Residential Impervious Surface Analysis

The Village of Morton Grove, IL has a regulation in place that allows the Village to govern impervious surfaces, which accounts for everything that is not grass, for residential rear yards, with only 50% coverage being the regulated limitation.  The village Zoning Administrator requested that the village’s Geographic Information Systems (GIS) department assist them with understanding the existing total impervious surface coverage for all parcels in the residential zoning districts.  The Department of Community and Economic Development would like to use this information to better understand the amount of residential impervious surfaces village wide and to use this information to craft regulations, public notices, and gain a better understanding of land use in the community.

Currently, the village does not require residents to record the type and amount of impervious surface in the rear yard of a property. To help determine what type and how much impervious surface exists, the GIS staff leveraged the existing buildings, driveway, and sidewalk data layers that exist for the village to determine what was present on each residential parcel. This provided a good base for an average impervious surface percentage to be calculated. The total area of buildings, driveways, and sidewalks per residential parcel was calculated and divided by the total area of the residential parcels to yield the percentage of impervious surface.

By leveraging existing GIS data to calculate this information, the village Zoning Administrator was able to get an approximate percentage of impervious surface per parcel in all residential zoning districts.  Without GIS, this type of analysis would have been very time consuming and most likely would have involved paying for a costly survey of the village.