Assessing the visual landscape of Istanbul Bosphorus: Exploring the role of vegetation and built environment characteristics

Istanbul Bosphorus is one of the most important protected landscapes of Türkiye with its dramatic topography, natural landscape, and historical and cultural heritage embedded within this natural setting. However, studies focusing on the visual landscape assessment (VLA) of Bosphorus are limited. The main goal was to evaluate the VLA of Bosphorus and to understand the users' perception of this multi-layered landscape via utilizing VLA based on the evaluation of 45 photographs taken from the sea. For this goal, the study investigates the environmental texture proportion (ETP: vegetation, built environment, sea, and sky) and RGB values of the photographs using parameters such as naturalness, beautiful scenery, disturbance, excitement, safety, and livability in 5-Likert's scale. Findings demonstrated that photographs with more vegetation than built environment, with those containing 10 % or more vegetation receiving higher overall scores. Vegetation showed a high positive correlation with naturalness, beautiful scenery, excitement, safety, and livability. Moreover, disturbance was positively correlated with the built environment, and negatively correlated with vegetation. Namely, the most problematic ETP type for VLA was the built environment in Bosphorus. The study further identified built environment characteristics as a critical environmental component, with historical and mansion-type buildings scoring higher than other building types. Another important finding was that certain user features, such as gender, influenced perceptions of beautiful scenery (9 p-value), excitement (10), safety (11), and livability (21), while usage frequency affected perceptions of excitement (14) and safety (13). In other words, men gave higher scores to photographs compared to women, and users who regularly utilized the study area rated the photographs more favorably than those who used it less frequently. In conclusion, the study found that user characteristics of gender and usage frequency were influential factors, and vegetation (10 % and above) was the most paramount element for preferences when considering the visual landscape of the Bosphorus in Istanbul.