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Living near water is a wonderful thing—except once there’s a flood. So people develop levees. A levee is a natural or artificial wall that block water from going wherein we don’t desire it to go. Dams may be provided to increase obtainable land because that habitation or draw away a body of water so the fertile soil the a river or sea bed might be supplied for agriculture. They protect against rivers native flooding cities in a storm surge. But if a levee breaks, the aftermath can be disastrous.

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Levees space usually make of earth. The natural movement of a human body of water pushes sediment to the side, creating a herbal levee. The financial institutions of a flow are regularly slightly elevated from the flow bed. The banks kind levees make of sediment, silt, and other products pushed aside by the flowing water. Dams are generally parallel come the way the flow flows, so dams can aid direct the circulation of the river.

Levees can also be artificially created or reinforced. Synthetic levees space usually built by piling soil, sand, or rocks ~ above a cleared, level surface. In places where the flow of a flow is strong, levees may likewise be make of block of wood, plastic, or metal. Wherein the area next to a flow or other body that water is in details danger, dams may even be reinforced through concrete.

People have actually been building and also reinforcing levees since the start of civilization. As early as 2500 BCE, the Indus valley Civilization, v urban centers in what is this particular day Mohenjo Daro and Harappa, Pakistan, used dams to safeguard land close to the Indus River. Farmers to be able to grow crops like cotton and also rice.

In addition to creating living an are and cropland, levees can also carry out a measure of protection from invaders. Levees can make a river favor a moat, preventing people from conveniently invading are on the various other side. Destroying levees can additionally stop invading forces. In 1938, Chinese leaders intentionally broke levees ~ above the Yellow flow to avoid the Japanese military from advancing. Much more than 500,000 people, Japanese and Chinese, passed away in the result flood.

Artificial dams need to it is in protected. They have to stand up to erosion, or attract away, by the nearby water. Sometimes, trees and plants favor Bermuda grass space planted near dams to anchor the soil. Designers need come maintain dams with structural occupational to reinforce the boundaries.

In emergencies, momentary levees can be make of sandbags. These soak up the water and usually avoid excess water from seeping past the sand.

Artificial dams prevent flooding. But they also create a brand-new problem: dams squeeze the flow of the river. Every the river’s strength is flowing with a smaller sized space. Water level are higher and water operation faster. This puts much more pressure on levees downstream and makes the water more daunting to control. If levees break, it likewise makes include the flood more difficult.

Since the 18th century, dams have safeguarded Louisiana and other nearby states from flooding through the Mississippi River. As soon as Hurricane Katrina struck brand-new Orleans in 2005, the levees could not stand up to the storm surge. The levees broke, and water submarine 80 percent of the city.

Levees ~ above the Sea

Although most levees exist to manage rivers, they can also exist on the coast. The country of the Netherlands has fancy system of dikes, levees, and also dams come hold ago the north Sea. Land because that farms, industry, and also residential use has actually been produced from land that was once the ocean floor.

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The only of Fundy, which boundaries the districts of new Brunswick and Nova Scotia, Canada, has actually one the the highest tidal arrays in the world. The tidal selection reaches much more than 17 meter (55 feet) in some places. To do the many use of floor that would certainly otherwise be underwater during high tide, Canada has created levees along parts of the only of Fundy.