Introduction
The 1993 Mississippi River floods were catastrophic, affecting 56,000 square miles, making it the most expensive and one of the worst natural disasters in U.S. history. One of the severe floods that occurred was the Grand Rapids flood of April 24, 1993, caused by flash flooding in northern Minnesota and Wisconsin. The rush of water caused a massive lake effect in the great lake region and created extreme flooding in the Mississippi River Basin. During the disaster, more than 50 lives and billions of dollars worth of property and agricultural crops were lost. The flood was recorded to have caused more than 5 million people to be displaced from their homes. There have been several theories about what caused the great flood of 1993.
Climate Change
The most prominent theory is that climate change was responsible for the 1993 Mississippi River floods. Scientists believe that the warm temperature in the Pacific Ocean combined with an El Nino between February and April 1993 as well as January to March 1992 created an increase in air pressure. This allowed a stronger jet stream that brought heavier rain to the Midwest. In addition, analysis of the 1993 temperatures revealed that the region had higher temperatures than normal and these were two to five degrees Celsius above normal in some areas. With the increase in temperature, the ground became unable to soak up the extra water, which caused flooding in the Mississippi River Basin.
Rainfall
Another factor that contributed to the flooding was the heavy rainfall that the Midwest experienced prior to the flood. 1990 to 1993 had seen high levels of precipitation and in some cases up to three times more than the historical average, leading to large rivers and high ground water levels. It is estimated that the Mississippi River would have flooded anyhow, even without El Nino and climate change factors involved. The heavy rains in August 1992 were responsible for setting the stage for the flood conditions in 1993.
Snow Melt
In addition to the heavy rainfall, there was also a great amount of snow in the Midwest prior to the flooding. As the snow melted, a great amount of water was added to the Mississippi and the other rivers in the region, further increasing the water levels. This was particularly true in the flood of the Grand Rapids, which was the result of runoff from melting snow in northern Minnesota and Wisconsin. The snow melt and the additional runoff from El Nino created the perfect condition for a catastrophic flood.
Levees and Dams
Another factor that contributed to the flooding of the Mississippi River was the inadequate maintenance of the levees and dams that were built along the river. Due to their poor maintenance, the levees and dams were unable to adequately contain the water that was flowing in the river. This caused an increase in the water levels, leading to unprecedented flooding in the region.
Soil Conditions
The soil conditions in the region were also believed to be a factor in the 1993 Mississippi River floods. Prior to the flood, the land was completely deforested and greatly reduced natural absorptivity available in the sand and soil. As a result, the soils could not absorb enough water, leading to large amounts of water flowing onto the land and rivers, which caused the unprecedented flood.
Deforestation
Deforestation was also a contributing factor in the 1993 Mississippi River floods. Much of the nation’s forests had been cut down prior to the flood, reducing the possibility of the land being able to absorb large amounts of water. Without the tall trees, the water that was flowing in the rivers had no place to go and this contributed to the high water levels in the region.
Conclusion
All of these factors contributed to the 1993 Mississippi River floods. Climate change, the heavy rainfall, snow melt, inadequate levee and dam maintenance, the soil conditions, and the deforestation all worked together to create the flood conditions that were seen in the region. It is estimated that the flooding caused over 50 deaths, billions in property damage, and over 5 million people to be displaced from their homes.
