Resource information
Mapping urban expansion and impervious surfaces (IS) has become a useful tool for supporting watershed assessments. The lack of large-area time-series maps created the need to develop an approach and products that can easily be scaled. In this research application, 81 Landsat 1, 2, and 5 scenes for the epochs of 1975, 1985, and 1996 were used to map urban land use/land cover across New England, USA. A Classification And Regression Tree (CART) using random forest classified the landscape into a scheme matching the 2011 National Land Cover Database scheme, which was then aggregated to urban versus nonurban land cover. Regression models between Tasseled Cap brightness and greenness indices and IS values were developed. The CART and IS models were applied to modern imagery and backcast to selected archived imagery to generate maps of urban and IS across New England for the past four decades. The aggregated urban versus nonurban maps had an overall accuracy of 95% and the IS model had an R ² of 0.89. Multiscale spatiotemporal analyses show the highest urban expansion in watersheds along the coasts in southeastern New England and along highway corridors. Imperviousness intensity increase of urban existing in 1975 was highest for the coastal northeast between 1975 and 2011. The products will be used to support lake risk management and help identify potential stressors to lake health in the northeast.
