Final answer:
The nation's three most flash flood-prone regions include the Southern United States, parts of South Asia (coastal Bangladesh and eastern India), and the Western United States (Pacific Coastal Ranges).
Step-by-step explanation:
The nation's three most flash flood-prone regions are:
- The Southern United States, particularly areas like the Gulf Coast, which are susceptible to heavy rains and storms.
- Parts of South Asia, especially the coastal regions of Bangladesh and eastern India that receive significant rainfall during the monsoon season, leading to severe flooding.
- Western United States, including regions in the Pacific Coastal Ranges where heavy rainfall can lead to landslides and debris flow, both contributing to flash flooding.
Additionally, urbanization has led to increased flash flood risk in cities within these regions due to reduced natural absorption of rainfall by the ground.