Assesment of the Values of the Historic Urban Landscape of ValiAsr Street in Tehran Using PPGIS

Historic Urban Landscape (HUL), a notion which was introduced in 2011 by UNESCO, has a broad perspective larger than 'historic centers' or 'complexes' and consider the vast environment of a city in its geographic setting. This notion combines multiple interrelated layers of historical and cultural values, social experiences, economic processes and intangible, emotional and perceptional measures. This research tried to provide a typology of the multilayered values of one of the most important cultural and historic axis of Tehran, the Valiasr street based on the available state of the art, specifically people's opinion. The aim of the research was to prioritize the conservation plans with HUL approach and focus on the zones with the unbalanced situation of values. For this purpose, different values of the street were assessed by using PPGIS based on the people's opinions. Valiasr street with more than 12 decades of history represents different pieces of evidence of HUL such as gradual evolution, interaction with the geographical setting (like the topography), and natural or built green landscapes. The street has a length of 17.2 km and hosts varied urban functions such as commercial, green spaces and recreational, residential, administrative and educational activities. The research started with the study of the notion of Historic Urban Landscape and its values based on different national or worldwide theories and documents of WHC, ICOMOS, etc. It continued with identifying different layers of HUL values of the Street such as a memorial and historical, landscape and aesthetic, natural and ecological, cultural and recreation, and economical and usage. These values were elaborated by field surveys and interviews with people in the street. Later, the street was divided into 12 zones and a questionnaire was designed to asses the values by acquiring people's opinion (300 people on the street) in each zone. The weight of each value and the spatial distribution of the results was conducted using Public Participation GIS, specifically Average Nearest Neighbor analytic tool. The results of the research were reflected as point density on the site plan of the street. The map showed that areas with the natural landscape, mixed-functions or spectacular monuments have the highest density of values, even if they are not historically important. Specifically, this street is recognized by rows of plane trees on both sides, view of Alborz mountains in the north, or famous parks with a mixed border with sidewalks. People considered zones with these features as the most valuable ones. However, the southern part which is adjacent to the historic core of Tehran showed the lowest assessment. Superimposing the results of the assessment on the functional or physical attributes of the street can demonstrate the contradictions between the low assessment of the values by people and the rich historical and cultural contexts such as the south part of the street. It helps management plans to prioritize the conservation activities and focus on critical zones to be able to flourish all the multilayered values of heritage places specifically with a focus on natural or aesthetic values.