How do levees work

In New Orleans, the levees attempt to perform dual duties: On one side of the city, levees protect against floods from the Mississippi River, and on the other side, they help to keep Lake Pontchartrain at bay.

In parts of the Netherlands, dikes stop ocean waters from reclaiming thousands of miles of land, much of which is either at or below sea level. The famous windmills of Holland pump water from behind the dikes and back out to sea to keep the land dry. There are even parts of the Netherlands, called polders , where the Dutch have created new dry land along the sea by diking and draining it.

A levee is typically little more than a mound of less permeable soil, like clay, wider at the base and narrower at the top. These mounds run in a long strip, sometimes for many miles, along a river, lake or ocean. Levees along the Mississippi River may range from 10 to 20 feet 3 to 7 meters tall.

In Holland, they can top 30 feet 10 meters. But there's no set height for levees. Their measurements vary according to the storms the area receives, even if those storms occur only once every hundred or thousand years. Living by the water provides humans with a number of advantages: fertile farm land, transportation, trade and hydroelectric power.

Levees allow humans to enjoy these assets without fear of flooding. But humans have a bad habit of forgetting just how powerful their "strong brown god" really is.

While strolling along the beach or enjoying a picnic by a riverbank, it's easy to forget how powerful Earth's waterways really are -- until floods and storms jar us to remember. In , the Mississippi River swelled under heavy rains, charging through a line of levees and flooding an area the size of Ireland.

In , the North Sea broke through the Netherland's ancient system of dikes and killed thousands. In , New Orleans made international news when Hurricane Katrina breached its levees. Much of the city lies 10 feet 3 meters below sea level. Over the course of the city's history, low-lying, boggy areas have been pumped dry to create new land. Much of this reclaimed land has sunk as it dried out. This water is the lifeline of ecosystems around the world. Freshwater is a precious resource on the Earth's surface.

It is also home to many diverse fish, plant, and crustacean species. The habitats that freshwater ecosystems provide consist of lakes, rivers, ponds, wetlands, streams, and springs. Use these classroom resources to help students explore and learn about these places. Floods are events where water overflows onto land that is typically dry. This can occur when there is a large amount of rain, rapid snow or ice melt, a blast of water onto a coastline during a storm, or the failure of manmade infrastructures, such as dams or levees.

Floods are among the most expensive and frequent natural disasters in the United States, and as the impacts of climate change are more acutely felt, floods are expected to worsen.

In addition to property damage, floods, on average, kill more people than tornadoes, hurricanes, or lightning strikes in the United States each year. Learn more about floods with these resources.

The environmental hazards you face depend on where you live. For example, if you live in northern California you are more likely to be impacted by a wildfire, landslide, or earthquake than if you live in Charleston, South Carolina, but less likely to be hit by a hurricane.

This is because the physical conditions in each place are different. The active San Andreas fault runs through California and causes regular earthquakes, while the warm waters transported by the Gulf Stream can intensify a storm heading for South Carolina. These environmental hazards shape human activity regionally. Learn more about environmental hazards with this curated resource collection. For thousands of years, humans have modified the physical environment by clearing land for agriculture or damming streams to store and divert water.

As we industrialized, we built factories and power plants. For example, when a dam is built, less water flows downstream. This impacts the communities and wildlife located downstream who might depend on that water.

Use these resources to teach your students how humans modify the physical environment and the compounding impacts those changes have.

Catastrophic weather events include hurricanes, tornadoes, blizzards, and droughts, among others. As these massively destructive and costly events become more frequent, scientific evidence points to climate change as a leading cause.

While they can often be predicted, the loss of life and property take an emotional and economic toll on the community impacted.

Explore these resources to teach your students about catastrophic weather events and how they impact every part of the world.

The development of human civilizations was supported by large numbers of people who lived in sparsely-populated rural areas defined by agriculture, fishing, and trade. Over time, as these rural populations grew, cities began to develop. Urban areas are defined by dense populations, the construction of multiple and often large buildings, monuments and other structures, and greater economic dependence on trade rather than agriculture or fishing.

Even the ancient Incan, Egyptian, or Chinese civilizations, changed their environment in order to urbanize. Modern urban cities like New York City, Beijing, Dubai, and Paris are bustling centers of business, entertainment, and trade. However, the modifications humans make to their surroundings in order to urbanize such places can impact the environment in negative ways: pollution, disruption of water flow, deforestation, and desertification. Natural levees Natural levees are composed of earth materials such as silt and sediment and form organically as the water thrusts these aside.

Artificial levees Artificial levees may be built in areas more prone to floods. Permanent levees Permanent levees are constructed using stone, brick, cement, or other tough materials to withstand a flood. Temporary levees Levees that work as a temporary solution for instance, if a permanent levee breaks, or to allow for bridge building are typically wide at the base and narrower near the top. Where to Prevent Flash Flooding With Levees Flash floods are floods that occur very rapidly due to melting snow or ice, thunderstorms, tropical storms, hurricanes, or unusually heavy rain.

Rivers Rivers are susceptible to floods due to being lower. Lakes Lakes expectedly have fluctuating water levels and are therefore not considered as high priority as rivers when it comes to rapid flooding.

Coastline Coastal flash floods occur when tide levels rise higher than expected and heavy rainfall exacerbates them. Around Floodplains Levees can further reduce the risk of flash floods when placed along rivers to separate them from flood plains, allowing less water to come through.

Managing Silt Deposits Adopting a good surface water plan can be very beneficial to managing silt deposits and controlling erosion. Widening Levee Channels Improving river channels includes widening levee systems to prevent inundations caused by flood levels exceeding the levee size. Reinforcing Levees It is crucial to develop a levee project that includes a reinforcement of levees to prevent soil erosion properly.

Preventing Levee Erosion Constructing an outer layer of the levee will help prevent erosion. TrapBag Levees Though similar to sandbags, TrapBag levees are highly superior: just feet of TrapBags can replace 8, conventional sandbags. FAQs How do levees work? What are levees made of? What are the risks associated with levees? How do levees fail? How big can a levee system get? Final Considerations The advantages of levees are colossal and can make all the difference in a catastrophic event.

Leave a Reply Cancel Reply. Share Tweet Share Pin. Call Now. Team Member Nick. In , four major hurricanes hit Florida.

This devastating and relentless display of destruction brought home the reality that beachfront property is extremely vulnerable and is no match for the forces of nature. The most common damage resulting from these inevitable events is soil erosion and storm surge.

Storm surge is the natural force created when high winds and decreased atmospheric pressure cause water to push against the shore. The advancing surge combines with the normal tides and wind-driven waves, creating the hurricane storm tide.

Whether you are looking to protect an existing property or build a new shoreline development, Nucor Skyline can help you evaluate your coastal protection needs.

Nucor Skyline acted quickly to offer design solutions after Hurricane Sandy damaged existing sea walls on the east coast of Florida, rebuilding with AZ to an increased height of 8 feet above the mudline. Download Case Study. Download Brochure.