World Congress of Soil Science Logo 18th World Congress of Soil Science
July 9-15, 2006 - Philadelphia, Pennsylvania, USA
International Union of Soil Sciences

Friday, 14 July 2006

This presentation is part of 111: 3.1A Land Use Planning: Environmental, Economic and Social Trade-offs - Oral

Using GIS Tools to Identify Valuable Soils, Viable Farms and Vulnerable Areas.

Caroline M. Alves, USDA /NRCS, 1193 South Brownell Rd., Suite 35, Williston, VT 05495

The loss of the highest quality agricultural land to urban sprawl is occurring at an accelerating pace throughout the United States. In New England, a rapidly appreciating real estate market, coupled with a housing shortage has put intense pressure on developing the remaining open land. Digital soils data is now available in a variety of formats to those in the land-use planning community. Yet, to what degree are planners incorporating soil considerations in locating where development occurs? The availability of digital data often outstrips the ability of planning officials to integrate this information with decisions occurring on the ground. There is a critical need to find innovative ways to assess how much agricultural land is being lost, in a timely and locally relevant framework. GIS technology can help planners to visualize alternative patterns of development that will minimize further fragmentation of farmland. The volatility in energy prices accentuates the need to maintain open land for a more locally based agricultural production system in the near term and for future generations. The focus of the study is Lewis Creek watershed in north-western Vermont. It covers an area a 52,000 acres in extent. The area is predominantly rural yet threatened by urban encroachment. It is a working landscape with farms, woodlands and residences intermixed. Vermont has an unusually high population/sprawl ratio, meaning land is being developed at a faster rate than the population is growing. There is an urgent need to examine the general trends of the spread of rural residential development at a resolution that reveals the true extent of land use transitions. Areas like Lewis Creek watershed have a dispersed population and land use decisions are primarily made at the town level, on a permit by permit basis. It is often difficult to foresee the full impact of incremental development over time. Town officials need to be conversant with the practical implications of technical soils data and then be able to put this information into a wider context. Until recently, the main emphasis of the Cooperative Soil Survey Program has been on data creation and automation with less attention on helping users understand the data. The main objective of this paper is to demonstrate a combination of visual and quantitative GIS-based techniques to assist planners in preserving the best agricultural soils. A map of the watershed showing Important Farmlands derived solely from soils data does not give a realistic assessment of the remaining agricultural land resource. Instead, it is necessary to include current land use data in the analysis to determine which areas of high quality soils are still in active agricultural use. Utilizing e911 point data for house locations offers a yearly snapshot of where development is spreading most rapidly. Moreover, house location data is used in a predictive model to quantify potential factors that influence development in the Lewis Creek watershed. This helps to pinpoint which areas are most vulnerable to development. Additionally, to target farmland preservation efforts to the most viable farms, patch metrics are employed to characterise the largest areas of contiguous farmland. Local planners need concrete examples of how to integrate and analyze the multitude of data sources to better understand growth patterns as they are occurring. This will enable them to evaluate the consumption of agricultural land by piecemeal development and find new strategies to retain productive farmland.

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