Rain & Flood Safety
Floods are one of the most common hazards, however, not all floods are alike. Some floods develop slowly, while others can develop in just a few minutes without visible signs of rain. Additionally, floods can be local, impacting a neighborhood or community or they can be very large impacting entire river basins and regions.
Overland flooding, the most common type of flooding event, typically occurs when waterways such as rivers or streams overflow their banks. This type of flooding is a result of rainwater or a possible levee breach and causes flooding in surrounding areas. It can also occur when rainfall or snowmelt exceeds the capacity of underground pipes, streets and drains designed to carry flood water away from urban areas.
Be aware of flood hazards no matter where you live or work, but especially if you are in low-lying areas, near water, behind a levee or downstream from a dam. Even very small streams, gullies, creeks, culverts, dry streambeds or low-lying ground that appear harmless in dry weather can flood.
Causes of flooding
- FLASH FLOODS – Flash floods can occur within a few minutes or hours of excessive rainfall, a dam or levee failure, or a sudden release of water held by an ice jam. Flash floods often have a dangerous wall of roaring water carrying rocks, mud, and other debris.
- TROPICAL STORMS AND HURRICANES – Hurricanes pack a triple punch: high winds, soaking rain, and flying debris. They can cause storm surges to coastal areas, as well as create heavy rainfall which in turn causes flooding hundreds of miles inland. When hurricanes weaken into tropical storms, they generate rainfall and flooding that can be especially damaging since the rain collects in one place.
- SPRING THAW – During the spring, frozen land prevents melting snow or rainfall from seeping into the ground. Each cubic foot of compacted snow contains gallons of water, and once the snow melts, it can result in the overflow of streams, rivers, and lakes. Once spring storms are added, oftentimes the result is serious spring flooding.
- HEAVY RAINS – Several areas of the world are at heightened risk for flooding due to heavy rains. This excessive amount of rainfall can happen throughout the year, putting your property at risk.
- LEVEES & DAMS – Levees are designed to protect and hold back a certain level of water. However, levees can and do fail, and when they fail, they can fail catastrophically. The weakening of levees over time, or as a result of weather events exceeding the levee’s level of support, can cause the levee to be overtopped or breached increasing the chance of flooding.
- NEW DEVELOPMENT – Construction and development can change the natural drainage and create brand new flood risks. That’s because new buildings, parking lots and roads mean less land to absorb excess precipitation from heavy rains, hurricanes and tropical storms.
BEFORE A FLOOD
Even if you feel you live in a community with a low risk of flooding, remember that anywhere it rains, it can flood. Just because you haven’t experienced a flood in the past, doesn’t mean you will not in the future. Flood risk isn’t just based on history, it’s also based on a number of factors including rainfall, topography, flood-control measures, river-flow / tidal-surge data, and changes due to new construction and development.
To prepare for a flood, you should:
- Build an emergency kit and make a family communications plan.
- Avoid building in a floodplain unless you elevate and reinforce your home.
- Elevate the furnace, water heater and electric panel in your home if you live in an area that has a high flood risk.
- Consider installing ‘check valves’ to prevent flood water from backing up into the drains of your home.
- If feasible, construct barriers to stop floodwater from entering the building and seal walls in basements with waterproofing compounds.
Remember these important points when driving in flood conditions:
- 6″ of water will reach the bottom of most passenger cars causing loss of control and possible stalling
- 1′ of water will float many vehicles
- 2′ of rushing water can carry away most vehicles including sport utility vehicles and pick-ups
- Do not attempt to drive through a flooded road. The depth of the water is not always obvious. The roadbed may be washed out under the water and you could be stranded or trapped.
- Barricades are there for your protection – do not drive around them. Turn around and go the opposite direction.
- Do not try and take shortcuts, they may be blocked. Stick to designated evacuation routes.
- Be especially cautious driving at night when it is harder to recognize flood dangers.
DURING A FLOOD
If a flood is likely in your area, you should:
- 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 and do not wait for instructions to move.
- 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.
If you must prepare to evacuate, you should do the following:
- Secure your home – if you have time bring in outdoor furniture and move essential items to an upper floor
- Turn off utilities at the main switches or valves if instructed to do so and disconnect electrical appliances. Do not touch electrical equipment if you are wet or standing in water.
If you have to leave your home, remember these evacuation tips:
- Do not walk through moving water – 6″ of moving water can make you fall
- If you have to walk in water, walk where the water is NOT moving and use a stick to check the firmness of the ground in front of you.
A flood can cause physical hazards and emotional stress. You need to look after yourself and your family as you focus on cleanup and repair.
- Avoid floodwaters – water may be contaminated by oil, gasoline or raw sewage
- Serice 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.
- Rest often and eat well
- Keep a manageable schedule. Make a list and do jobs one at a time.