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Floods are one of the most commonly occurring natural hazards in the United States. Their effects can be local, impacting a neighborhood or community, or can occur in large scale, affecting entire river basins and several states. About 3,800 towns and cities in the United Sates with populations of more than 2,500 lie on floodplains. The National Weather Service has documented some ninety-two flood deaths per year in the United States since 1903. This figure does not include flood-related deaths associated with Hurricane Katrina (2005). Since 1997, more than half (about fifty-seven percent) of all flood deaths have been vehicle-related fatalities. Throughout its history, Arkansas has been drastically affected by floods, with the most notable being in 1927 and 1937.
The reasons for flooding relate to climatology, topography, and size of river basin. Arkansas frequently sees a pattern of subtropical moisture flows from the Gulf of Mexico. As this moisture lifts from the Gulf and encounters mountainous terrain, it triggers convective instability, which often leads to large, multi-celled, persistent thunderstorm systems. These can produce significant rain events resulting in flooding. Rivers that begin in highland areas of the Ozark or Ouachita mountains and flow into the Mississippi Delta (White, Black, and St. Francis rivers) or the Gulf Costal Plain (Ouachita and Little Missouri rivers) are particularly prone to large-scale flooding by the time they reach the lowlands. High flows on the Arkansas, Red, and Mississippi rivers are most often the result of heavy rains that have saturated the ground over an extensive area. Persistent thunderstorm activity in Arkansas can trigger large-scale flood events along these big river basins.
Flash flooding is perhaps the most dangerous type of flooding to occur, as it can develop quickly and affect an area without warning, as in the 2010 Little Missouri flood at the Albert Pike Recreational Area. This type of flood is produced by heavy downpour rains in steep terrain and results in a wall of water that carries rocks, mud, and other debris and sweeps away everything in its path. Overland flooding, covering a wide area, may occur during a levee break. Emergency dam releases or dam failure can also cause extensive, sudden flood disasters similar to flash floods.
Natural flooding is essential and beneficial to wetlands and bottomland forests. Lower floodplain levels are naturally flooded each year in Arkansas about forty percent of the time. Historically, however, much of the problem with flood disasters has resulted from the corruption of natural ecosystems and encroaching development on floodplains.
Congress passed the first Flood Control Act in 1917, which appropriated $45 million for flood control on the lower Mississippi. Prior work had consisted mostly of small-scale, local, private efforts. What federal levee work had been done was tied to navigational interests. After the passage of the Flood Control Act of 1928 (spurred by widespread and disastrous flooding in 1927), federal work on flood control increased dramatically. Studies of river tributaries, along with prospective reservoir and levee projects, began to multiply as Congress approved civil works projects under the U.S. Army Corps of Engineers. The U.S. Geological Service and National Weather Service increased efforts in river stage monitoring and flood science. In 1968, the National Flood Insurance Act offered new flood protection programs to homeowners. Seeking to decrease the many agencies with which state and local governments were forced to work, the National Governor’s Association asked President Jimmy Carter to centralize federal emergency functions. He responded by issuing Executive Order 12127 in 1979. This merged many separate disaster-related responsibilities into the Federal Emergency Management Agency (FEMA). Today, FEMA is largely responsible for the implementation of federal hazard-reduction policies and floodplain management.
Despite these efforts, damage from flooding continues to escalate. This trend is mainly due to increased development on floodplains as government programs began offering flood insurance and flood relief assistance.
Decadal Annual Average of National Flood Damage Estimates—National Weather Service Data:
Average Annual Estimate in Current U.S. $
(data from 1980–1982 not available)
U.S. Geological Survey (USGS) flood damage estimates in 2006 put average annual national losses at about $6 billion and 140 deaths. Total claim payments from the National Flood Insurance Program for Arkansas alone in fiscal year 2010 totaled $17.3 million. The number of policies issued by the program in Arkansas grew by five percent in fiscal year 2010. From 1965 to 2004, the counties in Arkansas to receive the most presidential disaster declarations (thirteen to fifteen) were: Columbia, Craighead, Independence, Jackson, Poinsett, and Pulaski. Eighty percent of all presidential disaster declarations involve floods.
Historic Arkansas FloodsThe following table indicates historic flood years on Arkansas’s seven largest rivers using USGS data from Magnitude and Frequency of Floods in Arkansas (1995). The data for these rivers was reprinted from an earlier report and ended with years 1980–1984. Stage levels and flows from numerous gauging stations were compared. In most cases, only floods from about two feet over bank full or higher were included. The number of gauge stations on a river and their dates of record varied. In some years, floods occurred only at one station, while in other years, flooding occurred at all stations on a given river.
Key: * denotes significant flood; † denotes beginning year of data; ‡ denotes ending year of data
St. Francis River