This dissertation explores the strengths and weaknesses of Participatory Geographic Information System (PGIS) approaches to Environmental Impact Assessment (EIA) with a specific focus on the potential contribution of Geo-visualization (GVIS) in this process. The approach draws heavily on concepts developed under the broad umbrella of GIS and Society and Critical GIS. PGIS recognizes the political economy of GIS in terms of data access, data representation, structural knowledge distortion, and community empowerment as being legitimate and significant issues in the application of GIS in community projects. EIA has been adopted as one of several important environmental practices that seek to engage the public in decisions made about development projects and to protect community interests in the development process. However, almost no linkage has been made between PGIS and EIA, or the potential for what appears to be a powerful symbiotic relationship. PGIS concepts are especially important in EIA because most large development projects involve complex social and environmental interactions and invariably impact community interests in the localities in which such projects are planned. Exploring the linkage of PGIS and EIA has the potential for a more informed decision-making process, the ability to empower communities in that decision-making, and contribute toward democratic environmental decision-making.

In the EIA process experts make extensive use of tables, matrices, plans, networks, and maps to represent current and possible future environmental conditions should a project proceed. Community participation is an important component of EIA and yet communities experience difficulties in understanding the complex interplay of social, economic, physical, cultural, ecological, and analysis and in contributing to the expertised formal procedures of the EIA process. This technical dominance can lead to the unintended outcome that community participants feeling confused, excluded, and disempowered. However, recent developments in GIS and GVIS, along with the conceptual framework provided by PGIS, provides both a process and a series of techniques by which participants may contribute more meaningfully to an EIA and by which the results of an EIA can be made more understandable and communicated to a broader community audience. Drawing heavily on GIS and GVIS, this dissertation examines the Corridor H project to assess the extent to which current EIA procedures facilitated or inhibited community participation in the decision-making process; whether local communities had useful access to project data; whether communities were able to fully contribute their own local knowledge to the repository of expert environmental and social data; if communities felt that the current Corridor H EIA represented a reasonable representation of social and environmental issues in the locality; and finally the extent to which GVIS methods and techniques empowered local communities to more fully comprehend, contribute to, and influence the EIA process. A PGIS-GVIS approach provides a fascinating case study and insight into community involvement in environmental decision making processes and provides opportunities for communities to be empowered in the course of project development activities.