Many of us have this idea that floods (or flooding) is simply, too much water around your house. People think that can be fun. Wrong. Flooding is a lot more than that.
Flooding is extremely dangerous and has the potential to wipe away an entire city, coastline or area, and cause extensive damage to life and property. It also has great erosive power and can be extremely destructive, even if it is a foot high.
It is a natural event or occurrence where a piece of land (or area) that is usually dry land, suddenly gets submerged under water. Some floods can occur suddenly and recede quickly. Others take days or even months to build and discharge.
When floods happen in an area that people live, the water carries along objects like houses, bridges, cars, furniture and even people. It can wipe away farms, trees and many more heavy items.
Failing to evacuate flooded areas, entering flood waters, or remaining after a flood has passed can result in injury or death. Flooding is a temporary overflow of water onto land that is normally dry. Floods are the most common natural disaster in the United States. Floods may:
- Result from rain, snow, coastal storms, storm surges, and overflows of dams and other water systems.
- Develop slowly or quickly – Flash floods can come with no warning.
- Cause outages, disrupt transportation, damage buildings, and create landslides.
IF YOU ARE UNDER A FLOOD WARNING, FIND SAFE SHELTER RIGHT AWAY
- Do not walk, swim, or drive through flood waters. Turn Around, Don’t Drown!
- Just six inches of moving water can knock you down, and one foot of moving water can sweep your vehicle away.
- Stay off of bridges over fast-moving water.
- Determine how best to protect yourself based on the type of flooding.
- Evacuate if told to do so.
- Move to higher ground or a higher floor.
- Stay where you are.
CAUSES OF FLOODING
Each time there are more rains than the drainage system can take, there can be floods. Sometimes, there is heavy rain for a very short period that result in floods. In other times, there may be light rain for many days and weeks and can also result in floods.
Rivers can overflow their banks to cause flooding. This happens when there is more water upstream than usual, and as it flows downstream to the adjacent low-lying areas (also called a floodplain), there is a burst and water gets into the land.
Hurricanes, Strong winds in coastal areas
Sea water can be carried by massive winds and hurricanes onto dry coastal lands and cause flooding. Sometimes this is made worse if the winds carry rains themselves. Sometimes water from the sea resulting from a tsunami can flow inland to cause damage.
Wrightsville Beach in North Carolina USA, September 14, 2018
A massive North Atlantic Hurricane that covered a distance of about 6,500km made landfall. The hurricane was an unusually slow-moving one, and stayed over that location for a long time, with non-stop rains. This led to catastrophic flooding, as the land was already saturated from the wet summer. Communities such as Wilmington were cut off. More than 40 people died from the hurricane and massive destruction of homes and infrastructure occurred.
TYPES OF FLOODS
Some would like to see the causes of floods as types of floods, but on this page we shall look at three major flood types: Flash floods, Rapid on-set floods and Slow on-set floods.
Rapid on-set floods
Slow on-set floods
EFFECTS OF FLOODING
Floods can have devastating consequences and can have effects on the economy, environment and people.
During floods (especially flash floods), roads, bridges, farms, houses and automobiles are destroyed. People become homeless. Additionally, the government deploys firemen, police and other emergency apparatuses to help the affected. All these come at a heavy cost to people and the government. It usually takes years for affected communities to be re-built and business to come back to normalcy.
Did you know that the cost of all floodings in the USA in 2011 was $8,640,031,956 (approx 8.5B USD) — http://www.nws.noaa.gov/hic/
The environment also suffers when floods happen. Chemicals and other hazardous substances end up in the water and eventually contaminate the water bodies that floods end up in. In 2011, a huge tsunami hit Japan, and sea water flooded a part of the coastline. The flooding caused massive leakage in nuclear plants and has since caused high radiation in that area. Authorities in Japan fear that Fukushima radiation levels are 18 times higher than even thought.
