Floods and flash floods are two leading severe weather-related killers in the United States. In Ohio alone, there have been 35 flood-related deaths during the last 10 years.
Approximately 90 percent of all federally declared disasters include flooding. Not all disasters are of the magnitude to receive a federal or presidential declaration.
During the summer of 2003, severe thunderstorms and strong winds caused six flood-related deaths in Ohio. Butler County received a federal SBA (Small Business Administration) declaration in June for flooding, and the state received two federal disaster declarations for 23 qualifying storm-affected counties.
During the 4th of July weekend, severe storms and strong winds moved across the majority of the state with substantial flooding in the northwest and west-central portions of Ohio. Six to 12 inches of rain poured on these parts for five days. What began as a small stream and flash-flooding event led to major river flooding along the Great Miami and St. Mary's rivers. Several hundred people were evacuated, with dozens of homes and businesses sustaining major damages. A federal disaster was declared for Mercer, Van Wert, Auglaize, Shelby, Logan and Darke counties.
In late July, heavy rains, strong winds and tornado hit the northeast portion of the state, initially impacting nine counties. Two men drowned in an underground parking garage of a condominium complex in Hudson, Ohio and a 10-year-old boy drowned after being sucked into a culvert. More that 300 homes in Summit County sustained enough damage to be declared destroyed or uninhabitable. As many as 1,000 other homes and businesses sustained minor damage. Damage estimates topped $100 million.
Though "special flood hazard areas" have been mapped for most Ohio communities, about one in four floods occur in areas with a low to moderate risk of flooding. U.S property damage from flooding now exceeds $1 billion every year.
Three types of flooding occur in Ohio:
1. General River Flooding occurs after long-term heavy rain, snow melt or a combination of the two. It usually occurs slowly, allowing more time to move people and property to safety.
2. Flash Flooding named for its sudden, in-a-flash occurrence, is deceptively dangerous. In a few moments, the flow in a small, almost unnoticed stream or ditch can become a deadly and destructive torrent. Then, just as suddenly, it can drop back to a normal flow. Flash flooding can occur anywhere that the amount of water exceeds an area's capability to absorb it or convey it within the banks of existing channels.
3. Urban and Small Stream Flooding is a subtle flood threat. It can occur when heavy rain falls in an urban or rural area, resulting in flooded streets, underpasses, drainage ditches in an urban area or creeks in rural areas. It is not normally a threat unless motorists drive through the flooded road or children play in flooded drainage ditches. Small stream flooding can be hazardous if persons get too close to a swollen creek.