East Kentucky is susceptible to different types of flooding hazards, which can occur for many different reasons. One type of common flooding around east Kentucky is when river and stream banks cannot contain the amount of water flowing through them and water spills over the banks, often affecting roads, homes, businesses, etc. The rugged, steep terrain of east Kentucky allows for many small rivers and streams because of all the valleys that are between ridgetops. During a heavy rain event, all of the water that falls on the steep hillsides has to have a place to collect, flowing into streams and rivers. Continuous rainfall, or periods of heavy rainfall often cause more water to flow into the streams and rivers than they can handle. Once the water flows over the banks of streams or creeks, a flood is said to have occurred. Sometimes impacts are small and rather short lived, however, impacts have been known to be quite large and prolonged for the most prolific floods. One such flood was the March 1997 flooding of the Ohio River.
Many times, the late Winter to early Spring time frame is especially prone to flooding because you can combine snow melt from previous snow storms with heavy rain producing storm systems. An already saturated ground will have trouble handling large amounts of water in the this situation. Between March 1st and March 3rd of 1997 as much as 6-12 inches of rainfall fell over portions of northern Kentucky, southern Indiana, and southern Ohio. As a result, flash flooding, areal flooding, and river flooding occurred in basins along the Ohio River Valley. As heavy rain fell from March 1st through 3rd, small scale and short-lived flash flooding events occurred as saturated ground left nowhere for ample amounts of water to flow and water ponded on roads and low lying areas. Flash flooding is the most dangerous type of flooding and is responsible for the most deaths in the U.S. per year than any other thunderstorm related hazard. The reason for this is how quickly a flash flood can occur and how intense the flowing water can be. Many times, people underestimate how powerful water flowing across a roadway can be and get swept away as they try to drive across it. Many drownings occur because of this.
While the number of fatalities can vary dramatically with weather conditions from year to year, the national 30-year average (1977-2006) for flood deaths is 99. That compares with a 30-year average of 61 deaths for lightning, 54 for tornadoes and 49 for hurricanes.
National Weather Service data also shows:
Source: (National Weather Service Southern Region Headquarters: Turn Around Don't Drown)
(Picture courtesy of NOAANEWS: Do not try to drive cars across flooded roadways..."Turn Around, Don't Drown!!")
While flash flooding was occurring, other types of flooding also occurred in areas that were not receiving heavy and intense rainfall for long periods of time. Urban and small stream flooding occurred in areas that received large amounts of rainfall; however the rain was not quite heavy enough or concentrated enough to produce flash flooding, but flooded low lying areas such as low water crossings and farmland along the banks of streams and creeks. An advisory is issued for these situations as urban areas and small streams are the first locations that are likely to flood when large amounts of water fall on an area. Areal floods generally occur several hours after heavy rain ends as water that fell drains very slowly reaching larger streams and creeks and, often water ponds or collects in an area. Generally, a flash flood is considered to last up to 6 hours after a heavy rainfall event ends. Flooding that is occurring more than 6 hours after heavy rainfall ends is considered areal flooding and areal flood warnings are used.
(Picture courtesy of: NOAA Southern Region Headquarters: Turn Around, Don't Drown)
Finally, the largest and most impactful flooding that occurred in early March 1997 was the river flooding. All of the water the fell over the Ohio Valley had to collect somewhere, and that somewhere was the Ohio River. As the river filled up, tributaries that fed into the Ohio backed up because there was nowhere for water to flow. The town of Falmouth, Kentucky in Pendleton county was completely under water and almost completely destroyed. Over 500 million dollars in damage was done as 14,000 homes were damaged or destroyed and over 20,000 homes and businesses applied for federal disaster relief. In Ohio and Kentucky, 26 deaths were related to the flooding, including 21 in Kentucky and 5 in Ohio.
Source: (Dept. of Commerce Service Assessment: Ohio River Valley Flood of March 1997)
The pictures below represent the Ohio River Valley during normal conditions (Top) the year before the 1997 flood. The bottom picture shows the swollen Ohio River and its tributaries on March 6th 1997, several days after the heavy rain fell.
Image courtesy of: NOAA/NESDIS