1 Introduction

Historically, cities have developed along coastlines because of local economic benefits derived through trade, defense, transportation, and access to food. For this reason, cities on the coastline have generally been critically important in terms of culture, history, and economy (Sandhu et al., 2019). Coastal cities are the center of attraction for residents and international activities worldwide. Ports and their associated economic activities, such as shipping and activities based on ecosystem resources, such as tourism, fishing, and aquaculture, are critical activities for this attraction function (Cummins et al., 2004; Hegazy, 2021). These features offer numerous advantages to coastal communities depending on the coast’s ecological, economic, scientific, and aesthetic values (Hegazy, 2021).

A city that fits the definition of a coastal city has a fully integrated urban life and system. Coastal cities, acting as a bridge between the coast and the land that continues behind it, represent a highly rich geography as they contain varying ecosystems. For centuries, the presence of water in cities has been the main factor shaping the city’s life, culture, and spatial organization. Additionally, water element in the coastal cities has provided significant advantages to the city by developing economic activities and transportation infrastructure (Chinnasamy & Parikh, 2021). The development of the city depends on how well the coast is used and how integrated it is with the city (Barragán & De Andrés, 2015).

Coastal regions represent 20% of the Earth’s surface, and a large proportion of the total urban population lives in the major cities (Brommer et al., 2009; Hegazy, 2021). Due to global trade activities and internationally operating ports, the coastal population is also growing exponentially (Tibbetts, 2002). In many countries, populations in coastal areas are growing faster than populations in non-coastal areas. For example, in 1950, New York was the planet’s only “megacity,” defined as a coastal city of more than 10 million people. Currently, there are 17 megacities worldwide, and 14 of them (New York, Rio de Janeiro, Buenos Aires, Shanghai, Tokyo) are located in coastal areas (Tibbetts, 2002). However, it also raises concerns that population growth and associated activities may harm coastal and marine ecosystems (Creel, 2003; Pramanik et al., 2016).

A wide range of studies have been carried out on various issues related to coastal areas in the world. These studies highlight the features that distinguish coastal cities from other cities. To be more specific, trade/port activities, coastal tourism, and traditional economic activities (Fishing, Agriculture, Aquaculture) (Balk et al., 2009; Creel, 2003; Dimitrovski et al., 2021; FAO, 2002; Hinrichsen & Olsen, 1998; Ji & Wang, 2022; McGranahan et al., 2005; Timmerman & White, 1997; UN-Habitat, 2009) are the criteria evaluated within the scope of economic development. In addition, the urban development and spatial growth trends of coastal cities, population density, coastal land uses, and the central nature of coastal areas (Barragán & De Andrés, 2015; Creel, 2003; Kpienbaareh & Luginaah, 2020; Schneider & Woodcock, 2008; Yilmaz & Terzi, 2021) have also been evaluated as differential criteria. The transportation factor in coastal cities is typically evaluated separately as transportation within the city and sea transportation between different cities and countries (Baird, 2009; Boulos, 2016; Chen et al., 2021; Corbett, 2004; Marsh, 2012; Polyzos & Tsiotas, 2012).

Turkey is a country with affluent coastal areas and an abundance of coastal resources. Turkey’s coasts are chosen for travel and tourism due to their natural beauty and cultural and historical values (Cengiz et al., 2022). While the Mediterranean and Aegean coasts are developing toward tourism, the cities around the Marmara Sea are developing toward the economy and industry (Kaypak, 2012). Therefore, it is necessary to monitor the coastal areas by considering environmental and economic as well as transportation aspects (Dogan, 2013; Guneroglu, 2015). Maritime transport in Turkey is developing under minimal conditions as it needs to be given special importance. When road transportation was not developed, the sea provided transportation between the settlements on the coast. However, due to the development of highways, sea transportation has lost its importance rapidly (Deniz, 2016). Maritime Administration, which has an important place in maritime transportation in Turkey, has withdrawn from the business of passenger transportation, and national and international passenger and vehicle transportation has started to be carried out by private companies. As a result, the share of passenger transportation in maritime transportation has decreased to almost non-existence (Avci, 2005; Deniz, 2016). The lack of unique coastal planning in Turkey, the destruction of the natural coastline with various construction activities, and the development of coastal transportation only for port activities despite being surrounded by sea on three sides reduce the quality and impact of coastal cities. Turkey has the characteristics of a port with its seas, but coastal cities have remained in the background because of the lack of proper urban planning and management.

