FLOODS

What are floods?

A flood occurs when water overflows or inundates land that's normally dry. This can happen in a multitude of ways.

Types and Causes of Flooding

Most common is when rivers or streams overflow their banks. Torrential rains from decaying hurricanes or tropical systems, a ruptured dam or levee, rapid ice melting in the mountains, or even an unfortunately placed beaver dam can overwhelm a river and send it spreading over the adjacent land, called a floodplain. These floods are called riverine or river floods.

As land is converted from fields or woodlands to roads or parking lots, it loses its ability to absorb rainfall. Urbanization increases runoff 2 to 6 times over what would occur on natural terrain. During periods of urban flooding (also called areal flood), streets can become swift moving rivers, while basements can become death traps as they fill with water.

Winds generated from tropical storms and hurricanes or intense offshore low pressure systems can drive ocean water inland and cause significant flooding. Escape routes can be blocked off and blocked by high water. Coastal flooding or estuarine flooding can also be produced by sea waves called tsunamis, sometimes referred to as tidal waves. These waves are produced by earthquakes or volcanic activity. Most floods take hours or even days to develop, giving residents ample time to prepare or evacuate.

Others generate quickly and with little warning. These flash floods can be extremely dangerous, instantly turning a babbling brook into a thundering wall of water and sweeping everything in its path downstream. Most flash flooding is caused by slow-moving thunderstorms, thunderstorms repeatedly moving over the same area, or heavy rains from hurricanes and tropical storms, however, a dam or levee failure, or a sudden release of water held by an ice jam also can result in flash floods. Furthermore, flash flood-producing rains can also trigger catastrophic mud slides. The two key elements are rainfall intensity and duration. Topography, soil conditions, and ground cover also play an important role. Most flood deaths are due to FLASH FLOODS.

Watch here an interesting video about types of floods.


(Content sources: http://environment.nationalgeographic.com/environment/natural-disasters/floods-profile/; http://education.nationalgeographic.com/encyclopedia/flood/; http://www.weather.gov/dmx/preparefloodintro)
(Images sources: http://www.nssl.noaa.gov/education/svrwx101/floods/types/img/fema-mooreheadmn2009-mikemoore-40572.jpg; http://img2.timeinc.net/people/i/2015/news/150608/texas-flood-1024.jpg; http://i1.liverpoolecho.co.uk/incoming/article6376879.ece/ALTERNATES/s1227b/GAV051213WEATHER-11.jpg; https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgmyP13As70NREriHMaJAnYnYPUW2-NYz4Ap7HPQqNb5XefsrPvk9bHZYUv_y1sQUkofHhFs4D9V9l_8pNjjluhVsB-EWRDDydBe8SQCXotikdSccvMJA2YwLVs4N5boqE5lPfu273pO-M/s1600/Pound+Flash+Flood+-+Rt+689+-+051610+PM+-+Roddy+Addington+PNG.png; http://media.al.com/live/photo/flooding-near-weeks-bay-d0e5c51749227f81.jpg; http://linapps.s3.amazonaws.com/linapps/photomojo/lintvnews.com/photos/2013/09/g8975-deadly-flash-flooding-in-colorado/174345-manitou-springs-colo-d7ed1.jpg; http://i.ytimg.com/vi/fzYk5Tit37A/maxresdefault.jpg)

Some Effects of Flooding

Some negative effects floods may have on people are:

• Drowning
• Homelessness
• Diseases and Infections

On the Economy:

• Infrastructure Damage
• High cost of rebuilding to society and governments
• Damage to Agriculture

On the environment:

• Pollution of water
• Disruption of the Ecosystem

There is also something good about floods, especially those that occur in flood plains and farm fields. Floodwaters carry lots of nutrients that are deposited in the plains. Farmers love such soils, as they are perfect for cultivating some kinds of crops.

Preventive Measures

 Before a flood

•  Install backflow valves or standpipes to prevent sewer lines from backing up.

• Elevate your washer, dryer, water heater, oil tank, furnace and electrical wiring on concrete blocks. Install a sump pump system if you have below-grade floors.
• Landscape with plants and vegetation that resist soil erosion.
• Store irreplaceable family items and important documents somewhere safe.
• Install a flood-detection device that sounds an alarm or calls your phone if it senses water.

During a flood

• Try to stay calm. Keep your family safe, but if you have time:
• Turn off utilities at the main power switch.
• Move valuables, important papers and clothing to upper floors.
• Sanitize your bathtub and sinks and fill them with fresh, clean water in case the water supply becomes contaminated.
• Never try to drive through a flood. Abandon the car and move to higher ground.
• Don't walk through flood areas. Just 6 inches of water can sweep you away.
• Stay away from downed power lines.

After a flood

• After emergency officials have given permission to re-enter your home:
• Check for structural damage before going inside.
• If it’s dark, use a flashlight – not matches, a candle or a lighter.
• Listen for reports to see when drinking water is safe again.
• Don’t turn your power on until an electrician has inspected your system.
• Use your cell phone or other camera to photograph damage, which can help get your claim started sooner.
• Begin initial cleanup as soon as waters recede.  When cleaning, wear a mask, gloves and coveralls to minimize exposure to possible hazardous materials.