Additionally, flooding causes kills animals, and others insects are introduced to affected areas, distorting the natural balance of the ecosystem.
People and animals
Many people and animals have died in flash floods. Many more are injured and others made homeless. Water supply and electricity are disrupted and people struggle and suffer as a result. In addition to this, flooding brings a lot of diseases and infections including military fever, pneumonic plague, dermatopathia and dysentery. Sometimes insects and snakes make their ways to the area and cause a lot of havoc.
There is also something good about floods, especially those that occur in floodplains 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.
PREPARE FOR A FLOOD
Floods are unpredictable and destructive, and they can happen in regions that have never seen rain.
They can cause death and injuries, isolate communities, damage major infrastructure, cut essential services, destroy property and livelihoods.
In Western Australia (WA), flooding could happen anywhere, at any time and from a variety of water sources including rivers and creeks, storm tides, overflowing catchments and due to heavy rainfall caused by cyclones.
Apart from the physical damage to property, experiencing a flood can be an extremely emotional time. If you are not prepared for the possibility of a flood, recovery can be slow, stressful and costly.
A few hours spent making your home secure, preparing an emergency kit and flood plan can help you to survive the affect of a flood.
You need to:
- Understand the flood risk to your area
- Prepare your home and property
- Respond when water comes
- Recover after a flood
You can prepare for flooding in a number of ways:
- Check with your local council about local flood plans or records which detail problem areas
- Ask authorities about relocation routes and centres
- If your area is flood prone consider alternatives to carpets
- Prepare an emergency kit
- Prepare a household flood plan
- Keep a list of emergency telephone numbers on display
- Check your insurance policy to see if you are covered for flood damage?
If flooding is due make your safety a priority and if you have time try to prepare your property:
- Secure hazardous items
- Roll up rugs, move furniture, electrical items and valuables to a higher level
- Place important personal documents, valuables and vital medical supplies into a waterproof case in an accessible location
- If you are relocating, take your pets with you if it is safe to do so. If not provide adequate food and water and move them to a safer place
- Monitor Bureau of Meteorology (BoM) forecasts and warnings online and listen to your local ABC Radio
Relocating to safer ground:
If rising waters threaten your home and you decide to move to a safer location, tell the police, your nearest State Emergency Service (SES) unit or your neighbours of your plans to move.
- Monitor your local radio for warnings and advice
- Pack warm clothing, essential medication, valuables and personal papers in waterproof bags along with your emergency kit.
- Raise furniture, clothing and valuables onto beds, tables and into roof space place electrical items in the highest place
- Empty freezers and refrigerators, leaving doors open to avoid damage or loss if they float.
- Turn off power, water and gas and take your mobile phone
- Whether you leave or stay, put sand bags in the toilet bowl and over all laundry/bathroom drain holes to prevent sewage backflow
- Lock your home and take recommended relocation routes for your area
- Do not drive into water of unknown depth and current
Too late to leave:
- Monitor your local radio for warnings and advice
- Get to higher ground
- Switch off electricity and gas supplies to your home
- Prepare to move vehicles, outdoor equipment, garbage, chemical and poisons to higher locations
- Prepare for the well being of pets
- Raise furniture above likely flood levels
- Check your emergency kit
- Do not allow children to play in or near floodwaters
- Avoid entering floodwaters,. if you must do so, wear solid shoes and check depth and current with a stick
- Stay away from drains, culverts and water over knee deep.
- Do not use gas or electrical appliances that have been in floodwater until checked for safety
- Do not eat food that has been in floodwaters
- Boil tap water until supplies have been declared safe.
During a Flood
- Depending on where you are, and the impact and the warning time of flooding, go to the safe location that you previously identified.
- If told to evacuate, do so immediately. Never drive around barricades. Local responders use them to safely direct traffic out of flooded areas.
- Listen to EAS, NOAA Weather Radio, or local alerting systems for current emergency information and instructions.