The characteristics of coastal cities have been stated in different categories in different studies (Balk et al., 2009; Barragán & De Andrés, 2015; Chen et al., 2021; Creel, 2003; Dimitrovski et al., 2021; Ji & Wang, 2022; McGranahan et al., 2005; Timmerman & White, 1997; UN-Habitat, 2009; Yilmaz & Terzi, 2021). Despite the significance of economic activities, urban development, spatial growth and transportation factors in defining the identity of coastal cities, these elements have not yet been studied in a holistic approach. Moreover, it is worth noting that despite the growing interest in coastal cities, more empirical studies need to be conducted to evaluate the criteria set forth for such regions and subsequently determine their relative importance. This gap in the literature underscores the need for further research to address this critical knowledge gap and inform decision-making in this area. In light of the existing gap in the literature, the present study aims to bridge this gap by developing a systematic appraisal mechanism to uncover a coastal city profile. Even though Bursa, the subject of the study, is situated on the coast of the Marmara Sea in Turkey, it appears that the coastal regions are not given significant attention in the city’s overall spatial planning. Thereby, this research entails the development of a comprehensive coastal city evaluation system aimed at assessing the characteristics of Bursa’s coastal city in accordance with predetermined criteria. Based on the evaluation outcomes, suitable strategies will be formulated to address the identified issues and strengthen the city’s coastal management practices. In this context, for the first time, all criteria related to the coastal city were listed under main and sub-headings. Using AHP, an MCDM method, with a practical participatory approach, each criterion was digitized and ranked according to their essential priorities. According to the emerging priorities, planning and design strategies have been proposed for the city of Bursa to increase the quality of a coastal city. Unlike other coastal city studies, this research conducted in Turkey determined coastal city criteria comprehensively. For the first time, they were digitized according to their importance priorities with a participatory approach. This research employs a fresh and creative approach, making it exceptional in its focus on the key criteria for coastal cities and the corresponding recommendations it provides. Therefore, this study can be regarded as a noteworthy model for assessing Turkey and other coastal cities worldwide, and devising effective strategies to improve their overall qualities.

2 Material and method

2.1 Material: study area

The Anatolian Peninsula, together with the Thrace Peninsula in the northwest, forms the territory of Turkey. The coast has a border length of approximately 11,000 km and a coastline of 8333 km, including the islands in Turkey. The most extended 42% of the 8333 km coastline is on the shores of the Aegean Sea, 21% in the Mediterranean, approximately 21% in the Black Sea, and 1.5 km in the Marmara. Black Sea, Marmara, Aegean, and the Mediterranean are our regions in contact with the coast, and we have 29 coastal provinces in total (Kaypak, 2012).

The primary material of this study was the natural and cultural landscape value of the coastline of Bursa, which was chosen as the study area. Bursa is the fourth largest city in Turkey and the third largest city on the shoreline of Turkey. Thanks to its fertile plain, rich water resources, and close location to Istanbul and other international trade centers, it has been an important commercial center from the past to the present (İlhan, 2019). Located on the Marmara Sea, the city of Bursa is the second largest city in Marmara after Istanbul. Consequently, many coastal structures, especially transportation coastal structures, are on the Bursa province’s shores. The length of the coastline is approximately 115 km, and three districts within the boundary of the Marmara Sea of Bursa are Gemlik, Mudanya, and Karacabey (BBB, 2015) (Fig. 1). The coastal length of Gemlik, Mudanya, and Karacabey are approximately 38 km, 42 km, and 35 km, respectively (BBB, 2015). However, Fig. 1 also shows that these three districts are far from the center of the Bursa.

