In conclusion, we discuss how effectively the ISGM addresses requirements laid out at the beginning of this paper.
We believe the ISGM represents a significant advancement in meeting the unmet scenario analysis needs described earlier in this paper.
The ISGM supports scenario analysis throughout the contiguous United States.
The ISGM returns an estimate of the net impervious surface growth per change in units of housing units and employees.
The ISGM input parameters include development density (housing units per unprotected acre and employees per unprotected acre) and jobs within a 30-mile radius (an indicator regional centrality).
The ISGM implicitly accounts for off-site impervious surface growth (e.
The ISGM interface has been developed to provide simple access to the ISGM and allow a large number of scenarios to be processed efficiently.
Although limitations have been identified, the ISGM generally is considered to provide reliable estimates of net impervious surface growth to support planning-level scenario analysis across a wide range of urban, suburban, and rural conditions.
While more detailed site-specific analysis would always be required to fully understand the impacts of a proposed development project, the ISGM has the potential to allow users to quickly and roughly compare the estimated impervious surface impacts of a number of proposed development sites.
The ISGM has the potential to allow urban planners and policy makers to conduct rapid planning level analysis of the relative water quality impacts of various development and land-use scenarios.
Given the importance of impervious cover in storm-water planning, a variety of other potential uses may exist for the ISGM or the underlying regression model.
A number of potential enhancements currently are under consideration to improve the ISGM.