Land-cover change model validation by an ROC method for the Ipswich watershed, Massachusetts, USA

Scientists need a better and larger set of tools to validate land-use chang e models, because it is essential to know a model's prediction accuracy. Th is paper describes how to use the relative operating characteristic (ROC) a s a quantitative measurement to validate a land-cover change model. Typical ly, a crucial component of a spatially explicit simulation model of land-co ver change is a map of suitability for land-cover change, for example a map of probability of deforestation. The model usually selects locations for n ew land-cover change at locations that have relatively high suitability. Th e ROC can compare a map of actual change to maps of modeled suitability for land-cover change. ROC is a summary statistic derived from several two-by- two contingency tables, where each contingency table corresponds to a diffe rent simulated scenario of future land-cover change. The categories in each contingency table are actual change and actual non-change versus simulated change and simulated non-change. This paper applies the theoretical concep ts to a model of deforestation in the Ipswich watershed, USA. (C) 2001 Else vier Science B.V. All rights reserved.