Climate change vulnerability assessment of Karşıyaka, İzmir

Cities are among the systems with the highest vulnerability to climate change impacts. These impacts greatly affect the population and physical infrastructure of the cities. Vulnerability assessment plays a significant role in identifying vulnerable areas to climate change in the city and developing adaptation solutions for these areas. This study aimed to determine and map the vulnerability level of Karşıyaka, İzmir on watershed scale to climate change hazards, high temperature, flood and sea level rise by using indicator based approach. In this context an indicator set was developed for each vulnerability component, exposure, sensitivity and adaptive capacity, taking into account socio-economic, physical and ecological characteristics of the watershed, and then vulnerability was determined by calculations at the neighborhood scale. The results showed that urban areas in the inland had high exposure and sensitivity to. heat related hazards while coastal areas had high exposure and sensitivity to water related climate hazards. Almost two thirds of the residents lived under the risk of urban floods and extreme heat. The findings also indicated that sensitivity is lower on the inner parts of the study region where population density is low. Furthermore, coastal areas had the highest vulnerability even though they had high adaptive capacity. The findings are expected to be a useful tool for decision makers in increasing climate resilience and adaptive capacity.


Introduction
Coastal cities are highly vulnerable systems to climate change and its impacts because of their geographical and socio-economic characteristics.Approximately 11% of the world's population is located in low-lying coastal areas (Haasnoot et al. 2021) with intense economic activity and infrastructure.Although they already experience climate hazards such as storm surges and coastal floods, this exposure will increase in the future by sea level rise (Chang et al. 2015;Glavovic et al. 2022).Intergovernmental Panel on Climate Change (IPCC) indicates that global sea level will rise 0.63-1.01m by 2100 in the SSP5-8.5 GHG emissions scenario (IPCC 2023).This highlights the significant risks that coastal areas are facing.
Floods are one of the leading disasters that cause great damage and losses in coastal cities.According to Emergency Event Database EM-DAT in 2022, 57.1 million people were affected by floods all around the world.Floods in Pakistan, India, Bangladesh, China, Nigeria, South Africa, Brazil and Eastern Australia caused 5193 deaths and the economic damage was $35 billion (CRED 2023).Similarly, in 2023, floods caused serious damage and loss of life in many parts of the world (CRED 2024;Copernicus Climate Change Service 2024).
Heat waves are another climate risk that harms human and ecosystem health.Ballester et al. (2023) estimated that 61,672 people died from heat-related illnesses between May and September in 2022 in Europe.According to the World Meteorological Organization (WMO 2023), the average global temperature between 2023 and 2027 will be more than 1.5 C above the pre-industrial period with a 66% likelihood.
As climate change increases its impact and severity, it has become more necessary to take adaptation and mitigation measures.However, each city is affected differently by climate change.The vulnerability of cities to climate change and their adaptation needs vary according to their geographical location, development style, natural and cultural characteristics, and institutional and physical infrastructure (Chang et al. 2015;Kantamaneni 2016;Coşkun Hepcan 2022).Vulnerability assessment is important to identify potential risks and develop effective adaptation solutions to decrease climate change impacts and increase climate resilience (Percival and Teeuw 2019).Vulnerability analysis is applied in many cities such as Vancouver, New York, London around the world as it is significant stage for the city to take adaptation and mitigation measures (O'Hanlon 2020;McPhearson et al. 2024;ARUP 2024).
Like many countries, Türkiye is severely exposed to climate change impacts.İzmir is one of the important coastal cities where these effects are experienced.According to the Turkish State Meteorological Service, İzmir became the third city where the most meteorological disasters occurred, being mostly heavy rains and floods between 2010 and 2021 (MGM 2022).
Regarding adaptation to climate change in Türkiye, the Ministry of Environment, Urbanization and Climate Change carries out various projects throughout the country aimed at determining the climate change vulnerability of different sectors, and strengthening institutional capacity.In this context, 2024-2030 Climate Change Mitigation and Adaptation Strategy and Action Plans are recently published (MoEUCC 2024a, b).On a local scale, Green City Action Plan has been prepared for İzmir (IBB 2020).However, there is a need for studies to determine the vulnerability of cities to climate change, addressing different sectors.Therefore, this study was designed to fill this gap for the city of İzmir.
The objective of the current study was to assess the climate change vulnerability of one of the northern districts of İzmir, Karşıyaka by developing a set of indicators based on physical, ecological and socio-economic factors.The research question defined as: How to identify the most vulnerable to climate change areas in the city?

