Addressing cumulative effects in Strategic Environmental Assessment of spatial planning

Strategic environmental Assessment (SEA) is a decision support instrument for predicting and evaluating the likely environmental effects of implementing a policy, plan or programme. SEA can consider the cumulative impacts of more than one project or activity on the same environmental component. This paper discusses the analysis of cumulative effects in SEA, with reference to spatial planning by: providing a review of key concepts and methods related to cumulative effects literature; presenting a rationale for the inclusion of cumulative effects in SEA of spatial plans; advancing a proposal to address cumulative effects in different SEA stages. The paper concludes that SEA offers the opportunity to support a better management of cumulative effects arising from many local-level spatial planning decisions. Three aspects emerged as critical to ensure good practices: the selection of valued environmental components, the adoption of future-oriented approaches, and the use of spatially-explicit information.