Water-Supply Paper 2502

Summary of Significant Floods in the United States, Puerto Rico, and the Virgin Islands, 1970 Through 1989

Summary of Significant Floods, 1970 Through 1989, by Year

This section includes brief descriptions of selected signficant interstate and intra-state floods in yearly accounts. Floods described in this section were those with excessive loss of life, excessive damage, extreme discharge or gage height, or those regional in extent. References are provided for these as well as other selected significant floods that occurred during the year. Figures 3-22 in this section depict widespread regional flooding by giving the percentage of streamflow-gaging stations in each State or territory recording greater than the approximate 20-year recurrence-interval flooding during the calendar year.

1987

The first significant flood of 1987 occurred in the Northeastern States and began late in March. Warm temperatures and rainfall accelerated snowmelt runoff. Three separate storms moved through the region during the first week of April. These storms caused severe flooding through Maine, New Hampshire, and Massachusetts (fig. 20). Sixteen streamflow-gaging stations in the three States recorded maximum discharges greater than the 100-year recurrence interval. The hardest hit areas in Maine were the Androscoggin, Kennebec, and Piscataquis River Basins. Record lake levels were reached in at least six flood-control reservoirs in New Hampshire and Vermont. New York was affected by severe flooding along Schoharie Creek, eventually causing failure of a New York State Thruway bridge. The bridge collapse caused 10 deaths and, during preliminary investigations, was attributed to scour around the piers (Zembrzuski, 1990). Total damages were estimated at $100 million in Maine and $65 million in New York (Paulson and others, 1991).

Storms brought excessive amounts of rain to Iowa, Nebraska, Kansas, and Missouri late in May. Extensive flash flooding and record river flooding occurred in southwestern Iowa and southeastern Nebraska on the Nishnabotna and West Nishnabotna Rivers. The same type of weather system moved into Oklahoma and Texas in late May and early June and caused severe flooding. Discharges in the Arkansas and Red River Basins in Oklahoma exceeded the 50- to 100-year recurrence intervals.

Flooding continued in parts of Texas throughout June and into July with significant flooding occurring in southern Texas in mid-June. All major reservoirs in the area reached record levels. On July 16, thunderstorms moved over the San Antonio area producing excessive rainfall. Flooding was concentrated along the Guadalupe River and its tributaries.

Intense rains fell over the divide between the Ohio River and Lake Erie Basins on July 1-2. Rainfall totals were as much as 5 in. in 24 hours in some areas (National Oceanic and Atmospheric Administration, 1987). Other areas had 4 in. of rain in less than 6 hours. Flooding was most severe on the upstream reaches of the Sandusky and Scioto Rivers in Ohio. A few discharges in the area exceeded the estimated 100-year recurrence interval. Four counties in Ohio were declared Federal disaster areas, and the storm caused an estimated $20 million in damages (Mayo and Mangus, 1989).

Central Minnesota was inundated by excessive rains from a succession of thunderstorms during July 20 to 24. At several locations the 100-year, 24-hour record rainfall was exceeded. Many of the suburbs of Minneapolis suffered flash floods.

The worst flood in the history of Chicago, Illinois, struck on August 13 as a result of a succession of thunderstorms that produced excessive rainfall. An official measurement of 9.35 in. in 8 hours (National Oceanic and Atmospheric Administration, 1987) was the greatest for 116 years of record collection. The northern and western metropolitan areas of Chicago bore the brunt of the storm. Significant flash flooding occurred along with general riverine flooding that persisted for many days. Maximum discharges of record occurred at several streamflow-gaging stations on the Des Plaines River and its tributaries. Ponding developed in areas that were normally drained by storm sewers. Areas of northwestern metropolitan Chicago were transformed into large shallow lakes as standing water accumulated to depths of 1 to 3 ft. Damages totalled $62.4 million (Curtis, 1990).

During the first week of September, a tropical depression formed in the Atlantic Ocean and moved over South and North Carolina. Some coastal areas received more than 10 in. of rain in 3 days. Flooding occurred in many areas but was most prevalent in the vicinity of Charleston, South Carolina. The system moved into Virginia on September 5, and produced excessive rainfall that resulted in flooding. Maximum discharges at nine streamflow-gaging stations in Virginia exceeded record highs. Intense rains moved into Maryland and Pennsylvania on September 8 and 9. Flooding in Pennsylvania ranged from flash floods to large-scale river flooding.

A slow-moving storm system produced excessive rain in Puerto Rico in late November and early December. Severe flash floods occurred over the southeastern and eastern parts of the island. The R¬o Valenciano had a discharge with a greater than 30- to 50-year recurrence interval.

Damaging floods occurred in Hawaii on December 12-13, and again on December 31 and January 1, 1988. The later period of flooding was caused by a low-pressure system that developed west of the islands and produced very intense rains as it moved eastward across the islands. Significant flooding occurred on the island of Hawaii. The U.S. Geological Survey streamflow-gaging station on the Wailuha River at Hilo was washed away. More than 20 in. of rain in 24 hours fell over Oahu on New Year's Eve (National Oceanic and Atmospheric Administration, 1987) and produced extensive flash flooding in the valleys of that island. Total damages were estimated at $35 million.

Excessive rains began on Christmas Eve in the south-central United States and continued for 4 days. The most intense rains were centered over Memphis, Tennessee. Rainfall totalled as much as 14 in. in western Tennessee and 12 in. in northeastern Arkansas (National Oceanic and Atmospheric Administration, 1987). The discharges on the Bayou Meto near Lonoke and Big Creek at Goodwin, Arkansas, were between 50- and 100-year recurrence intervals.

Selected References for 1987