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 environmen- tal 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.