Understanding The Types And Causes Of Floods

Different Types Of Floods

While Gene Kelly, American dancer, choreographer, actor, and singer found happiness singing in the rain, the National Weather Service better understands nature’s fury, as exhibited by such weather conditions as tropical cyclones, low-pressure systems, thunderstorms, snow-melt, and debris flows, are the cause for the following four types of floods that can wreak havoc to NYC residences and businesses:

Flash Flooding: Flash flooding occurs within 6 hours of rain intensity from a severe thunderstorm, hurricane, tropical storm, or the rare event of a dam breaking or a mudslide. Residents of urban areas, such as New York City,  are more likely to experience flash flooding. In the ‘asphalt jungle,’ as cities are sometimes described, there is less soil to absorb the rainfall, allowing rain to run to the low-lying streets, parking lots, driveways, and basements. The danger of a flash flood can also occur because of arid soil due to a lack of rainfall. The rain intensity is so quick that the soil can’t absorb the water fast enough, leading to rain running off to lower areas such as a home or business basement. Flash flooding is the cause of structural foundation damage, damage to home appliances, and the devastation to walls, floors, and furnishings due to mold growth.

Coastal Flooding: Coastal flooding is caused by the water surging onto the land due to high tides and higher than normal ocean waves. The island of Manhattan, as well as Long Island, are always at risk for coastal flooding, as well as Florida, California, Louisiana, and New Jersey. The consequences of coastal flooding are drownings, as well as illness due to contaminated water, injuries that result from the haste to escape the rising water and falling debris, and respiratory conditions from the excessive damp conditions that bring mold growth. Coastal flooding can bring minor, moderate, or major damage. Moderate coastal flooding has the ‘possibility’ of being life-threatening. Major coastal flooding is life-threatening and evacuation orders need to be obeyed!

River Flooding: Never underestimate the flowing waters of a river or stream! Any size river or stream has the potential of overflowing its riverbanks. River flooding results from heavy and long-lasting thunderstorms, snow melt, or ice jams, causing the waters to run over its banks and flood the surrounding neighborhood. While river flooding can cause property damage, most flooding is predictable, providing enough time for safe evacuation. Significant property damage is unlikely, except for instances of a break in a dam or dike.

Groundwater Flooding: Groundwater flooding occurs in urban, suburban, and rural settings. The cause is the drainage system (sewer system) becoming inundated by a steady and significant rainfall, with the excess water overflowing the grates of the drainage system onto the streets and properties. Groundwater floods are gradual, but such flooding lingers until the standing and stagnant water is absorbed into the soil or can run back to the drainage system after the rainfall. Groundwater flooding has the potential to cause structural damage to residential or business properties, as well as bring about the growth of mold or mildew.