Flood Causes

By November 15, 2018Flood Info
Flood Causes

Floods are the #1 natural disaster in the U.S. and worldwide. Damage from floodwaters surpasses the losses caused by hurricanes, tornadoes, or earthquakes – as horrifying and powerful as those catastrophic events are.

The simplest definition of a flood is a large overflow of water onto land that is usually dry. Floods can appear and recede as quickly as it happens with a flash flood. The most catastrophic floods linger for some time, causing loss of life and irreparable damage.

What Causes a Flood?

Flood prevention is a matter of great concern. Floods are primarily a natural phenomenon, but human actions, such as poorly designed infrastructure, can set the stage for a later flood. Understanding the causes is essential to either flood prevention or reducing future flood damage.

Most floods are the result of one of the eight following causes, some natural and some the result of human actions.

1. Heavy Rainfall

For many years, people have designed their infrastructure to move rainwater from where it falls to reservoirs and basins. Most of the time, the system works. No one other than those who support the infrastructure gives a second thought to where the water goes.

Occasionally, a very heavy rain will be too much for the system to handle. The water accumulates faster than it can be taken away. Streets flood. Homes and businesses are flooded by the rising water.

2. Overflowing Rivers

It’s entirely possible to experience river floods without heavy rainfall in your area. People living near rivers are very aware of the fact that if a large storm dumps tremendous quantities of water into the river upstream, then that excess water will flow downstream. This type of flood can be catastrophic but is often predictable and manageable.

Perhaps the best example of this type of flood took place annually in Egypt for thousands of years. The annual flooding of the Nile was a much-anticipated event. The floodwaters left behind incredibly fertile soil that grew the crops needed for trade and to feed their entire civilization.

3. Broken Dams and Levees

Broken dams can cause an incredible amount of damage. In the U.S., most dams and levees were built many years ago. When faced with more water than they can handle, these structures fail, releasing raging waters upon anything in its path. While our infrastructure normally works very well, any structure could potentially fail.

During Hurricane Katrina, the aging levees broke, changing countless lives forever. Thirteen years later, sections of New Orleans’s Ninth Ward still resemble a crumbling ghost town. The story would have been much different if the levees had held.

The Johnstown Flood of 1889 left 2,209 people dead after the South Fork Dam failed. A vast quantity of water exploded through the breaking dam, rushing 14 miles downstream where it totally destroyed the town of Johnstown. Investigation of the disaster eventually resulted in changes to dam management and the U.S. legal system.

4. City Drainage Basins

Many large cities, such as Los Angeles, build concrete drainage basins to contain and manage rainwater. When the rain is especially heavy, the basins can fill up and overflow into low-lying areas.

5. Storm Surges and Tsunamis

Storm surge is one of the most dangerous effects of a hurricane. Powerful winds push water toward the shore, creating life-threatening storm surges that can rage over the tops of homes, sweeping away everything in its path. During Hurricane Katrina, a 34.1 foot High Water Mark was recorded, consisting of a 22 feet high storm surge combined with a 1-foot tide and 11-foot waves. If you live in a two-story house, this storm surge would have totally engulfed your home, crashing over the roof.

Underwater earthquakes can create monstrous waves known as tsunamis. The tsunami that devastated Indonesia in 2004 killed 227,898 people.

6. Lakes, Rivers, and Reservoirs With Steep Sides

A fast runoff of water in a steep-sided narrow channel will rise quickly. This can occur with either natural or man-made channels.

7. Drought and Desert Areas

Trees, shrubs, and other vegetation help to prevent floods by slowing runoff. When there is little vegetation, such as in a desert or drought, the water flows unchecked. A heavy rainfall after a drought can result in a flash flood. Fortunately, reservoirs and basins are normally able to prevent this. In areas where nothing exists to divert the water, flash floods can prove deadly.

8. Melting Ice and Snow

Most people who live near mountains are prepared for spring floods as the snow melts and creates ever-larger streams rushing down the mountain. If there was a much heavier than average snowfall, they know they can expect higher than average water levels and possible floods.

In 2017, the year of Hurricanes Harvey, Irma, and Maria, the average insurance claim after a flood was $91,735. 2018 has also seen substantial flooding. After the recent Florence floods, people living 200 miles from the ocean were flooded. Many never expected to be flooded and had no flood insurance.

Could you afford to rebuild your home and replace all your belongings? Neptune Flood offers peace of mind from the unexpected. If you live in a designated flood zone, your mortgage holder requires flood insurance. However, as happened this year, devastating floods can happen in areas where flooding isn’t anticipated. Also, many homeowners with no mortgages don’t carry flood insurance.

Get a flood insurance quote from Neptune Flood in less than three minutes. Discover how affordable it is. Knowing you’re covered will let you sleep at night.