Investigating the substantive effectiveness of Strategic Environmental Assessment of urban planning: Evidence from Italy and Spain

We investigated the substantive effectiveness of Strategic Environmental Assessment (SEA) of urban planning in Italy and Spain, by looking at the changes made to the original plan as a result of the SEA process. The Italian and Spanish SEA legislations establish an SEA Authority, different from the one that elaborates the plan and the Environmental Report. This authority is in charge of supervising the SEA process and issuing a final statement containing directions and prescriptions on environmental issues to be implemented in the plan as a prerequisite for its approval. After having reviewed a sample of SEA in these two countries, we found that in the great majority of cases the SEA authority required some changes, despite the fact that the plans had undergone an environmental assessment. Results also indicate that the legal arrangements, and in particular the level of independence of the SEA authority (which in Italy and Spain is determined at the regional level), affect the quality and quantity of requested changes. In regions where the SEA Authority is established at a higher level in the planning hierarchy, more substantial changes tended to be required, including more mitigation and compensation measures. On the contrary, in regions where a subsidiary approach is in place, i.e. the SEA authority is established within the same municipality that elaborates the plan, less substantial modifications are more often required. We conclude that in the Spanish and Italian contexts a more effective SEA, in terms of environmental performance of urban plans, is supported by institutional arrangements that provide for an SEA Authority clearly separated and fully independent from the planning Authority.