Fig. 1
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Location of study area and coastal part of the Bursa

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Being an essential industrial base in the region, Gemlik continues to develop in the industrial sector with its feature of being a coastal area with the fourth largest free zone in Turkey. This situation causes the demographic structure to change and increase; dense structuring is seen on the coasts (Bulut & Murat, 2019). Located 28 km from Bursa city center, Mudanya is a district of Bursa with a population of 54,000. Mudanya, which has an important place in the city in terms of intercity freight and passenger transportation with its developing tourism potential, has been closely related to Bursa’s economic and cultural developments (Polat & Dostoğlu, 2007). The coasts of Bursa province have suitable geographical conditions for tourism and recreation. Tourism investments, which have increased in parallel with the rapidly developing tourism sector in the city, have led to a significant increase in population, especially since 1990 (Kurt, 2015). As a result, while the population in the coastal districts of Bursa (Gemlik, Mudanya, Karacabey) was 145,050 in 1980, it increased to 510,902 in 1990 and 700,649 in 2013. Along the coast are land uses consisting of forests, protected areas, wetlands, and sand dunes (Fig. 2). However, with the increasing population, many of the agricultural and forest areas within the protection zone on the coast have turned into holiday sites and second residences. Considering the tourist population added in the summer months, it becomes clear that there is significant pressure on the natural and geomorphological structure of the province’s coasts (Kurt, 2015). There are olive groves for agriculture in the coastal area. However, it creates severe urban pressure on olive groves with tourism-based construction activities. Furthermore, according to the accessibility situation given in Fig. 2, only two main roads reach the coastal areas from the center of Bursa. Public transportation facilities are limited, and therefore, transportation to coastal areas is mainly provided by private vehicles.

Fig. 2
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Coastal landuse and accesibility of coastal areas (Gündüz & Aytaç, 2013)

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2.2 Method

The research process consists of four stages: determination of the current situation, (1) determination of the coastal city criteria, (2) quantification of coastal city criteria with AHP, and finally, (3) evaluation of coastal city potential and deficiencies and developing proposal strategies according to coastal city criteria to increase the coastal city potential (4) (Fig. 3). Each step is explained in detail in the following sections.

Fig. 3
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Analytical phases of research

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2.2.1 Determination of current situation

Economic activities, the city’s development rate, the existing settlement order, and transportation options are the primary elements that make up the character of a coastal city. For this reason, it is of great importance to read and evaluate these elements correctly in the city to understand the nature of the coastal city. For this reason, at this stage of the study, the economic activities of Bursa and the relationship of these activities with the coast were examined. During the review, data published by official institutions (Municipality, Environment and Urban Ministry, and Chamber of Commerce and Industry) and data of BEBKA (Bursa-Eskişehir-Bilecik Development Agency) data were used. In addition, the city’s spatial organization and land use status were analyzed using Corine 2018 data. Furthermore, using 2018 population data from the Turkish Statistical Institute (TUIK), the population density of the study area has been determined. In addition, the area’s transportation network was analyzed from the regional scale to the urban scale step by step. This current situation helped to understand the relationship between the center of the Bursa and the coastal region.

2.2.2 Determination of the coastal city criteria

At this stage, literature research was conducted covering coastal cities, the development of coastal cities, their characteristics, and previous studies on coastal cities. According to Table 1, which was created by considering the literature and the characteristics of coastal cities in different geographies, economic development (1), urban growth and spatial organizations (2) and transportation (3) were determined as three main criteria. Trade/port activities, coastal tourism, traditional economic activities (agriculture, aquaculture, fishing), coastal land use, population density, location of the city center, access to the city from other cities and countries, and inner access to the coastal zone were determined as sub-criteria of coastal cities in the decision hierarchy (Table 1). In the next step, these determined criteria were weighted with the AHP method, one of the MCDM methods, by taking the opinions of locals and experts. These criteria serve as a framework example for evaluating coastal city quality for other regions with coastal potential. These main and sub-criteria are explained in detail below.

