Numerical evaluation of incremental visual impact

Since the introduction of the Council Directive 85/337/EEC in EU, the Environmental Impact Assessment (EIA) has become a required tool to predict and evaluate a wide range of effects on the environment arising from public and private projects. Landscape and Visual Impact Assessment (LVIA) is a separate but closely linked process that operates within the overall framework of EIA. It specifically aims to ensure that all possible effects of change, both on the landscape and on the visual perception of potential observers, are taken into account in decision-making. The Visual Impact Assessment (VIA), in particular, is concerned with how individuals or groups of people may be specifically affected by a change in the landscape’s visual perception. This means assessing changes in specific views and in the general visual amenity experienced by particular people in particular places. The visual impact assessment typically includes the preliminary identification of the viewpoints from which the landscape modification is actually visible and the successive estimation of the visual effect based on direct or indirect criteria. The article deals with the application of a quantitative assessment procedure, which integrates the preliminary identification of the viewpoints from which the modification is visible by means of the Intervisibility Analysis (IA) and the subsequent calculation of the Level of visual impact (Lvi) for each of the selected viewpoints. The article discusses the application of the proposed assessment procedure to the expansion of an existing BRDA (Bauxite Residue Disposal Area) located in south-west of Sardinia, for which the EIA procedure requires the evaluation of the incremental visual impact deriving from the comparison between the ante and post-operam state.