Floods are one of the most common hazards in the United States, however not all floods are alike. Some floods develop slowly, while others such as flash floods, can develop in just a few minutes and without visible signs of rain. Additionally, floods can be local, impacting a neighborhood or community, or very large, affecting entire river basins and multiple states.
Flash floods can occur within a few minutes or hours of excessive rainfall. Flash floods often have a dangerous wall of roaring water carrying rocks, mud and other debris. Overland flooding, the most common type of flooding event typically occurs when waterways such as rivers or streams overflow their banks as a result of rainwater or a possible levee breach and cause flooding in surrounding areas. It can also occur when rainfall or snowmelt exceeds the capacity of underground pipes, or the capacity of streets and drains designed to carry flood water away from urban areas.
Be aware of flood hazards no matter where you live or work. Even very small streams, gullies, creeks, culverts, dry streambeds or low-lying ground that appear harmless in dry weather can flood.
As a result of increased rainfall, hillside property owners' homes may be vulnerable to landslides and mudflows.
California Specific Weather Watches and Warnings - National Oceanic and Atmospheric (NOAA)
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.
California Data Exchange Center (CDEC) - installs, maintains, and operates an extensive hydrologic data collection network including automatic snow reporting gages for the Cooperative Snow Surveys Program and precipitation and river stage sensors for flood forecasting. CDEC provides a centralized location to store and process real-time hydrologic information gathered by various cooperators throughout the State. CDEC then disseminates this information to the cooperators, public and private agencies, and news media.
To Prepare for a flood and increased rainfall, you should:
- Repair roof leaks.
- Fix broken windows and doors.
- Weather-strip doors and windows.
- Have emergency building materials handy for emergency weatherproofing.
- Install rain gutters. If you already have rain gutters, make sure they are free of debris.
- Take erosion control measures on hillsides prone to slipping or mudslides. Properly grade and provide drainage for your yard and garden. Use landscape netting/sandbags/plastic. Sandbags and sand is available at Station 1 (9600 Culver Blvd.; sand is located just outside of the Irving Pl gate).
- As in preparation for all emergencies/disasters, store supplies at work, home and car in sealed waterproof containers.
- Make a plan.
- Buy flood insurance.
If a flood is likely in your area, you should:
- Be aware that flash flooding can occur. If there is any possibility of a flash flood, move immediately to higher ground.
- Do not wait for instructions to move.
- Be aware of streams, drainage channels, canyons, and other areas known to flood suddenly.
- Flash floods can occur in these areas with or without such typical warnings 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. 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. If you have to leave your home, remember these evacuation tips:
- 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. You and the vehicle can be quickly swept away.
The following tips are important to remember when driving in flood conditions:
- Six inches of water will reach the bottom of most passenger cars causing loss of control and possible stalling.
- A foot of water will float many vehicles.
- Two feet of rushing water can carry away most vehicles including sport utility vehicles (SUV’s) and pick-ups.
The following are guidelines for the period following a flood:
- Listen for news reports to learn whether the community’s water supply is safe to drink.
- Avoid floodwaters; water may be contaminated by oil, gasoline, or raw sewage. Water may also be electrically charged from underground or downed power lines.
- Avoid moving water.
- Be aware of areas where floodwaters have receded. Roads may have weakened and could collapse under the weight of a car.
- Stay away from downed power lines, and report them to the power company.
- Return home only when authorities indicate it is safe.
- 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.
- Service damaged septic tanks, cesspools, pits, and leaching systems as soon as possible.
- Damaged sewage systems are serious health hazards.
- Clean and disinfect everything that got wet. Mud left from floodwater can contain sewage and chemicals.
The Centers for Disease Control and Prevention (CDC) has specific information on what steps should be followed when returning to your residence or business after a flood. More information is available by clicking the links below:
- California Department of Water Resources Flood & Safety Topics
- FEMA Flood Information - floods are one of the most common hazards in the United States. Flood effects can be local, impacting a neighborhood or community, or very large, affecting entire river basins and multiple states.
- Ready America - Floods - Provides additional information on flooding which is the nation's most common natural disaster. It's important to be prepared for flooding no matter where you live, but particularly if you are in a low-lying area, near water or downstream from a dam. Even a very small stream or dry creek bed can overflow and create flooding.
- California Hospital Association - Flood Preparedness for hospitals is discussed by the CHA.
For information on protecting or mitigating potential flood damage, please refer to the links below: