Scenario-Based Land Use Estimation: the Case of Sakarya
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ITU A|Z • Vol 12 No 1 • March 2015 • 181-203 Scenario-based land use estimation: The case of Sakarya Fatih TERZİ [email protected] • Department of Urban and Regional Planning, Faculty of Ar- chitecture, Istanbul Technical University, Istanbul, Turkey Received: July 2014 Final Acceptance: January 2015 Abstract This paper presents scenario-based modelling of urban land use which stem from interactions of the urban functions of Sakarya, one of the most important city for agricultural production and a vulnerable region in terms of natural re- sources and seismicity in Turkey. The purpose of the paper is to estimate the fu- ture land use pattern of Sakarya and discuss the environmental effects of alterna- tive spatial policies. ‘Whatif?’ approach which allows the users to develop various scenarios, provide a basis to measure the impact of new development areas on natural environment and revise the policies easily in relation to the land use esti- mation model results and future urban development pattern. Keywords Land use, Land use policy, Sustainable development, Urbanization. 182 1. Introduction The paper has two objectives: The Estimation of future land use pat- first objective is to provide an input for tern are critically important for un- the land use planning, and the second derstanding the effects of alternative one is to develop the alternative local planning decision and assessing their land development strategies in the fu- impact on the environment in urban ture. The organization of the paper is planning process. Generally, the tech- as follows: The literature review related niques of future land use estimation to urban spatial modelling have been cover spatial and temporal processes. addressed in the second part. This These are the techniques which in- part is followed by the background clude uncertainty factor and developed information of case study area. In the on the basis of the alternative scenar- fourth part consists of methodology ios. Nowadays, urban growth model- and modelling procedure followed by ing studies witness a change towards the discussion section. The paper is -fi building ‘what if’ scenarios and dom- nalized with concluding remarks and ination of these scenarios over many the implications of the research for the modelling efforts (Batty and Torrens, future. 2005). ‘Planning Support Systems’ (PSS) constitute an informatics roof 2. Literature review: Modelling of ur- which unites all current and future in- ban spatial development formation technologies used for plan- As the human communities have be- ning with three concepts: information, come more dependent on the natural model and visualization (Klosterman resources, it is progressively becoming 1999; Geertman and Stillwell, 2004). an obligation to protect these natural Considering restraints of the planners resources, sustain the biological di- about the use of sources and informa- versity and ensure continuation of the tion, an approach of improving alter- healthy urban mechanism. The urban native ‘scenario-based estimations’ by planning which aims to organize the using the available database has been human actions by protecting the nat- introduced, instead of giving a precise ural resources and ensuring their sus- forecast about the future (Klosterman, tainability faces an increasing uncer- 1998). tainty about the future. The interaction This paper presents scenario-based between the human communities and modelling of urban land use which natural systems is of vital importance stem from interactions of the urban for the successful functioning of a city functions of Sakarya, one of the most (Barredo et.al, 2003; White et.al, 1997), important city for agricultural produc- and the land use pattern is emerged as tion and a vulnerable region in terms a result of these interactions. Howev- of natural resources and seismicity in er, it is very difficult to understand the Turkey. Modelling the prospective ur- nature of these interactions that are ban growth of Sakarya based on differ- tried to be explained by urban systems ent development scenarios is expected modelling (Openshaw, 1995). The ur- to contribute to the assessment of the ban modelling is building and execut- future urban development of Sakarya ing the complex mathematical models and determination of the strategies in order to estimate the urban growth regarding the future. Therefore, this form in the future with the aim of sup- paper aims to estimate the future land porting the planners, politicians and use pattern of Sakarya and to discuss other decision-making mechanisms. the environmental effects of alternative Role of the models in the planning spatial policies. In this paper, ‘what- process is to understand the behaviors if?’ model was used, since it allows the of the urban systems and help perform users to formulate various scenarios the urban development in compatible and select the most appropriate one with the public policies (Batty, 1976). among these and assess its impacts. In It is essential to analyze the land addition, this model provides the users use dynamics in the urban modelling with the opportunity to revise their as- approaches in order to understand sumptions and policies easily in rela- the urban functioning. The fact that tion to the model results. densely populated cities exhibit urban ITU A|Z • Vol 12 No 1 • March 2015 • F. Terzi 183 expansion towards forests, wetlands classical urban transportation model and agricultural lands results in rap- known as four-step model was widely id depletion of the natural resources used, but this modelling techniques and degradation of the ecosystems. were found quite static. Growing un- Therefore, information concerning ur- derstanding of the impact of the in- ban growth rate, spatial development teraction between cities and transpor- form and concept is necessary for the tation systems on urban growth have planning strategies to designate the re- led to develop Integrated Land Use serves and capacities of the future nat- Transport (LU-T) Model (Sivakumar, ural resources and understand the cur- 2007). Earlier version of LU-T mod- rent and future impacts of the land use el was tried to be explained by gravi- changes. Estimating the future envi- ty type models, first one of which was ronmental results of the urban growth developed by Lowry in 1964. Later on, requires to forecast such changes in such integrated LU-T models as ME- land use and their effects on the natu- PLAN by Echenique, (1985), MUSSA ral resources. by Martínez (1992), and UrbanSim by One of the most important challeng- Waddell (2002) were developed to bet- es to be encountered by the natural and ter explain the interactions between social sciences in the years ahead will land use, transportation, the economy, be to understand the changes under- and the environment. Even though gone by the cities due to interactions of such LU-T models were developed and the humans and natural systems. There evolved, the 4-step model continues are so many complex processes in the to represent the transport modelling interaction of the cities with the nat- component (Sivakumar, 2007). ural systems and the change periods. Sivakumar (2007) groups the LU-T During this periods, urban systems are model in three category. The first subject to temporal and spatial chang- group is Travel Demand Models. This es as a result of the choices and actions type of models divide into five sub of the individuals. These choices and categories: Aggregate models, disag- actions are guided by the multiple fac- gregate trip-based models, tour-based tors. Households, business circles, real models, activity-based models and estate developers, managers, etc. are modelling freight demand. The second among the important factors of this group is operational integrated LU-T change. Households and business cir- models in which models grouped into cles decide about the production, con- two sub categories: Static models and sumption and selection of the location dynamic models. Static models are the within the city. Real estate developers earliest LU-T models which aim to are in search of the new investments. explain the relationships between the Managers decide the infrastructure land use and transportation systems. and service investments in consider- These type of models based on gravi- ation of the policies and laws. All these ty equations or input-output formula- decisions change structures of the eco- tions. Since early models approach the systems due to such actions as use of matter only from a mathematical per- the resources, conversion of the lands spective, land use spatial strategies and into the urban land, generation of policy analysis remains weak (Sivaku- emission and wastes. The recent mod- mar, 2007). Whereas, dynamic models elling studies conducted to understand defined as “…the development of im- the dynamic natures of the urban and proved modelling methodologies such natural systems concentrate on the re- as entropy-based interaction, random lations of the humans and natural sys- utility theory, bifurcation theory and tem (Alberti and Waddell, 2000). non-linear optimization, together with Another important challenge in ur- significant computational advances has ban land use modelling studies is to un- paved the way to the development of derstand the interactions between land dynamic land use-transport model sys- use and transportation system. Earlier tems” which divided into two catego- version of travel demand models were ries: General Spatial Equilibrium mod- based on estimating spatial