- Do not walk, swim, or drive through flood waters. Turn Around. Don’t Drown!
- Stay off bridges over fast-moving water. Fast-moving water can wash bridges away without warning.
- If your vehicle is trapped in rapidly moving water, then stay inside. If water is rising inside the vehicle, then seek refuge on the roof.
- If trapped in a building, then go to its highest level. Do not climb into a closed attic. You may become trapped by rising floodwater. Go on the roof only if necessary. Once there, signal for help.
- Listen to the radio or television for information.
- Be aware that flash flooding can occur. If there is any possibility of a flash flood, move immediately to higher ground.
- Be aware of stream, drainage channels, canyons and other areas known to flood suddenly. Flash floods can occur in these areas with or without typical warnings such as rain clouds or heavy rain.
- Be prepared to evacuate.
- Secure your home. If you have time, bring in outdoor furniture. Move essential items to an upper floor.
- Turn off utilities at the main switches or valves if instructed to do so. Disconnect electrical appliances. Do not touch electrical equipment if you are wet or standing in water.
- Follow orders to evacuate.
- Do not walk through moving water. Six inches of moving water can make you fall. If you have to walk in water, walk where the water is not moving. Use a stick to check the firmness of the ground in front of you.
- Do not drive into flooded areas. If floodwaters rise around your car, abandon the car and move to higher ground if you can do so safely.
- Do not camp or park your vehicle along streams, rivers or creeks, particularly during threatening conditions.
After a Flood
- Use local alerts and warning systems to get information and expert advice.
- Avoid moving water.
- Stay away from damaged areas unless your assistance has been requested by police, fire, or a relief organization.
- Stay off the roads and out of the way of emergency workers.
- Listen for local warnings and information.
- Return home only when authorities indicate it is safe.
- If you must walk or drive in areas that have been flooded.
- Stay on firm ground. Moving water only 6 inches deep can sweep you off your feet. Standing water may be electrically charged from underground or downed power lines.
- Flooding may have caused familiar places to change. Floodwaters often erode roads and walkways. Flood debris may hide animals and broken bottles. Avoid walking or driving through it.
- Be aware of areas where floodwaters have receded. Roads may have weakened.
- Stay out of any building if it is surrounded by floodwaters.
- Use extreme caution when entering buildings; there may be hidden damage, particularly in foundations.
- Look after yourself and your family as you begin the recovery process.
- Avoid floodwaters; water may be contaminated by oil, gasoline or raw sewage.
- Service damaged septic tanks, cesspools, pits and leaching systems as soon as possible. Damaged sewer systems are serious health hazards.
- Listen for news reports to learn whether the community’s water supply is safe to drink.
- Clean and disinfect everything that got wet. Mud left from floodwaters can contain sewage and chemicals.
- Turn off the electricity at the main breaker or fuse box, even if the power is off in your community. That way, you can decide when your home is dry enough to turn it back on.
- Contact your insurance agent to discuss claims.
- Listen to your radio for information on assistance that may be provided by the state or federal government or other organizations.
- If you hire cleanup or repair contractors, check references and be sure they are qualified to do the job. Be wary of people who drive through neighborhoods offering help in cleaning up or repairing your home.
- Know the emergency plans for your area.
- Familiarize yourself with these terms to help identify a flood hazard:
- Flood Watch—Flooding is possible. Tune in to NOAA Weather Radio, commercial radio or television for information.
- Flash Flood Watch—Flash flooding is possible. Be prepared to move to higher ground; listen to NOAA Weather Radio, commercial radio or television for information.
- Flood Warning—Flooding is occurring or will occur soon; if advised to evacuate, do so immediately.
- Flash Flood Warning—A flash flood is occurring; seek higher ground on foot immediately.
- Research additional information about floods, beginning with the following resources.
