Wildland Firefighting Practice Exam

If the slope doubles, what happens to the rate of spread?

1. It remains the same

2. It triples

3. It quadruples

4. It doubles

The correct answer is: It quadruples

When considering the relationship between slope and the rate of spread of a wildfire, it's important to understand how fire behavior is influenced by the terrain. As the slope increases, the rate of spread typically increases due to the gravitational pull aiding the fire's movement upward. In practical terms, if the slope doubles, research and fire behavior models indicate that the rate of spread can significantly increase—often observed as quadratic or exponential growth in relation to slope changes. This means that when the slope is doubled, the impact on speed is more pronounced than a simple linear increase. The reason for this is that steeper slopes create a greater intensity of fire behavior due to enhanced convection and preheating of fuels above the fire's active edge. Thus, we observe that when the slope doubles, the resulting effect on the fire's rate of spread leads to an increase that could be described as quadrupling the fire's rate of spread, reflecting the more aggressive nature of fire on steeper terrain. This understanding demonstrates the critical importance of topographical features in managing and predicting fire behavior during wildland firefighting efforts.