Table 1 Main criteria and sub-criteria of coastal cities
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2.2.2.1 Economic development

Coastal cities such as São Paulo, Buenos Aires, and Jakarta prospered after the deregulation of financial markets, and their urban centers flourished with Western-style, high-income commercial and residential gentrification (Tibbetts, 2002). The economic attractiveness of the coasts in terms of tourism, logistics, industry, and services leads to population growth and urban spatial growth in physical geography. (Balk et al., 2009; Chinnasamy & Parikh, 2021; Hinrichsen & Olsen, 1998; McGranahan et al., 2005; Timmerman & White, 1997; UN-Habitat, 2009).

Coastal areas worldwide are important destinations for tourism, representing the fastest-growing global economic sector. Tourism dominates the economy of some regions and small island states. As a concrete example, tourism constitutes 95 percent of the economy of the Maldives and is the country’s only source of hard currency (Creel, 2003). Tourism can offer some environmental benefits, such as a greater appreciation of the value of natural resources. In the Caribbean, for instance, diving tourism has helped raise awareness about the need for reef conservation, but coastal tourism can also harm the coastal zone. It can lead to unsustainable coastal development as infrastructure is built on the shoreline to accommodate tourists. Nevertheless, tourism plays an important role, especially in the economic development of coastal cities (Dimitrovski et al., 2021). With a long coastline, broad sea areas, diverse climates, and many coastal cities, China has rich resources for coastal tourism (Ji & Wang, 2022).

Marine fisheries and aquaculture (the controlled cultivation and harvesting of freshwater and marine organisms) produce almost 100 million tons of fish, shellfish, and edible plants yearly, providing a livelihood for about 35 million people, most of whom living in developing countries. However, overharvesting to meet global consumers’ growing demand for seafood can deplete many species and alter the biological structure of coastal ecosystems (Creel, 2003; FAO, 2002).

2.2.2.2 Urban growth and spatial organizations

Changes in the size, composition and distribution of human populations affect coastal regions by changing land use and land cover (Creel, 2003). The agglomeration in coastal cities puts the coastal regions under the pressure of urbanization. In addition, coastal cities in developed countries or with trade relationships of strong port connectivity trigger urban growth (Kpienbaareh & Luginaah, 2020; Schneider & Woodcock, 2008; Yilmaz & Terzi, 2021). Thus, it is essential to understand and reveal how and where urban spatial growth will occur for future urbanization policies and strategies of coastal cities. Spatial growth characteristics vary based on urban growth in developed, developing, and undeveloped countries (Kpienbaareh & Luginaah, 2020; Schneider & Woodcock, 2008). In addition to the development levels of cities, natural thresholds are one of the most critical determinants in shaping cities. Coasts and topographic thresholds are attractive natural elements driving urban growth (Yilmaz & Terzi, 2021). Therefore, it is also important to focus on the types and geometries of urban growth to produce sustainable spatial policies in coastal regions over time.

The average population density in coastal cities or coastal areas of cities is higher than the population density in other residential areas (Creel, 2003). About 50 percent of the population in North Africa and Bangladesh lives in coastal areas, and along the Nile Delta, population density reaches 500 to 1,000 people per square kilometer (Creel, 2003). With the denser population in coastal cities, urbanization activities are also more intense, and coastal areas are considered centers when economic advantages are taken into account (Barragán & De Andrés, 2015). As seen on the political maps of the world, the location of most capitals is either very central or located in coastal areas. Near port and peripheral maritime positions are often seen in countries that were former colonies of overseas powers (Barragán & De Andrés, 2015; Creel, 2003; Gottmann, 1983).

2.2.2.3 Transportation

Transport infrastructure drives development from the coast to the inner city areas (Baird, 2009; Boulos, 2016; Polyzos & Tsiotas, 2012). It acts by developing the city-port link as an effective pillar of economic growth. Access by different modes of transport, such as trains and trucks, is vital for connecting the city and the port so that passengers and freight can move further inland and into the city center beyond the port area (Boulos, 2016).

