An assessment of impervious surface areas in Rhode Island

Abstract

Impervious surface area (ISA) has emerged as a key indicator to explain and predict ecosystem health in relationship to watershed development. In this study, we extracted the information of ISA for the state of Rhode Island using 1-m spatial resolution true-color digital orthophotography data. We employed an object-oriented algorithm of multiple-agent segmentation and classification (MASC) that we developed for ISA information extraction. The result indicates that, as of 2004, 10% of the state land has been covered by ISA. The major population centers and historical cities, such as Providence, Woonsocket, and Newport, have ISA over 30%. The heavily settled suburban communities have ISA between 10 and 30%. Only 17 out of 39 towns in the state have less than 10% ISA. The average ISA for the coastal towns is 14%. Because most stream-quality indicators are predicted to decline when watershed ISA exceeds 10%, the results from this study serve as an alarming indicator for managing the state's watershed and coastal ecosystems. The tested MASC model could be extended to coastal Massachusetts and Connecticut to provide a more comprehensive indication of the impacts of human-induced land-cover change on southern New England's coast.