Chapter One: Introduction to Flooding

Introduction

Flooding is the most expensive disaster type in the United States. The risk and damage from floods are increasing due to climate change. While flooding seldom destroys buildings completely, it often damages or ruins the contents inside, including appliances, cherished belongings, and even essential electrical systems. In some cases, irreplaceable items, like family photographs or important documents, are lost. The disruption caused by flooding extends beyond financial losses, affecting the emotional well-being of individuals, communities, and even entire regions.

Floods are occurring more frequently and with greater severity due to increasing storm activity, rising sea levels, and heavier rainfall caused by climate change. Homeowners, businesses, and governments face ongoing challenges to protect property, maintain infrastructure, and plan for future risks. To fully understand these challenges, it is essential to explore the definition of flooding, its causes, and its far-reaching consequences.

Defining Flooding

Flooding occurs when water overflows on normally dry land. Flooding can have far-reaching impacts on the environment and human infrastructure. Floodwater can erode land, disrupt ecosystems, degrade water quality, damage homes, and have many more impacts. As a result, the impacts that flooding causes can be catastrophic, affecting communities economically, environmentally and socially.

The most common types of flooding include fluvial flooding, pluvial flooding, flash flooding, storm surge/coastal flooding, and urban flooding. These types of floods are the most common, however, they can each cause significant damage to infrastructure and communities.

Sources and Causes of Flooding

Flooding is caused by rising water levels from many sources (Doswell III, 2003). The most common sources include rivers, streams, and lakes that can overflow due to heavy rainfall or snowfall. Flash floods occur in urban areas when the natural drainage systems cannot handle the downpour. Additionally, man-made causes such as deforestation and poor land use can increase the risk of flooding as well as rid the environment’s natural drainage system and ability to absorb water.

The causes of flooding include:

• Climate change: Climate change plays a significant role in flooding. The warming atmosphere causes melting, and warmer air holds more moisture therefore more rainfall occurs.
• Melting snow and ice: As the temperature of the atmosphere continues to increase this causes snow and ice in the colder regions to melt, which contributes to the rising sea levels.
• Coastal flooding and the rising sea levels: Also known as estuarine flooding. This is when coastal regions are susceptible to flooding caused by storms, hurricanes or rising sea levels due to climate change. Water is pushed further inland, creating a risk for the environment and humans living near.
• Heavy rainfall and storms: In areas all over the world heavy rainfall and storms is one of the main causes of flooding. This occurs when rain falls faster than the ground can absorb it naturally. Surrounding lakes or rivers overflow, contributing to the rainfall and causing widespread flooding, especially when drainage systems become overwhelmed.
• Man-made structures failing: Man-made structures such as dams and levees are made to aid in the control of water flow; however these structures can sometimes fail and contribute to even heavier flooding. Additionally, many drainage systems were not built to withstand the precipitation.. Maintaining, rebuilding or retrofitting these drainage systems is costly and time consuming.

Areas of Highest Impact

The National Flood Insurance Program – NFIP, is required for all mortgage holders in FEMA 1% chance flood zones. The 1% flood zone used to be called the 100 yr flood zone. The term was changed after 2000 due to the confusion of the population thinking a 100 year flood would only happen every 100 years and we know that is not a realistic probability. In fact as the climate is continuing to change with more frequent and more intense storms. Now experts tell us that there is a 26% chance of a flood event in a FEMA 1% flood zone during the life of a standard 30 year mortgage.

Flooding and Louisiana

Flooding is a significant issue in Louisiana due to the geographical and climate conditions. Louisiana’s land is low lying which makes it very susceptible to flooding. The state’s proximity to the Gulf of Mexico also makes it susceptible to hurricanes and tropical storms which contribute to flooding. The Mississippi River and numerous bayous that are present in Louisiana also play a role in flooding due to many factors such as heavy rainfall.

Louisiana has faced many severe flooding events that have impacted both the community and the environment. One of the state’s most devastating hurricanes was Hurricane Katrina in 2005, which made landfall a category 3 storm. This hurricane caused catastrophic flooding in New Orleans and resulted in a levee breaking as well as damage to households, the city’s infrastructure and the loss of many lives (Gibbens, 2019). Another major flood event in Louisiana was The Great Flood in 2016 caused by excessive rainfall that was three times more than the amount left from Hurricane Katrina (Skilton, 2022).

Conclusion

Since the National Flood Insurance program was established in the late 1960’s the annual cost of damages to infrastructure, including roads and bridges as well as our buildings.

Flooding presents many challenges to both communities and the environment. As climate change intensifies and causes intensified rainfall and storm patterns and raised sea levels, flooding grows. The impacts are destructive affecting communities, infrastructure, ecosystems, economies, and individuals. Natural habitats can be permanently destroyed, however with effective planning and investing in resilient infrastructure some of the damage can be reduced. By understanding the causes and consequences of flooding, society can take steps to mitigate its effects.

Definitions

• Flood: An overflow of water onto normally dry land.
• NFIP: National Flood Insurance Program, a federal program providing flood insurance to property owners.
• Climate Change: Changes to the Earth’s atmosphere which has caused an increase in natural disasters, such as flooding.

Review Questions

1. What are the primary causes of flooding?
2. What role does climate change play in increasing flood risk?
3. How did Hurricane Katrina and the Great Flood of 2016 impact Louisiana?
4. How does flooding impact structures and homes?

Bibliography and Links

Doswell III, C. (2003). Flood. Flood – an overview | ScienceDirect Topics. https://www.sciencedirect.com/topics/earth-and-planetary-sciences/flood#:~:text=Flooding%20is%20arguably%20the%20weather,land%20that%20usually%20is%20dry.

Gibbens, S. (2019). Here’s what made Hurricane Katrina one of the worst storms in U.S. history. Retrieved from https://www.nationalgeographic.com/environment/article/hurricane-katrina

Skilton, L. (2022). 2016 floods. Retrieved from https://64parishes.org/entry/2016-floods#:~:text=A%20rainy%20weekend%20in%20August,of%20Louisiana’s%20sixty%2Dfour%20parishes.&text=Flooding%20in%20Baton%20Rouge.