In the past, shipping was one of the most used ways to reach overseas countries or cities (Chen et al., 2021; Corbett, 2004). In the twenty-first century, shipping is an integral part of the global economy, although it sometimes needs to be more visible to the public. Today, although domestic transportation via maritime transportation has left its place for road and air transportation, maritime transportation in coastal cities is an important alternative with no traffic problem. The maritime transport system between countries comes to the fore in a more commercial sense (Chen et al., 2021; Corbett, 2004). The maritime transport system is a network of ships, the ports they visit, and the transport infrastructure that stretches from factories to terminals. Worldwide, approximately 44,000 offshore vessels carry more than 33 billion tons of cargo annually (Corbett, 2004). In addition, within the scope of cruise ship tourism, both sea transportation and tourism activities, which are economic activities, are carried out between countries (Marsh, 2012).

2.2.3 Quantification of coastal city criteria with AHP

The AHP method was introduced by Saaty (1980) as a model that is frequently used in MCDM problems, handles the relative importance of criteria, effortlessly combines expert decisions, and solves complex decision-making problems in a simple hierarchical order with a flexible approach (Hadipour et al., 2020; Zhang et al., 2022). This method has multiple stages: structuring the model, prioritizing the criteria, and integrating the priorities (Hadipour et al., 2020; Saaty, 1980). The AHP method converts verbal data into numerical data, is easy to understand and interpret the results, and works with a limited number (until nine criteria) of criteria (Demir et al., 2016; Tajer & Demir, 2022). For this reason, the number of criteria determined is essential for the results to be accurate and reliable.

The AHP method is frequently used as an MCDM method (AHP-DELPHI-Fuzzy AHP- TOPSIS) in coastal studies in the last 5 years such as sea level rise and flooding problems, climate change and vulnerability, coastal tourism, and land use issues (Table 2). However, Table 2 also shows that this method has not been used in a study to prioritize the criterias of coastal cities.

Table 2 Coastal city researches with AHP method
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Within the scope of this study, the reason for using the AHP method is that it is the first study to evaluate the coastal city criteria, and the number of criteria (three main criteria and nine sub-criteria) is suitable for this method. For this reason, this research is both original, and the evaluation process of the results is accessible and understandable. In this context, to prioritize the criteria, a questionnaire was created so that the criteria were compared in pairs. First, the main criteria were evaluated among themselves, and then the sub-criteria were evaluated under each main criterion. At the end of the AHP analysis, each criterion received a priority value in its category by calculating its eigenvalues. Within the scope of the evaluation, the population of the neighborhoods in the central districts and coastal districts was selected to determine the number of questionnaires. Thus, a total population of 2.362.343 was obtained for the Bursa city center and coastal districts according to the Bursa 2021 census. The survey was to be carried out with at least 385 people for a confidence interval of 95%, and it was finally carried out with 391 individuals face-to-face. Those who participated in the survey were divided into 2 groups including locals and experts. In the questionnaire surveys which were conducted in one on one interview, the local participants were chosen randomly from the fields of the study and asked to allocate 10 min for the survey. The expert group consists of landscape architects, architects, city planners, and personnel working in the port and tourism sector in Gemlik and Mudanya Districts. 340 local people and 51 experts were interviewed to evaluate the main and sub-criteria. The following formula was used to determine the sample size (Ozdemir Isik & Demir 2017; Tajer & Demir, 2022):

$$n = \frac{{{\text{N}} \times {\text{P}} \times {\text{Q}} \times t^{2} }}{{\left( {{\text{N}} - 1} \right) \times d^{2} }}$$

n = Sample size, N = Population size (2.362.343), t = Table value (1.96), P = Percentage picking a choice (0.5), Q = (1 − P) Percentage unpicking a choice (0.5), d = Error margin (0.05).

The data were transferred to the Microsoft Office Excel (2020) program at the end of the survey process. The average of each data in the survey was calculated with the help of Expert Choice 11 software for studies conducted with the AHP method to be acceptable, and the consistency ratio should be less than 0.10 (Aydin et al., 2009; Demir & Atanur, 2019; Ozdemir Işik & Demir, 2017). In this context, the consistency rate of this analysis was obtained for the main criteria as 0.01 and sub-criteria as 0.085, 0.016, and 0.092 with an acceptable accuracy rate.

