- Troy, Austin
UVM, Rubinstein School of Environment and Natural Resources & Aiken Center
While urban development is by definition detrimental to the natural environment, land must be developed to house people and provide places of employment and recreation. “Urban sprawl” is a term used to describe an inefficient pattern of development where the impacts are high relative to services provided. Various authors have attempted to define indicators of sprawl in terms of its social and economic impacts, but few have attempted to operationalize indicators of sprawl related to environmental impact. One of the challenges to this is that what defines sprawl environmentally will vary by ecosystem. The purpose of this project was to develop environmentally functional and spatially-explicit indicators of suburban and ex-urban sprawl that are specific to the Northeastern Forests and that considered per capita impacts. Using existing empirical research, in combination with extensive mapping and spatial analysis efforts, these indicators were used to track the environmental impact of development relative to the number of people housed and employed. Hence, while areas of dense development result in a high impact, their per capita impact is actually low. On the other end of the spectrum, extremely sparse, rural development also has a minimal impact, even on a per capita basis. However, in between those extreme, impact per capita increases. This study attempted to understand the nature of that impact curve (see figure 1) and where certain development patterns fall along that curve. This was done through a synthesis of studies of the impacts of urban development on environmental indicators (habitat fragmentation, biodiversity and water quality) within the Northeastern context. Based on this resulting information, we created two maps for Chittenden County, Vermont. The first was descriptive, showing per capita impact and where densities and arrangements are most and least efficient, based on weightings of population density, soils, topography, hydrography and natural communities. A number of different weighting schemes and threshold values were tried and the resulting maps compared. The second map was prescriptive, showing what level of density that should be required to offset the environmental impacts of conversion at each undeveloped location. It accounted for the fact that certain conversions (e.g. intensive agriculture to subdivision) are less harmful than others (e.g. unfragmented forest to subdivision). These areas were then compared to the prescriptive planning districts from the 2006 Chittenden County Regional Plan.