Assessing the influence of environmental impact assessments on science and policy: An analysis of the Three Gorges Project

The need to understand and minimize negative environmental outcomes associated with large dams has both contributed to and benefited from the introduction and subsequent improvements in the Environmental Impact Assessment (EIA) process. However, several limitations in the EIA process remain, including those associated with the uncertainty and significance of impact projections. These limitations are directly related to the feedback between science and policy, with information gaps in scientific understanding discovered through the EIA process contributing valuable recommendations on critical focus areas for prioritizing and funding research within the fields of ecological conservation and river engineering. This paper presents an analysis of the EIA process for the Three Gorges Project (TGP) in China as a case study for evaluating this feedback between the EIA and science and policy. For one of the best-studied public development projects in the world, this paper presents an investigation into whether patterns exist between the scientific interest (via number of publications) in environmental impacts and (a) the identification of impacts as uncertain or priority by the EIA, (b) decisions or political events associated with the dam, and (c) impact type. This analysis includes the compilation of literature on TGP, characterization of ecosystem interactions and responses to TGP through a hierarchy of impacts, coding of EIA impacts as "uncertain" impacts that require additional study and "priority" impacts that have particularly high significance, mapping of an event chronology to relate policies, institutional changes, and decisions about TGP as "events" that could influence the focus and intensity of scientific investigation, and analysis of the number of publications by impact type and order within the impact hierarchy. From these analyses, it appears that the availability and consistency of scientific information limit the accuracy of environmental impact projections. These analyses also suggest a lack of direct feedback between the EIA process and emerging science, as indicated by the failure of literature to focus on issues related to the design and management of TGP, ultimately challenging the environmental sustainability of the project. While the EIA process has enormous potential for improving both the basic sciences and the planning and sustainability of hydrodevelopment, important institutional changes need to occur for this potential to be realized. This paper concludes with recommendations about those institutional changes needed to improve the feedback between the science and policy, and ultimately the environmental sustainability, of large dams.