2.2.4 Suggestions for the development of coastal city qualities

This research was conducted with a participatory approach to objectively determine Bursa’s coastal city potential. Given this, in the last stage of the study, the features and potentials of the coastal city of Bursa and its limitation were determined, and offered strategies to increase the coastal city’s potential of Bursa according to the prioritized criteria.

3 Results

A total of 391 people, including experts and local people, participated in this study, in which the coastal city qualities of the city of Bursa were evaluated. According to the results of this survey, all components of the AHP analysis are listed numerically according to their priorities, and the weight value of each component, together with its consistency rate (CR), is shown in Table 3. According to the results among the main criteria, the criteria are respectively; “Economic Development” (0.41), “Urban Growth and Spatial Organizations” (0.34), and “Transportation” (0.25) were weighted (Table 3). According to this result, the economic development of the city shows that it should be more effective in strategies to increase the quality of the coastal city.

Table 3 Prioritization of coastal city criteria with the AHP method
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According to Table 3 “Trade and port activities” (0.16), which is one of the sub-criteria of “Economic development,” is determined as the highest priority criterion. In contrast, “Traditional economic activities (fishing, agriculture, aquaculture)” (0.08) is the least priority sub-criteria. This result shows that the economic activities that make a coastal city stand out are due to trade and its ports. “The location of the city center” (0.18), one of the sub-criteria under the title of “Urban growth and spatial organizations,” has been determined as the top priority criterion. Therefore, its weight value has been determined as the total top priority coastal city criterion. In the same category, “Urban population density distribution” (0.05) was chosen with the least priority. In addition, it was determined as the coastal city criterion with the least weight among all the criteria. Among the sub-criteria of “Transportation,” “Inner access to the coastal zone” (0.17) was determined as the highest priority criterion. In contrast, “Transportation from different countries to the city” (0.06) was determined as the minor priority criterion (Table 3).

Considering the general ranking of the coastal city criteria according to their weight values, “The location of the city center” (0.18) was determined as the most prioritized criterion (Table 3). This result shows that coastal areas, the main elements of coastal cities, should be close to that city’s center and the main center of all economic, urban, and social activities. Among all these criteria, “Transportation to the inner city shore” (0.17), a transportation sub-criterion, was the second highest priority criterion. In contrast, “Trade and port activities” (0.16), which is the sub-criterion of economic development, was determined as the third highest priority criterion. When the criteria with the highest weight value and therefore the first three priority criteria in Table 3 are examined, it is seen that all three belong to different main headings. Moreover, according to the graph in Fig. 4 where all criteria are listed according to their weight values, it can be said that there is a serious break after these first three priority criteria. This situation shows a need to develop strategies for these three criteria in developing coastal cities. This situation shows that the qualities of a coastal city should be developed according to economic and urban growth and transportation criteria. Among all the criteria, “Intra-urban population density distribution” (0.05) was chosen as the least important criterion. After that, “Transportation from different countries to the city” (0.06) as a transportation criterion and “Traditional economic activities (fishing, agriculture, aquaculture)” (0.08) as an economic development criterion was chosen as the least important criterion (Fig. 4). This result shows that the necessary infrastructure for transportation for coastal access should be developed. According to these results, the sub-criteria of the three main criteria can be both the top priority criteria of a coastal city and the minor priority criteria on the other hand. Each main criterion (economic development, urban growth, and transportation) has an impact on the development of the coastal city qualities of Bursa, and that appropriate strategies should be determined according to the sub-criteria.

Fig. 4
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Sorting of coastal city criteria according to their weight values

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4 Discussion

Within the scope of this research, coastal city criteria were determined to evaluate the coastal city qualities of Bursa, which has a coast on the Marmara Sea, and the weight values ​​were determined by AHP, an MCDM method, and ranked according to their priorities. Since there is no research on the nature of the coastal city of the study area and there is no study on the digitization of the criteria in the studies of coastal cities in the world, the criteria were determined beforehand. Then they were digitized with AHP, which is a quantitative method. Survey results from experts and local people were used for digitization. This method was put forward with a participatory approach and was applied for the first time in Bursa and other coastal cities.

