Qualitative effects of morphological change of character areas: Senesenevler, levent and kosuyolu single-family housing settlements

Considering the applications for the development of the city and the housing stock produced in Istanbul in recent years, it is obvious that planning and design decisions are taken without regarding the morphological and qualitative characteristics of the built environment. The environments we live in are rapidly changing, especially after the increase in building densities in the newly built houses that were demolished within the existing urban fabric. In newly formed environments, it is seen that spatial quality and human-based design principles are ignored. It is realized that these rapid changes cause the character areas, which are distinguished by their formal and spatial features in the urban fabric, to lose their original qualities. This thesis focuses on examining the effects of the formal, functional, spatial, and quantitative changes that the city has undergone in the historical process on the quality of the urban space through character areas. For this reason, the study is related to both urban morphology and urban design disciplines, considering the relationship of both with urban form. Due to the potential of urban morphology studies to provide fundamental information that guides both urban design and planning decisions, different approaches are needed to integrate these two disciplines or strengthen the bond between them during the formation and change of the urban fabric. These approaches are worth investigating to increase the quality of urban space. In addition, it is known that there is a requirement for studies on the qualities that create the character of the space in urban form studies. Also, another important research gap, which is discussed frequently in morphology symposiums, is the morphological character areas are ignored in planning decisions. These decisions provide only quantitative control in our country and cannot provide a qualitative approach to spatial quality and character. For this reason, there is a necessity for studies on how to include character areas in the planning system or how to create special planning and design decisions for these areas. In addition, morphological studies are mostly concentrated in urbanism and planning disciplines and the methods used are based on representations such as cartographic or digital models. Because of that, the conceptual and instrumental knowledge of architecture and urban design disciplines has the potential to make significant contributions to morphological studies. As mentioned above, the research problem is briefly based on 'the lack of different approaches and tools of representation in which spatial quality is centered instead of quantity in order to design more qualified urban spaces in the process of changing the urban form, to preserve the existing spatial quality and morphological character, and also to integrate urban morphology and design'. In this direction, the main aim of the study is to examine the effect of the morphological and quantitative changes that the character areas have undergone in the historical process on the quality of the urban space. During this examination, it is aimed that the concepts used as quality criteria in urban design (human scale, density, diversity, enclosure, coherence, and continuity, etc.) and architectural representation tools have a binding role in establishing the relationship between quantitative and qualitative changes. It is also intended to include these concepts in morphological studies and to ensure that they are effective and directive in studies, designs, and practices for the formation of more qualified urban spaces. Within the scope of the research, single-family housing settlements, which were designed and built between 1945 and 1960 in Istanbul with the influence of Ebenezer Howard's garden city idea, are evaluated as morphological character areas in today's urban fabric. Senesenevler, Levent, and Kosuyolu neighborhoods are examined for the thesis as types of these settlements. The development of Senesenevler is not limited by any conservation or planning decisions. Levent Neighborhood is an urban protected area today. And Kosuyolu Neighborhood is limited by the development plan notes. Therefore, they are important for morphological analysis as they have traces of different processes of change and their effects. In the first chapter of the research, the aim, scope, and method of the thesis are explained. In the second chapter, the contextual and conceptual background of which the processes in the formation of single-family housing and design principles are examined as a morphological character area. In the next chapter, the conceptual and methodological foundations of urban morphology studies are covered. Then, quality measurement concepts predicted to be effective in strengthening the relationship between morphology and design are focused on in the third chapter. In the fourth chapter, the morphological and quantitative changes in Senesenevler, Levent, and Kosuyolu settlements are analyzed. Afterwards, the changes identified through morphological elements are associated with the concepts of human scale, density, diversity, enclosure, coherence, and continuity. Thus, the effect of the morphological changes on the quality of the urban space is revealed with its positive and negative aspects. In the fifth and last part, the results of all research findings are compiled, the goals and research questions of the study are reviewed, and the importance of the study and its theoretical, practical, and methodological contribution to urban morphology research are evaluated. In addition, suggestions are made for planning, design, and implementation and for researchers who will work on similar topics in the future. During the morphological field analysis, firstly, the changes that the settlements went through in the historical process are revealed. For this purpose, the changes in both neighborhood and street-plot scales are analyzed over the situations of the settlements in 1966 and today (2021). Thus, changes in the settlements are investigated holistically at different scales through physical, spatial, morphological, quantitative, and graphic data. In order to understand the effects of these changes on the quality of the urban space, the morphological elements, whose continuity or discontinuity were analyzed in the previous section, are associated with the above-mentioned concepts. In this way, it is achieved how the morphological character and spatial quality of the settlements were affected or changed. While establishing this relationship, three-dimensional architectural representation tools and section drawings, which are useful in creating the volumetric representation of the urban space, are used. The research findings show that usually, the morphological changes seen in the settlements affect both the character of the built environment and the quality of the urban space negatively. It is observed that especially with the GSI and FAR changes in the settlements, the building densities are increased, the soft edges that allow human-scale interaction disappear with the constructions in the front yards, and the perception of enclosure in the streets changes with the increase in building heights. Along with these, we can see that the continuity of the green and void tissue of the neighborhoods and the coherent integrity of the tissue created with a common planning language are disrupted. It is acquired that the density increases detected above the ground are also observed at the underground level, and the continuity of the soil cannot be ensured due to the destruction of the natural morphological structure in the settlements. One of the other important findings is that the commercial density is increased due to the changing functions of the houses, especially in Levent and Kosuyolu. Although this situation provides a diversity of functions in the neighborhoods, it causes a decrease in the density of the dwellings and residents that form the character of the settlements. It is concluded that the historical and spatial context, morphological character, and spatial quality of character areas are ignored in the conservation laws, the restrictive construction notes, and the construction law. In these areas, there are uncertainties about how the change and development of the built environment will be in design and practice. In addition, it is considered that the change and development of these areas are left to the construction decisions determined based on plots. The decisions taken based on plots are not adequate to protect the physical and spatial characteristics or morphological character of the settlements as a whole. In addition, it is seen that the concepts used in determining the quality of the urban space can be important connectors between morphology and design, and three-dimensional architectural representations can play an important role in the spatial thinking of the urban space.