Using Participatory GIS to Improve Community Land Use Decisions: A Demonstration Using TVAL-Farm

Background

This research presents the Farmland Values Project¹'s TVAL-Farm tool which incorporates scenic quality and cultural heritage elements to create an enhanced Land Evaluation and Site Assessment (LESA) model. The LESA model, developed by the United States Department of Agriculture Natural Resource Conservation Service (NRCS), has been used across the country as a decision making resource particularly in the context of farmland preservation programs. This project develops a method for enhancing LESA's Site Assessment Factor 3 (SA-3), factors measuring “Other Public Values”. The enhancement of the LESA model provides insight and a framework on how to collect and incorporate qualitative public values data within the quantitative environment of a Geographic Information System (GIS). This information is not typically included in farmland preservation benefit estimates and thus represents a significant bridge between the qualitative and quantitative studies of the importance of farmland to rural areas.

LESA is a numeric rating system created by the NRCS to evaluate a parcel's relative agricultural importance. The land evaluation (LE) component of a LESA system measures soil quality (Pease and Coughlin 1996). It is usually based on land capability classes, important farmland classes, soil productivity ratings and/or soil potential ratings (Pease and Coughlin 1996). The site assessment (SA) component evaluates other factors that contribute to the site's agricultural importance such as parcel size and on-farm investments. SA factors may also consider indicators of development pressure such as distance to sewer and water infrastructure and public amenities like wildlife habitat or scenic views (Pease and Coughlin 1996). LESA systems assign points and a relative weight to each of the LE and SA factors. The sum of the weighted ratings is the LESA score; the higher the LESA score, the more significant the site for agriculture. States and localities often adapt the federal LESA system to meet their needs. Once a local system is approved by NRCS, it supersedes the federal system: NRCS is required to use the local version to review federal projects (Pease et al 1994, p.62).

Our enhancements focused on two benefits, scenic quality and cultural heritage significance, derived from survey information gathered in a community mapping activity conducted as part of the Farmland Values Project. Following the methodology of LESA, we assigned weights to each benefit category in order to derive the holistic benefit valuation score. Alternative weighting measures may also be calculated based on public input from various stakeholder groups. The primary product of this research is an enhanced geospatial database and assessment tool that includes qualitative layers for several types of farmland benefits; we call it the Total Value Assessment Tool for Farmland (TVAL-Farm).