A critical evaluation of visibility analysis approaches for visual impact assessment (VIA) in the context of environmental impact assessment (EIA)

Visual impact assessment (VIA) concerns the identification and evaluation of the potential impacts that a proposed activity might have on the visual quality of a landscape and makes an important contribution to decision making in the environmental impact assessment (EIA) context. Visibility analysis is often used to assist in determining these impacts through a variety of approaches employing different techniques and data inputs. This paper identifies the visibility analysis approaches often used in VIA practice by reviewing a sample of VIA reports representing eleven (11) countries. The identified approaches were then evaluated for accuracy across differing landscapes through a total of 72 simulations. Analysis of variance was used to determine the sensitivity of the identified approaches to different variables within different landscape contexts. The type of digital elevation model (DEM) used was found to be the most significant variable affecting accuracy across all landscapes, while the technique used had some significance and resolution little significance.