Study area
This study was conducted on the Kocadere-Ilıcadere watershed that covers Karşıyaka district in İzmir that is the 3rd largest and one of the most populated cities in Türkiye.The watershed covers 62.16 km 2 area and 40 neighborhoods on the north of the city with a population of 499,799 people (Fig. 1).
The watershed consists of low hills in the north and alluvial plains on the coast.Approximately 30% of the watershed is urbanized.The two rivers (Kocadere and Ilıcadere rivers) in the area flow in a natural course in rural areas while flows in a concrete channel in the urban landscape.This densely urbanized city settled on the coastal plain with low level green infrastructure (approximately 20%) (Yüksel 2022).The city has coastal parks along the coastline parallel to main transportation networks, roads and railway and residential area.
This region has a Mediterranean climate with a mean annual temperature of 17.9 ℃ and a mean annual precipitation of 709.9 mm (MGM 2023).According to historical records, Karşıyaka has experienced many climate related disasters.In 1995 historical flood occurred, causing many casualties and much property damage.Recent floods in 2021 and 2023 also greatly damaged the city's infrastructure and caused disruptions in urban life.As a coastal city, İzmir is faced with the threat of water damage due to storm surges and permanent sea level rise caused by climate change.Severe coastal floods in years between 2015 and 2023 greatly damaged the infrastructure and residential and commercial areas.Moreover, heat waves, which have increased in recent years, pose an increased threat to population and infrastructure.Since it is a region that is highly exposed to climate hazards, this study was conducted to determine the vulnerability level.

Methodology
In the current study geospatial, meteorological, hydrological and socio-economic data was used to determine climate hazards and calculate vulnerability (Table 1).
Fig. 1 The location of study area The methodology of the study consists of two phases: 1) Mapping of climate hazards, 2) Vulnerability assessment (Fig. 2).

Mapping of climate hazards
The climate hazards for the study area were determined to be high temperature and flood and sea level rise by evaluating the meteorological data given in Table 1.Identifying climate hazards is a necessary step in determining indicators in vulnerability assessment.

High temperature
Land surface temperature was calculated by following the steps (Sobrino 2004;Akyürek 2020;Mercan 2020) in Table 2 respectively with Landsat 8 satellite images within Arc-Map environment.TIR band 10 was used to determine the value of Top of Atmospheric (TOA) spectral radiance and Brightness Temperature (BT), while OLI spectral bands 4 and 5 were used to generate NDVI of the study area.A land surface temperature map showing the average of three months was generated by applying these processes to satellite images at three different times.The heat islands were determined by classifying the temperature values of the land surface temperature maps.

Sea level rise
Sea level rise has considered both storm surges and permanent sea level rise in the research.The permanent sea level rise value was adopted from the RCP 8.5 scenario as 0.64 m (IPCC 2014).Storm surge value was estimated to be 1.4 m based on earlier research (Gündüz and Tülger 2015).Consequently, the possible sea level rise for İzmir was determined to be 2.04 m.Sea level rise analysis was conducted in the spatial analyst tool in ArcGIS software by using DEM.

Flood
HecGeoRas and HecRas tools were used to estimate the flood risk for a 500 year flow in the watershed.The geometric data which includes the river center line, bank lines, flow paths and cross sections, was created to extract the physical characteristics of the rivers by using DEM data and HecGeoRas tools within ArcGIS.In HecRas the manning n values were assigned to each cross section line.The geometric data and flow data for the 500 year flow were entered to obtain the floodplain map for Kocadere and Ilıcadere streams in the watershed.

Vulnerability Assessment
The indicator-based approach was used to assess the vulnerability of the watershed.IPCC defines vulnerability as a function of exposure, sensitivity and adaptive capacity (IPCC 2014;IPCC 2022).With the indicator based approach, analysis steps are performed independently using different indicators for exposure, sensitivity and adaptive capacity.This method allows for ease of application and scientifically detailed analysis.
Vulnerability assessment was carried out in two steps such as defining indicators and calculating vulnerability.

Indicators
In the first step of the vulnerability assessment, indicators for exposure, sensitivity and adaptive capacity of the study area for climate hazards were determined based on previous studies on vulnerability assessment (Prasad et al. 2008;Swart et al. 2012;Çobanyılmaz and Yüksel 2013;Tapia et al. 2017;Bucak et al. 2021) by considering data availability and measurability for the study area.Detailed information about the indicators is given in Table 3 and the following section.'Exposure is the presence of people, livelihoods, species or ecosystems, environmental functions, services, and resources, infrastructure, or economic, social, or cultural assets in places and settings that could be adversely affected by climate change' (IPCC 2014).In the exposure analysis, it was evaluated whether the population, coastal areas, built up areas and transportation were affected by high temperature, flood and sea level rise (Table 3).
'Sensitivity refers to the degree to which a system is positively or negatively affected by climate variability or change' (IPCC 2014).Sensitivity indicators were categorized into five, as vulnerable population, coastal areas, built up areas, health and transportation (Table 3).
'Adaptive capacity is the ability of systems, institutions, people and other organisms to adapt to potential damage, take advantage of opportunities or respond consequences' (IPCC 2014).Vulnerability is high when adaptive capacity is low and sensitivity is high.Adaptive capacity indicators were categorized into four group as institutional, social, gray infrastructure and blue-green infrastructure capacity (Table 3).

Blue-green infrastructure capacity
The percentage of green infrastructure in the neighborhood The percentage of blue infrastructure in the neighborhood 1: < %25 2:%25-%50 3: > %50
The weighting was made within the scope of the expert judgment of the researchers, taking into account the scientific studies on vulnerability assessment (GIZ 2017; Bucak et al. 2021).The determined indicator and weight values were digitized using equations and mapped within GIS.

