Floods occur due to various natural and human-induced factors:
1. **Heavy Rainfall**: Excessive rainfall over a short period can overwhelm rivers and drainage systems, leading to flooding.
2. **River Overflow**: Rivers can overflow their banks due to prolonged rain or melting snow, causing nearby areas to flood.
3. **Storm Surges**: Coastal areas can experience flooding from storm surges during cyclones or hurricanes, where high winds push seawater inland.
4. **Snowmelt**: Rapid melting of snow and ice can increase river flows, leading to floods downstream.
5. **Tsunamis**: Coastal regions may experience flooding from tsunamis triggered by underwater earthquakes or volcanic eruptions.
6. **Poor Drainage**: Urbanization and inadequate drainage systems can prevent water from flowing away efficiently, resulting in localized flooding.
7. **Deforestation**: Loss of vegetation can reduce the land's ability to absorb rainfall, increasing runoff and flood risk.
8. **Land Use Changes**: Construction and development can alter natural water flow patterns, increasing the likelihood of flooding in some areas.
These factors can act individually or in combination to create flood conditions.