Land cover along an urban-rural gradient: Implications for water quality

Development pressures in rural mountainous areas of the United States hold crucial implications for water quality. Especially important are changes in the extent and pattern of various land uses. We examine how position along an urban-rural gradient affects landscape patterns in a southern Appalachian watershed, first by testing for the effect of distance from an urban center on land-cover change probabilities and then simulating the implied development of a landscape at regular distance intervals. By simulating a common hypothetical landscape we control for variable landscape conditions and define how land development might proceed in the future. Results indicate that position along the urban-rural gradient has a significant effect on land-cover changes on private lands but not on public lands, Furthermore, position along the gradient has a compounding effect on land-cover changes through interactions with other variables such as slope. Simulation results indicate that these differences in land-cover changes would give rise to unique "landscape signatures" along the urban-rural gradient. By examining a development sequence, we identify patterns of change that may be most significant for water quality. Two locations along the urban-rural gradient may hold disproportionate influence over water quality in the future: (1) at the most remote portion of the landscape and (2) at the outer envelope of urban expansion. These findings demonstrate how landscape simulation approaches can be used to identify where and how land use decisions may have critical influence over environmental quality, thereby focusing both future research and monitoring efforts and watershed protection measures.