Mapping & Monitoring
Impervious Surfaces of the Buzzards Bay Watershed
The Buzzards Bay watershed has seen dramatic growth in the past two decades. Like SE Massachusetts in general, this area is experiencing development pressure from the surrounding heavily populated regions of Cape Cod, metropolitan Boston and Providence. Impervious surfaces are an important variable to track within a watershed ecosystem. They prevent water infiltration and wash surface contaminants into water bodies. In general, the higher the percentage of impervious surfaces the lower water quality. Also impervious surfaces contribute to localized flooding, cause “flashiness” in streams and rivers (frequent and rapid short term changes in streamflow), and prevent recharge of ground water supplies.
In this continuation of the Center’s work identifying the impervious areas of Cape Cod, a 'before and after' snapshot of this landcover type for the entire Buzzards Bay watershed has been completed. To create estimates of impervious surfaces, a standard decision-tree classification method with Landsat satellite imagery was utilized. To get the before and after information, two image dates - 10/28/1985 and 11/22/2002 - used. Both scenes are leaf-off (winter) dates and have been radiometrically rectified to one another; that is, a time tested method to reduce the environmental/atmospheric differences between the two scene dates was used.
The ultimate goal of this research was to produce a spatially explicit digital database of the impervious surfaces of the entire Buzzards Bay watershed of Massachusetts. The WHRC’s satellite image classification model was trained with high quality spatial data from a few city GIS systems that are within the watershed.
Impervious surfaces and subwatershed boundaries for Buzzards Bay watershed 1985 (click image for larger version).
Impervious Surfaces and subwatershed boundaries for Buzzards Bay watershed 2002 (click image for larger version).
To view these data select the links below. You must have Google Earth installed on your machine to make use of these links:
1985 percent Impervious Surfaces by subwatershed
2002 percent Impervious Surfaces by subwatershed
This project was funded by the Coalition for Buzzards Bay.
