Floods can be caused by a variety of factors, often acting in combination. Here are some of the most common causes:

• Heavy Rainfall: Excessive rainfall over a short period can overwhelm drainage systems and lead to flash floods. ready.gov
• River Overflow: When rivers receive more water than their channels can hold, they overflow onto adjacent floodplains. USGS
• Coastal Flooding: Storm surges from hurricanes or other coastal storms can cause significant flooding in coastal areas. High tides can also exacerbate the problem. NOAA
• Dam Failure: If a dam fails, the sudden release of a large volume of water can cause catastrophic flooding downstream. FEMA
• Snowmelt: Rapid snowmelt, especially when combined with rainfall, can lead to increased river flow and flooding. National Weather Service
• Deforestation: Trees and vegetation help absorb rainfall and slow runoff. Deforestation can increase the risk of flooding. WWF
• Urbanization: Urban areas often have extensive paved surfaces that prevent water from soaking into the ground, increasing runoff and flood risk. American Rivers
• Climate Change: Climate change is contributing to more extreme weather events, including heavier rainfall and more intense storms, which can increase the frequency and severity of floods. EPA