In research on coastal cities, some studies apply MCDM methods. In studies by Liu et al. (2019); Hadipour et al. (2020); Rocha et al. (2020); Sánchez-Lozano et al. (2020); Bagheri et al. (2021a, 2021b); Araujo and Dias (2021); Pathan et al. (2022) and Xiao et al. (2022), Fuzzy AHP, DELPHI, Entropy Weight Methodology, SWOT and TOPSIS methods were used, primarily AHP method. On the other hand, researches mainly consist of issues such as suitability for coastal use, flood and sea level rise, assessment of vulnerability in coastal cities, water quality, coastal tourism, flood risk assessment, and cultural protection in coastal areas. In this study, the AHP method, suitable for pairwise comparison according to the number of criteria determined, creates a holistic approach to evaluating coastal cities and eliminates this gap in the literature. It has an accuracy of less than 0.1 with a consistency ratio of 0.01 for the main criteria and 0.085, 0.016, and 0.092 for the sub-criteria. This method, which is used to evaluate the coastal quality of the city of Bursa by prioritizing the digitized criteria, will be a first in coastal surveys for Bursa.

Various studies have been conducted on the relationship between the city of Bursa and the coast. In their studies, Gündüz and Aytaç, (2013), Batman et al. (2019), Bulut and Murat, (2019), Polat and Arslan (2019), Akdeniz et al. (2020), Katip (2020), Değerli and Erbaş (2021) emphasized coastal architecture, water pollution, coastal vegetation, recreation potential and coastal land uses of Bursa. However, most of the studies are qualitative studies. However, in this study, the status of Bursa as a coastal city was questioned. The criteria that make up a coastal city were determined comprehensively by examining different literature and examples worldwide. In this context, the coastal city criteria of Bursa were listed as the main and lower coastal city criteria, and each criterion was prioritized by comparing the main and sub-criteria among themselves. In this way, for the first time, the coastal city criteria for Bursa and other cities worldwide were evaluated numerically according to their priorities. In this sense, the study will serve as a base for future studies of coastal cities and contribute to evaluating coastal city qualities of cities that have a coast to a sea or ocean.

In the studies of Demir et al. (2016), Özdemir Işik and Demir (2017), Demir and Atanur (2019), Asadpourian et al. (2020), Zorlu and Yilmaz (2020); Sahani (2021) emphasized that the pairwise comparison methods they used in their research increased the questionnaire questions. However, the number of criteria determined in this study led to the formation of an appropriate number of comparison questions for the AHP method. On the other hand, one of the advantages of the survey process is that the people have an excellent command of the subject in the surveys made with the local people. However, the process progressed slowly as access to the coastal areas of Bursa was limited during the survey process. Therefore, in future studies, survey studies will be easier and more effective by increasing the transportation possibilities from the city center to the coast.

Bursa is the fourth largest city contributing to the country’s economy with its port activities. The port activities, tourism activities, and the fact that the coastal areas of the city are suitable for agriculture are important criteria that increase the quality of the coastal city. (Cengiz et al., 2022; Dogan, 2013; Guneroglu, 2015; Kaypak, 2012). However, the fact that these coastal areas are far from the city center cannot integrate the coastal areas with the city of Bursa. Within the scope of this study, with the strategies proposed for the development of Bursa according to the coastal city criteria, it will be possible to increase the city’s coastal city qualities and strengthen the connection between the center of Bursa and the coastal region. In order to ensure this integrity, urban development and transportation activities should be developed, and economic activities should support these activities.

