Texas, you may have noticed, is in trouble, and Louisiana is a lake. The inundation of several of the southern states of the US can be traced to the arrival of a tropical storm, Allison, ashore late last week, which resulted in falls of 20 to 30 inches of rain over a short period in some areas.
The ensuing floods have caused significant loss of life, and damage to property estimated at many millions of dollars. But there have been worse American flooding disasters. The most horrendous occurred in September 1900, when a massive storm surge, associated with a hurricane, inundated Galveston Island on the Texas coast of the Gulf of Mexico, an area affected by the present devastation; in this flood, 6000 people lost their lives.
But the Johnstown Flood of 1889, almost comparable in terms of loss of life, was caused, like recent happenings, by very heavy rain. At the time of the tragedy, Johnstown, Pennsylvania, had a population of slightly over 30,000. Nearly 40 years before, in 1852, a dam had been built on the Conemaugh river some miles upstream of the town to supply water for the proposed Pennsylvania Canal. The canal project was later abandoned in favour of a railway, but the dam remained, and the reservoir behind it was used for many years for recreational activities.
Rain began on the evening of May 30th, 1889. It continued steadily through the night, becoming heavier as time went by, and falling in amounts greater than anyone in the area had ever seen before. By the following morning the Conemaugh had burst its banks, leaving Johnstown under several feet of water.
By 3 p.m. on May 31st the pressure of millions of tons of water became too great for the restraining earthworks of the Johnstown dam. The structure dissolved very suddenly into a great mass of mud, and the contents of the vast reservoir surged down the valley on to the helpless population of the town below. It took only 45 minutes to empty, the swirling waters sweeping away everything in their path. The debris carried along by the deluge created a vast 32acre island in the centre of Johnstown, and this pile of devastation became a temporary refuge for many of those who survived the first surge of the flash flood. But their sanctuary was brief; the debris ignited, and many of those who had survived the flood perished in the ensuing fire. The final death toll was greater than 2,000.