Tuesday, November 8, 2011

Green Roofs - many times the last line of defense for water quality

Green and living roofs are so very important to our water quality, sometimes being the last line of defense for removing pollutants before runoff enters our waterways.

Green roofs slow down stormwater, cleaning and sequestering pollutants 
Even small green roofs can provide a significant benefit to reducing peak runoff amounts and reducing loadings on creeks, rivers and ponds.
Blue Hole, Ichetucknee Springs
Once stormwater hits a roof and flows to the street below it may only be a matter of minutes before the water and any contaminants picked up as the volume flows across streets, drives and roads enters Florida's drinking water supply.

Floating wetlands, Gainesville, Florida - greenroof on a pond
Storm drain allows pollutants to enter waterways
Florida has a unique geology across many parts of the state called Karst.  Karst formations are typified by limerock with caves, tunnels and holes throughout the  formation.  Once stormwater runoff enters the limerock above drinking aquifers the flow to the pools of underground water can be very quick.

Many times storm drains are a direct connect to water supply aquifers
Green roofs, living walls, floating wetlands and other best management practices can help keep water clean by slowing the runoff and removing contaminants from the water.

Wekiwa Springs, Florida - higher in nitrogen and algae
 Wekiwa Springs, located just north of Orlando, Florida and shown above is surrounded by houses, streets, roads and commercial development.  Though many good best management practices are in place to contain nutrients and runoff, the springs still suffer from high nutrient contents such as nitrogen and phosphorous.
Salt Springs, Ocala National Forest, not as impacted by development
Salt Springs in the Ocala National Forest on the other hand, though threatened by development, does not have all the septic tanks, stormwater runoff and as you can see, the water is much clearer, contains less nitrogen and other nutrients and is so much more healthy.

Installing a green roof on your commercial or residential building is just one small contribution you can make int he Urban Core to help protect water supplies.

1 comment:

Lavenia Mannan said...

Yeah, plants are very good natural "cleaners." That's why it is good to have trees on sidewalks. These serve the same function as green gardens on our roof. You just need to clean your surroundings of dried leaves.