Tree Canopy’s Evil Twin
Most watersheds in Georgia were originally forested. Over time these lands were first cleared for agriculture, some returned to forests and others were and are being developed. Development includes not just the buildings, but the roads, sidewalks, parking and other paved surfaces associated with urban infrastructure. This impervious surface is the counter to the tree canopy that represents existing green space.
Impervious surfaces prohibit infiltration of precipitation and increases runoff. The increase of impervious surfaces in a watershed impacts the streams hydrologic, physical, biological characteristics, as well as water quality. Minimizing impervious surface or making sure that it is disconnected from any receiving water body can help to reduce these impacts. However, it is often most cost effective to either protect or enhance existing forests to maintain water quality. Once again these are considerations that must be taken into account when creating a green infrastructure plan.