Quantifying impervious surface changes using time series planimetric data from 1940 to 2011 in four central Iowa cities, U.S.A

Abstract

Rapid expansion of urban areas has been identified as a significant challenge for management of natural systems in and around cities and for their residents. As a starting point, urban expansion must be quantified before it can be associated with other natural or social processes. Although spatial metrics have been used previously to quantify urban expansion, they have only rarely been applied to planimetric data. Using multi-year high-resolution planimetric data, a percent impervious surface-based zoning strategy, and six spatial metrics, we quantified impervious surface (IS) changes in four rapidly growing cities in central Iowa, U.S.A. from 1940 to 2011. We documented increases in IS area over time, primarily due to increases in buildings and parking lot areas in the most recent 20 years. Application of a new spatial metric, percent connected impervious surface area, indicated increasingly connected IS area throughout the period of study. Application of a second new metric, road equivalent width, indicated gradual increases in road width over time. Distinct spatial patterns of change for IS classes occurred in the three different percent IS zones, with roads dominating low percent IS zones, buildings dominating medium percent IS zones, and parking lots dominating high percent IS zones. Use of low impact practices (pervious pavement, bioswales, sand filters) is recommended to minimize impact from expanding and increasingly connected IS areas. Further, land use policies and planning tools could be strategically implemented by targeting specific IS classes that dominate different city zones.