What effect does increased impervious surfaces have on runoff in flood-prone areas?

In flood-prone areas, increased impervious surfaces significantly contribute to runoff. When surfaces such as roads, buildings, and parking lots become impervious, water is unable to infiltrate into the ground, leading to a higher volume of surface runoff. This increased flow quickly enters drainage systems and waterways, resulting in elevated flood levels during periods of heavy rain or storms.

The presence of impervious surfaces disrupts the natural hydrological cycle, where water would typically seep into the ground and be absorbed by vegetation. Instead, the excess water rapidly flows into streams and rivers, often overwhelming the existing capacities of drainage systems and increasing the likelihood and severity of flooding. Hence, the correct answer highlights the direct relationship between increased impervious surfaces and the resulting higher flood levels due to enhanced runoff.