Akarsu koridorlarında tasarım ve planlama stratejilerinin belirlenmesi: Bir model önerisi

Abstract

Akarsular binlerce yıldır insan yerleşimlerinin önemli bir parçası olmuştur; kentler ilk olarak `akarsular arasında` doğmuş ve gelişmiştir. Sunmuş oldukları ekosistem servisleri ile akarsular günümüz kentlerinde de en az tarihsel süreçte olduğu kadar temel bir role sahiptir. Ancak hızlı kentleşmeye bağlı olarak akarsu koridorları gibi kırılgan bir ekosistemin sürdürülebilir olmayan müdahalelerle değiştirilmesi, akarsuların kentler için hayati olan ekosistem servislerini sağlama kabiliyetini ciddi şekilde azaltmıştır. Akarsuların kentler için önemli bir doğal kaynak olmasına karşın büyük ölçüde zarar görmüş olması bir çok araştırmacının dikkatini çekmiş; sorunların çözümüne dair geleneksel mühendislik yaklaşımının aksine bütüncül bir yaklaşım vurgusu sıklıkla yapılmıştır. Akarsu koridorlarına sorun bazlı geleneksel mühendislik yaklaşımları yerini; entegre, sürdürülebilir, bütüncül, ekolojik ve interdisipliner bir yaklaşıma bırakmıştır. Bu yaklaşımdaki yönlendirici parametrelerin doğru anlaşılması ve benimsenmesi, akarsu koridorlarının sürdürülebilir tasarımı ve planlaması sürecinde yol gösterici olacaktır. Bu bağlamda tez kapsamında, akarsu koridorlarının sürdürülebilir tasarımı ve planlaması için stratejilerin belirlenmesine yönelik bütüncül bir model ortaya koymak amaçlanmaktadır.Çalışma; literatür taraması, modelin oluşturulması ve modelin test edilmesi olmak üzere üç aşamada kurgulanmıştır. Literatür taraması kapsamında, akarsu-kent ilişkisinde ortaya çıkan sorunlar belirlenmiş ve tüm bu sorunların çözümüne yönelik stratejik yaklaşımlar bütüncül ve disiplinlerarası bir yaklaşımla incelenmiştir. Bu bütüncül ve interdisipliner yaklaşımın tezin amacına uygun olarak bir model üzerinde tariflenebilmesi için de literatür taramasında incelenen araştırmacıların üzerinde durmuş olduğu temel kavramlar kullanılmıştır. Kavramlar çok katmanlı olarak analiz edilmiş ve literatür taraması ile entegre edilerek bütüncül bir model ortaya konmuştur. Geliştirilen model, seçilen vaka çalışmalarına entegre edilerek dünyadaki çeşitli kentsel akarsu projeleri incelenmiştir. Kullanılan projeler akarsu tasarım ve planlama sürecine farklı bakış açılarını içermeleri sebebiyle farklı ülkelerden seçilmişlerdir. Aynı zamanda akarsuyun restorasyon öncesi durumunda geleneksel mühendislik uygulamaları ile ekosistem servislerini yerine getiremeyecek duruma gelmiş olması belirleyici bir özellik olmuştur. Bu kapsamda kullanılan projeler: Isar-Plan, Cheonggyecheon Nehri Restorasyon Projesi, Kallang Nehri-Bishan Bishan-Ang Mo Kio Park Projesi, Aire Nehri Yenileme Projesi, San Antonio Nehir Geliştirme Projesi (SARIP) ve Porsuk Nehri Rehabilitasyon Projesi'dirTez kapsamında akarsu koridorlarındaki sorunların temelinde yatan sebebin hızlı ve plansız kentleşme ile populasyon artışı olduğu sonucuna ulaşılmış; bu sorunları yaratan etmenlerin ise çok geniş bir perspektife yayıldığı tespit edilmiştir. Sorunların çözümüne yönelik stratejik bağlamda geliştirilen yaklaşımlar incelendiğinde ise konuların çeşitlilik arz ettiği ancak zengin ve geniş kapsamlı alternatiflerin olduğu görülmüştür. Bu çeşitlilik farklı disiplinlerin sürece katkısını gerektirmektedir. Bu durum akarsu koridorlarına stratejik yaklaşımda interdisipliner ve bütüncül yaklaşımın önemini ortaya koymaktadır.Çalışmanın tüm sonuçları değerlendirildiğinde akarsu koridorlarına planlama ve tasarım bağlamında yaklaşımın akarsu ekosisteminin tüm dinamiklerini gözeten, bütüncül ve interdisipliner bir yapıda olması gerektiği görülmektedir. Oluşturulacak stratejiler için bir yol haritası olarak tez kapsamında önerilen bütüncül model, akarsu koridorları kapsamında birçok parametreyi değerlendirmesi ile literatüre katkı sağlamaktadır. Model akarsu projelerinin tasarımı ve planlanmasında dikkate alınması gereken temel konular olan taşkın güvenliği, ekolojik koruma ve sosyal gelişim konuları bağlamında farkındalığın arttırılmasına yardımcı olacaktır.

