Impervious surface cover is commonly used as an environmental indicator for land use and watershed planning. The net quantity of impervious surface added per quantity of residential and commercial development, including the added impervious surface at the development site as well as the offsite impacts associated with the development (e.g., roads and other infrastructure), can serve as a partial measure of the net impacts of site development.
Net impervious surface growth rates can be compared as a partial surrogate for predicting the relative impacts of alternative land development proposals on water quality, flood control infrastructure, stream erosion, groundwater recharge, and habitat. While a variety of approaches are currently used to estimate impervious cover, these approaches are limited in several ways for comparing alternative land use scenarios.
The impervious surface growth model was developed to overcome those limitations and fill unmet needs. It can predict the net increase in impervious cover at the census block group scale as a function of quantities of residential and commercial development added and relative centrality of the block group in a metropolitan region. This tool has potential for applications to planning and policy development, as well as watershed and drainage planning.
A Place-Based Tool for Assessing Cumulative Impervious Surface Outcomes of Proposed Development Scenarios (2012) presents the process used to develop the impervious surface growth model, evaluates the model's reliability, and discusses applications and potential future enhancements.You may need a PDF reader to view some of the files on this page. See EPA’s About PDF page to learn more.