Flooding can manifest in various forms, depending on the underlying cause or source of water. It's important to remember that heavy rainfall does not necessarily need to be where you are for flooding to occur. It can flood where the rain is and flow into your area. Understanding the different types of flooding is crucial for businesses to effectively prepare for and mitigate their impacts. By gaining insight into these different types of flooding and associated risks, businesses can implement appropriate measures to better protect their people and property.

Riverine Flooding

Riverine flooding happens when rivers or streams overflow due to heavy rainfall, snowmelt, or dam failures. The onset of this type of flooding is often slow and can affect extensive areas along the river's course. To manage riverine flooding effectively, businesses should have an emergency plan. In May 2011, the Mississippi River flooded from record rainfall and snowmelt. The flood was one of the largest and most damaging to occur along the waterway in the last century.

Flash Flooding

Flash floods are rapid and intense floods that occur within a short period, usually under six hours. Heavy rainfall commonly triggers this flooding, particularly in mountainous or urban areas with inadequate or blocked drainage systems. Due to their swift onset, flash floods pose significant dangers and can cause substantial damage. In September 2013, a slow-moving front stalled over Colorado, resulting in heavy rain and catastrophic flooding along Colorado's Front Range. The storm dumped more than 17 inches of rain over an eight-day period, causing the Platte River to reach flood levels higher than ever recorded.

Coastal Flooding

Coastal flooding, tidal flooding, or storm surge arises from high tides, storms, or hurricanes that cause ocean waters to rise and inundate low-lying coastal areas. This flooding can lead to erosion, infrastructure destruction and harm to coastal ecosystems. In October and November 2012, Superstorm Sandy made landfall in southern New Jersey, bringing a tremendous storm surge to New Jersey, New York and Connecticut, leaving parts of the area devastated.

Urban Flooding

Urban areas with extensive pavement and limited natural drainage are susceptible to urban flooding. Heavy rainfall overwhelms stormwater drainage systems, accumulating water on streets, basements and low-lying areas. In September 2021, heavy rain from Hurricane Ida caused major streets in New York City to look more like rivers. Subway stations and tracks became so flooded that service had to be suspended.

Dam or Levee Failure

Flooding can result from the failure or breach of dams or levees designed to hold back water. Excessive rainfall, inadequate maintenance, or structural defects can cause such failures, leading to widespread flooding downstream. For example, on Aug. 29, 2005, more than 50 levees and floodwalls protecting New Orleans, Louisiana, and its suburbs failed after Hurricane Katrina. The failures caused flooding in 80% of New Orleans and St. Bernard Parish. At least 1,400 people died from the levee failure.

What to do when flooding is imminent?

During a flooding event, you should move to the highest point possible. Avoid entering basements, underground parking garages, or storage areas when flooding is imminent. It is never safe to drive or walk through rising waters. A good phrase to remember is turn around, don't drown. AccuWeather For Businesswill send you an alert when flooding is imminent so you, your employees, and your customers can get to higher ground.

Be proactive with AccuWeather's SkyGuard® Warnings, which will deliver site-specific alerts and offer warnings well before severe weather hits, giving you much-needed time to be prepared. Contact us today.

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How heavy rainfall can impact your business and how you can prepare