.jpg) Aerial view of the flood. | |
| Date | July 19, 1977 to July 20, 1977 |
|---|---|
| Location | Johnstown area, Pennsylvania, United States |
| Deaths | 84 |
| Property damage | US$340 million (Johnstown: $137 million; surrounding areas: $213 million)[1] |
The Johnstown flood of 1977 was a major flood which began on the night of July 19, 1977, when heavy rainfall caused widespread flash flooding in Cambria County, Pennsylvania, United States, including the city of Johnstown and the Conemaugh Valley.
On July 19, a deluge of rain hit the Johnstown area during the night. Nearly 12 inches (300 millimetres) of rain fell in 24 hours when a thunderstorm stalled over the region, and six dams in the area over-topped and failed. The largest dam to fail was the Laurel Run Dam, releasing over 101 million U.S. gallons (380,000 cubic meters) of water that poured through the village of Tanneryville, killing 41 people. The combination of the other five dams[2] released another 27 million US gallons (100,000 m3), not counting the water from rains. Well over 128 million US gallons (480,000 m3) of water from the dams alone poured down the valley, and by dawn Johnstown was inundated with six feet (1.8 m) of water. The channel improvements were designed to carry 81,500 cu ft/s (2,310 m3/s), but the 1977 flood discharge was measured as 115,000 cu ft/s (3,300 m3/s).[3] Ron Shawley, executive director of Laurel Highland's Historical Village, returned to Johnstown on July 20 and stated "It was like somebody dropped an atomic bomb on Johnstown" and that "I questioned what kind of force it would take to do that."[4]
- ^ NOAA:1977 damages, Retrieved 2016-01-01
- ^ Dam safety:Number of failures in 1977[permanent dead link], Retrieved 2016-01-01
- ^ NOAA flood discharge, pg. 9, Retrieved 2016-01-01
- ^ "Three Floods Later, Johnstown is Still Standing". AccuWeather. Retrieved 4 January 2016.