- Repairing Your Flooded Home
- After a Flood: The First Steps
- Homeowner’s Guide to Retrofitting: Six Ways to Protect Your House from Flooding
- About the Flood: Elevating Your Floodprone House
- Protecting Building Utilities From Flood Damage
- National Weather Service
- U.S. Environmental Protection Agency
- Centers for Disease Control and Prevention
Methods of Flood Prevention
Humans cannot stop the rains from falling or stop flowing surface water from bursting its banks. These are natural events, but we can do something to prevent them from having great impact. Here are a few.
Sea / Coastal Defence Walls
Sea walls and tide gates have been built in some places to prevent tidal waves from pushing the waters up ashore. In some areas too, sand bags are made and placed in strategic areas to retain floodwaters.
In some places, retaining walls levees, lakes, dams, reservoirs or retention ponds have been constructed to hold extra water during times of flooding.
It is important that builders acquire permission before buildings are erected. This will ensure that waterways are not blocked. Also, drainage systems must be covered and kept free from objects that chock them. This way, water can quickly run through if it rains and minimize any chance of town flooding. Drainage systems should also be covered to prevent litter from getting into them.
Trees, shrubs and grass help protect the land from erosion by moving water. People in low-lying areas must be encouraged to use a lot of vegetation to help break the power of moving flood water and also help reduce erosion.
In many developing countries, drainage systems are chocked with litter and people have little knowledge of the effects that can have during a rain. When it rains, waterways and culverts are blocked by massive chunks of litter and debris, and water finds its way into the streets and into people’s homes. Education is therefore very important, to inform and caution people about the dangers of floods, what causes floods, and what can be done to minimise its impact.
These are small reservoirs built and connected to waterways. They provide a temporary storage for floodwaters. This means in an event of flooding, water is drained into the basin first, giving people more time to evacuate. It can also reduce the magnitude of downstream flooding.
Did you know?
Here are a few interesting things you can share with your friends about floods.
In Australia, floods are the most expensive type of natural disaster with direct costs estimated over the period 1967-2005 averaging at $377 million per year (calculated in 2008 Australian dollars). http://www.chiefscientist.qld.gov.au/publications/understanding-floods/consequences.aspx
Flood losses in the United States averaged $2.4 billion per year for the last decade. Floods are the number one natural disaster in the United States. http://www.floodsmart.gov/toolkits/spanish/downloads/english/facts-and-figures.pdf
A physically defined route (path) where water or run-off passes into an outlet or terminus. (Terminus can be the ocean or bigger water body) This includes rivers, creeks, tributaries, stream or estuary. A waterway may be dry, but will soon be full of moving water when there are rains.
Peak water level / flood peak – The highest level that water in a waterway reaches during a flood. This is a measure of the size (or magnitude) of a flood.
Runoff – Each time there is more water on a piece of land than it can infiltrate the soil, the excess water will flow to find its own level. The excess water flow is what we call ‘Runoff” Sometimes the rains come down heavily and the soil (or earth) cannot absorb the water quick enough. This causes the rain water to flow as a runoff.
Never swim or play around in flood water. It may contain chemicals, bacteria and disease causing organisms. If your skin comes in contact with floodwater, make sure to wash it with soap and disinfected water because the contents are unknown.
Communities particularly at risk are those located in low-lying areas, near water, or downstream from a dam.
Based on Floodsmart, a 2,000 square foot home undergoing 12inches of water damage could cost more than $50,000.
Never drive into a flooded roadway or drive through flowing water because just 2 feet of water can float a large vehicle and sway it away.
Sometimes, local emergency officers are able to tell if there is a possibility of flood during a rain or high tide at the shore. When this happens, they keep a close eye on events and inform the public about it. This is called a Flood Watch.
A flood warning is when an official announcement is given (by TV, Radio, Text Message or Phone, Email or other means) of an impending flood or an already flood that has already occurred. A flood warning instructs people to move to higher ground or take immediate precautions to avoid drowning or to minimize damage to property.
Levee: A manmade structure to contain or prevent water from moving past a certain point.