Spring flooding was severe in parts of Illinois and Missouri. Nearly every stream in Illinois was above flood stage during March. Flooding was especially severe along the Rock and Kankakee Rivers. The high tributary inflow caused the Mississippi River to be 7 to 12 ft above flood stage, but the river was easily contained within the levees except in areas where major rivers, such as the Illinois and Missouri, flow into the Mississippi.

The worst flooding since 1969 struck Minnesota late in March. Rapid snowmelt caused flooding in the Red River of the North Basin.

Several floods occurred in the southeastern United States from March to May. The worst of these floods was caused by the rainfall on March 3-4 and April 11-14. On March 3-4, 10 to 14 in. of rain fell near Pensacola, Florida, as much as 12 in. fell in eastern Mississippi, and 8 in. fell in western Alabama. Maximum discharges of record and discharges with recurrence intervals of 100 years occurred in parts of the Tallapoosa River Basin of Georgia and Alabama. Rains on April 11-13 caused severe flooding in Mississippi, Alabama, and the northwest corner of Georgia. Floods reaching 50- to 100-year recurrence intervals were recorded in the downstream reaches of the Coosa and Tallapoosa Rivers in Alabama. Several tributaries in the middle of the Tombigbee River Basin and the lower half of the Black Warrior River Basin, both in Alabama, had the highest discharges in 80 to 100 years. On most streams in the northern and eastern part of the Pearl River Basin in Mississippi discharges were greater than the 100-year recurrence interval. Damages from these floods in Mississippi, Alabama, and Georgia totalled $386 million. Floods also hit the Austin-San Antonio and Houston-Galveston areas of Texas in April. These were the worst floods, in terms of water levels, number of people affected, and dollar damages, to occur in the Houston area.

Tropical Storm Claudette caused severe flooding from Texas to Indiana after it made landfall in Louisiana on July 24. The storm caused torrential rains in 12 counties in the extreme southern corner of eastern Texas that includes the Houston and Galveston areas. Rainfall was 20 to 40 in. over the area. Floods occurred on many small creeks and bayous between and within the San Bernard and Trinity River Basins. Southern Indiana was also hit by remnants of Tropical Storm Claudette, which produced as much as 10 in. of rain in some areas. Severe floods resulted, especially in south-central Indiana.

Three hurricanes affected the United States during late August and early September. Hurricanes David, Elena, and Frederic hit the Southeastern States, and David and Frederic also hit Puerto Rico. None of the hurricanes caused significant flooding in the continental United States. However, intense thunderstorms associated with the hurricanes caused flash flooding and coastal storm surges. Puerto Rico had significant floods on some of its rivers due to Hurricane David. Floods on some of the eastern and southeastern streams in Puerto Rico were classified as 25-year floods.

Floods hit Texas and Louisiana again on September 17-25. The streams and rivers in the area were already swollen from the July floods and the rain from the hurricanes when 48 to 60 hours of continuous rain fell on coastal counties of eastern Texas and southwestern Louisiana.

Sources: USGS.