Rivers have been an important part of human settlements for thousands of years; cities were born and developed `among the streams.` With the ecosystem services they offer, rivers play a fundamental role in today's cities as well as in history. However, due to rapid urbanization, the replacement of a fragile ecosystem, such as river corridors, with unsustainable interventions has severely reduced the ability of rivers to provide ecosystem services vital to cities. Although the rivers are an important natural resource for the cities, urbanization alters them a great extent, and this situation attracted the attention of many researchers.In contrast to the traditional engineering approach to solving problems, urban environments deserve a holistic approach. An integrated, sustainable, holistic, ecological and interdisciplinary approach should replace problem-based traditional engineering approaches to stream corridors. Correct understanding and adoption of the guiding parameters in this approach will guide the process of sustainable design and planning of river corridors. In this context, this research puts forward a holistic model for defining strategies for sustainable design and planning of river corridors.The study comprises three stages: literature review, creating and testing the model, and generating recommendations. The literature covered in the thesis has two sections. The first section involves information about the importance of rivers for nature and cities, ecosystem services of streams, historical evaluation of the usage of rivers and problems that arise in the context of river-city relationships. The second section of the literature review comprises different strategic and interdisciplinary approaches for the design and planning process of river corridors. These strategic approaches which belong to different researchers from different disciplines form solutions for the problems mentioned in the first section of the literature review. In the light of the second section of the literature review, 'Term Map' emerges from important keywords and main ideas from different strategic approaches and sets up a substructure of a holistic model for defining strategies for sustainable river corridors. Subsequently, the literature review yielded the primary components of the model.The issue of determining sustainable strategies for river corridors is a phenomenon that includes dynamic processes between different actors and different criteria. That is why holistic model proposed in the thesis aims to determine the interaction of components within the context of the process of river corridor planning and design and consequently to form strategies for the mentioned process. The model formed by three different inputs as 'Term Map'that yielded from a literature review, researcher – term relationship table and weighted terms visual. Analysis of these three different inputs was evaluated over Gephi. Gephi is an open-source software used for network analysis, and it can also work integrated with the Excel program. In this way, graphics, maps,and visuals based on statistical calculations yield relationships of the data presented to the program.The three different inputs that mentioned before came together and formed inclusive perspectives to create a model to produce strategies for river corridors. After the evaluation of these three different inputs, inclusive perspectives emerged to generate strategies for river corridors. Accordingly, the perspectives fall under three categories: Flood Safety and River Perspective, Ecological Protection and Nature Perspective and Social Environment and Urban Perspective.Finally, the scrutiny of case studies took place to reassure the primary components of the model. Reading the model through successful river restoration projects around the world enabled testing of its compatibility. The selected projects are from different countries to include different perspectives on the stream design and planning process. Also, the condition of the river before the restoration / rehabilitation project that was completely lost its ecosystem services by traditional engineering practices was an important criterion in the selection phase of the projects. The case studies included Isar-Plan, Cheonggyecheon River Restoration Project, Kallang River-Bishan Bishan-Ang Mo Kio Park Project, Aire River Renaturation Project, San Antonio River Development Project (SARIP) and Porsuk River Rehabilitation Project.With the scrutiny of case studies, evaluation of each strategic perspective in the model was done by matching them with its equivalents in the implementation scale. As a result, each perspective and term in the model matched with an implementation in the successful project. This proves that the model can be used to generate strategies for design and planning projects for river corridors. Another result coming from case studies was that the decision taken for each strategic perspective directly constituted an input to another perspective and this situation is an important indicator of the holism of the proposed model.The condition of rivers and water resources, which is one of the most important environmental topics in the agenda of modern societies, is also one of the main issues of planning and protection in Turkey. As Turkey has many basin physiographic structure; this carries rivers to an important place in the context of planning and design. For this reason, the institutional structure and legal situation regarding the management of water resources and rivers in our country took place in the discussion part of the thesis. In this context, according to the results from research and literature review, policies should be developed to solve the confusion of authority between different institutions, to meet the needs of rivers at different scales, and to support the identity of rivers and water resources in the city. These policies should have a holistic character and involve the main perspectives in the model as flood safety, ecological protection, and social environment perspectives. There is a need for an integrated legal arrangement covering both river corridors and water resources.Within the scope of the thesis, rapid urbanization and population increase occurred as the main reason for the problems in the river corridors; and the factors causing these problems spread to a wide perspective. Approaches developed in the strategic context for the solution of these problems have a rich and comprehensive character in parallel with the problems. This rich and comprehensive structure also describes the diverse issues of design and planning of river corridors. This diversity requires the contribution of different disciplines to the process. This situation demonstrates the importance of an interdisciplinary and holistic approach in strategic planning and design of river corridors.Also, each river corridor has a unique structure with its unique features and dynamics. This situation requires observing the dynamics specific to the area within the scope of the strategies to be produced. The techniques applied under the strategies are created by analyzing the different features of the relevant river corridor.Flood protection, ecology, and social values are major considerations to create strategies during the design and planning of river corridors. Also, contributing experts from different disciplines to the process is very important. Within the framework of the sustainable development approach, there is a need for an environment where many disciplines work together, especially for the design and planning process over a complex structure such as river ecosystems. Strategies that have holistic and interdisciplinary character will bring many social, ecological, environmental, aesthetic, and economic benefits to the river corridor.All in all, it is seen that the approach to stream corridors in the context of planning and design should be integrated and interdisciplinary, considering all the dynamics of the river ecosystem. The holistic model proposed as a road map for the strategies contributes to the literature by evaluating many parameters in the context of river corridors. The model will help to raise awareness of the basic issues in the design and planning of river projects.