What impact does replacing natural vegetation with impervious surfaces have on water quality?

Replacing natural vegetation with impervious surfaces significantly affects water quality primarily by increasing the volume and velocity of stormwater runoff. Natural vegetation plays a crucial role in absorbing rainfall, reducing runoff, and filtering pollutants through the soil. When impervious surfaces, such as roads and parking lots, are introduced, rainwater cannot be absorbed into the ground. Instead, it flows quickly over these surfaces, carrying with it pollutants like oil, heavy metals, sediments, and nutrients directly into nearby waterways without any natural filtration.

The increased volume and rapid movement of stormwater also lead to higher peak flows in streams and rivers, which can cause erosion, habitat destruction, and the destabilization of stream banks. This rapid runoff can lead to greater amounts of pollutants being washed into the water, exacerbating issues like algal blooms and reducing overall water quality. Thus, the replacement of natural vegetation with impervious surfaces is directly linked to negative impacts on water quality through increased runoff and subsequent pollution.