As a result of the research, the top three coastal city criteria with the highest priority were selected, respectively, “Location of the city center” (P3), “Transport to the inner city coast” (U2), and “Trade and port activities” (E1). Since Bursa is also a historical city, the place where the first urban development of Bursa started in history is in the Osmangazi district. However, in time, with the increase in the population of the city, Yildirim and Nilüfer districts also developed and formed the metropolitan area of ​​Bursa. The most important feature of these three districts is that they are connected to each other by different transportation lines, and the central transportation axis of the city passes between these districts. Therefore, urban integrity can be achieved by increasing the relations of the districts in the coastal part of Bursa with the city center. One crucial factor that provides the relationship between the city center and the coastal areas is the second priority criterion, the urban-to-coast transportation criterion. Due to the natural topography of Bursa, activities on transportation are limited. For this reason, a highway line for each coastal district provides transportation to the coast. However, increasing public transportation services over these lines will encourage transportation from the city center to the coast. At the same time, with the increase in transportation opportunities, the liveliness of the coast will increase, and it will be more related to the city center. Supporting these developments with the economic power coming from port activities can increase the dynamics of a coastal city. According to the results of the survey, The criteria of “Intra-urban population density distribution” (P2), “Transportation from different countries to the city” (U3), and “Traditional economic activities (fishing, agriculture, aquaculture)” (E3) were chosen as the least priority. Although it is of low value, considering these criteria in coastal cities can contribute to urban dynamics. The increase in urban population density in coastal areas may increase coastal activities. At the same time, the natural coastal structure, which is destroyed due to the pressure of urbanization, can be recovered through agriculture and aquaculture activities. It can increase the recognition of Bursa city as a coastal city by other countries by providing transportation to different geographies. Thus, it can contribute to the economic welfare of the city.

According to the AHP results, the three most and least priority criteria of the study area were selected from the three main criteria. According to this result, economic development, urban growth, and transportation should be considered together in all studies to be carried out within the scope of increasing the coastal city qualities of Bursa. However, physical and social interaction between the city center and the coast should be ensured. The transportation options of people living in the city center to the coast should be increased and facilitated. Tourism activities in coastal areas and cultural tourism activities in the city center should encourage each other. Planning should be done for coastal tourism, and the effect of tourism pressure on natural values ​​in the coastal region should be reduced. Land use in coastal areas should be planned considering the natural, cultural, and economic potentials of Bursa. For this purpose, an urban management plan should be prepared with the relevant ministries, local governments, private sector representatives, and stakeholders. The coastal management plan should be integrated into this management plan. The development of the city center and the coastal area should be planned together. Urban development and management of the city of Bursa should always be considered with the coastal factor in mind.

5 Conclusion

Coastal cities, typically defined as areas where both land and water dynamics coexist, are among the most striking and preferred settlements in the world. The fact that a city has a coast to the ocean or the sea is the main factor that shapes all urban dynamics and economic activities of that city. Most of the developed countries in the world are coastal cities. Coastal cities are distinguished from other cities by their interaction with different settlements in terms of their urban system, economic conditions, and transportation. The main objective of this study, conducted within the context of coastal cities, was to assess the holistic criteria for coastal cities, evaluate the coastal qualities of Bursa in accordance with these criteria, and suggest strategies to enhance the coastal city experience in Bursa accordingly. In this context, criteria suitable for the study area were determined by considering the characteristics of the coastal cities in the world. In the next stage, a survey was conducted with the participation of local people and experts, and the surveys were digitized using the AHP method, which is an MCDM method.

In coastal cities, coastal areas are important for urban life and economic activities. The development of the city is increasing thanks to the coastal areas, and therefore the coastal areas are the center of the city. That said, increasing the interaction of the center and coastal areas in coastal cities and supporting access to the coast can contribute to the development and economic prosperity of that city. For the city of Bursa, the criteria of “location of the city center,” “transport to the inner city coast,” and “trade and port activities” are listed according to the degree of importance among the coastal city criteria. Within the scope of this study, it is recommended to develop appropriate planning and design strategies by focusing on these criteria in order to increase the quality of the coastal city in Bursa. In this context, it shows that for a coastal city, decisions should be made by considering the economic, urban development, and transportation characteristics of that city together and paying attention to their connections with each other.

In order to increase the coastal city quality of Bursa, a holistic urban planning and design process should be established within the framework of legal regulations and criteria priorities. In this context, a participatory working process should be established with the relevant ministries, local administrations, experts, other stakeholders, and local people. As a result, the results and methodology of this study, which integrates the AHP method with a participatory approach and determines the coastal city criteria, and is conducted for the first time within the scope of Bursa, can set an exemplary model not only for Turkey but for all cities that have the potential to become coastal cities in the world.