The correct answer is: d) River valleys.
Flash floods are a particular risk in river valleys because they are low-lying areas that are often close to rivers. When heavy rains fall, the water can quickly flow down the river and cause flooding. This can be a serious problem, as it can damage property, injure people, and even kill people.
High altitude regions are not as prone to flash floods because the water has more time to soak into the ground. Densely forested regions are also less prone to flash floods because the trees help to absorb the water. Urban areas with poor drainage are more prone to flash floods because the water has nowhere to go but to flow over the surface.
Here are some additional details about each option:
- High altitude regions: The air is thinner at high altitudes, which means that there is less water vapor in the air. This makes it less likely that there will be heavy rains, which can cause flash floods.
- Densely forested regions: Trees help to absorb water, which means that there is less water that can flow over the surface and cause flash floods.
- Urban areas with poor drainage: When it rains, the water in urban areas often flows over the surface because there is not enough drainage infrastructure to handle the amount of water. This can cause flash floods.
- River valleys: River valleys are low-lying areas that are often close to rivers. When heavy rains fall, the water can quickly flow down the river and cause flooding. This can be a serious problem, as it can damage property, injure people, and even kill people.