Parking lots can contribute to water pollution when rain carries oil & sediments
The U.S. Geological Survey (USGS) released a model in May 2019 that uses data to estimate the amount of land covered by impervious parking lots. These findings may be helpful to watershed managers as they plan new developments or areas where runoff pollution is an issue, according to USGS.
According to Water Environment Federation, the most impervious spaces include industrial and military facilities, and major transportation centers. Commercial land has had the highest percentage of parking lot coverage in the last four decades, according to data. Parking lots can contribute to water pollution when rain carries oil, tire sediments, and metals into waterways from storm water runoff. This data can help infrastructure and water quality planners decide on retrofits and interventions, according to USGS.
In 2018, there were approximately 275 million registered motor vehicles in the U.S. According to the WEF, all those vehicles cover a large amount of parking lot coverage, which is made of pavement that storm water cannot filtrate.
The USGS team used data from six cities–Bloomington, Ind.,; Chattanooga, Tenn.; Denver, Colo.; Hartford, Conn.; Raleigh, N.C.; and St. Paul, Minn.–to calculate the parking lot coverage of land use.
The data also gave researchers a way to test and see if their model aligns with actual parking lot coverage, according to WEF. Most estimates were within 1% of coverage figures. However, the estimate for Hartford, Conn. was inaccurate for about 5%. The estimates are useful for modeling large areas such as cities and watersheds, however it is less useful for data in study areas smaller than 80 km2.
USGS’ datasets for parking lot coverage in the last 50 years can be viewed here.