Development of sustainability indicator set in medium-sized cities: An evaluation in Düzce and Bilecik provinces

Cities are seen as centers of attraction due to socio-economic developments that increase people's quality of life. When the population projections are examined, it is stated that more than two-thirds of the world's population will be concentrated in urban areas by 2050. However, the uncontrolled growth of urban areas in meeting the needs of the increasing population has a negative effect on natural resources. Therefore, it is necessary to adopt a sustainable urbanization approach by using limited natural resources in line with the needs of future generations. Sustainable urbanization aims to increase the socio-economic quality of life by ensuring the rational use of natural resources, minimizing the use of non-renewable resources, meeting the basic needs of people. One of the important outputs of the Rio Conference in 1992 is the Agenda 21 document and it is emphasized that indicators are an important tool in the evaluation of sustainable urban development. Indicators make information about the current situation in urban areas meaningful in the light of rational data. The aim of this study is to reveal a method approach for determining and evaluating appropriate indicator sets that will ensure the sustainable development of medium-sized cities. In this context, sustainability performances were calculated through indicators determined for environmental, social and economic sustainability, which are the three main components of sustainable development. As a result of the evaluations, it has been determined that the performance score of Bilecik province is good in terms of environmental, social and economic sustainability. The performance score of Düzce province in terms of environmental, social and economic sustainability has been determined as medium. As a result, this study is an important guide for researchers to develop systematically appropriate indicator sets in future studies. Thus, by means of indicators, it is possible to identify the problems encountered in the sustainable development of cities and to develop policies for the solution of these problems, and to make necessary revisions by monitoring the developed policies.