Climate hazards
The climate hazards maps of watershed for high temperature, sea level rise and flood are shown in Fig. 2.
In the land surface temperature map (Fig. 3a), the highest value is 43.6℃ and the lowest value is 26.3℃.The highest temperature values observed in the neighborhoods with the numbers of 32, 33, 26 and 25 which are located in the east of the watershed.The lowest values observed on the outer periphery of the neighborhoods (35, 39 and 40) located in the north.Additionally, lower average values were observed on the coastal line and some neighborhoods, namely 2, 3 and 4 located on coastline compared to other parts of the study area.
Sea level rise risk map showed that all neighborhoods along the coastline were exposed to sea level rise.Some of these neighborhoods were completely affected (1, 2, 7 and 8) while the others were partly affected (3, 4, 5, 6, 11 and 20) (Fig. 3b).It is calculated that the rising water overflows 300-1000 m inland from the coast, affecting an area of approximately 3.3 km 2 and 160,000 residents and their livelihoods, directly.
The results of flood risk analysis indicated that the neighborhoods located on the floodplains of two rivers (3, 13, 18, 8, 19, 20, 26, 23, and 28) were most severely affected (Fig. 3c).The floodplain on the left covers 2.43 km 2 urban area with 188,552 residents.The relatively small floodplain on the right covers 0.88 km 2 area with 86,882 residents.

Vulnerability
Exposure map showed that high exposure was found in neighborhoods located in the coastline (1, 2, 3, 4, 5, 6, 7, 8, 9 and 11) with an area 5.1 km 2 .Only two neighborhoods, namely, 10 and 14, had moderate exposure, while there was low exposure in the rest of the neighborhoods in the study area (Fig. 4a).

High temperature
The study region was generally exposed to high temperature and intense heat islands in some regions.The neighborhoods (24, 26, 27, 28, 30, 32, 33, 34 and 40) in the western and northeastern parts of the study where heat islands were observed.These neighborhoods, with little or no vegetation cover and rocky terrain, were where heat islands were observed.
Furthermore, it has been determined that high temperatures between 35 ℃ and 38 ℃ affect the highly urbanized neighborhoods located in the core of the watershed.These neighborhoods mainly consist of residential areas where the construction is dense and irregular with poor green infrastructure components.
On the other hand low temperatures and cool islands have been observed in some regions of the study area.Lower temperatures were in natural areas with dense vegetation on the northern edge of the watershed and in coastal areas.It has been observed that the larger urban green areas such as the cemetery and natural woodland patches in neighborhoods 24 and 35 formed cool islands and reduce the temperature around them.Similarly, the coastal parks along the coastline formed distinct cool islands with the influence of the sea.
These findings are consistent with the results of the previous studies such as Şentürk and Çubukçu (2022) and Yüksel and Coşkun Hepcan (2023).The heat waves experienced in the last few years, especially in 2022 and 2023 (MGM 2023), have had negative effects on city residents and urban life.It poses a significant health threat, especially for the vulnerable groups such as elderly, children and people with chronic diseases.

Flood
The floodplain model for 500 years exposed the fact that the flood impact area of the streams enclosed in a concrete canal in the city center is greater than the streams flowing in their natural beds on the outer periphery of the watershed.
Physical and environmental characteristics of the stream such as bed width, ground structure, vegetation cover around and inside the stream, are the factors that affect the water holding capacity of the stream.The stream in its natural form regulates the flow rate and ensures water retention with its sand-soil ground and surrounding vegetation.On the other hand the rivers in the city center cannot hold the rainwater due to its impermeable surface, resulting causing floods.
The 500-year flood model obtained by TOB (2019) for Kocadere and Ilıcadere streams is similar to the findings of this study.The results also indicate that most of the areas inundated were also affected by historical flood events.

Sea level rise
Sea level rise analysis showed that all neighborhoods along the coastline are greatly affected by this hazard.According to these results, incoming water could move 300-1000 m inland in the residential and industrial areas on the lowlands.As a result, more than 160,000 people, in built up areas and transportation lines would be affected.This output is also consistent with the results of the research conducted by Dalfes and Avcı (2023).
Considering the historical climatic events, coastal flooding has occurred in the watershed and similar areas have been damaged, consistent with the findings of this study.Therefore, rising sea level is one of the climate risks that require urgent measures.In 2020 the Karşıyaka coastal restoration carried out with gray solutions predominantly included graded seating areas, playgrounds and open areas with sparse vegetation.Increasing the capacity of this coastal park by building Nature-based Solutions such as water retention areas will increase coastal resilience for the possible scenario of storm surge and sea level rise.

Exposure
The watershed is exposed to different climatic hazards at different intensities.Neighborhoods located in the coastal area have higher exposure compared to other parts of the watershed as they are affected by sea level rise.It is clear that around 5.1 km 2 coastal area with 149,096 residents are at great risk of exposure.That means 33% of the city residents and 8.2% of the urban landscape are exposed climate related hazards.
Additionally, the main transportation lines of the city such as roads and train lines are located along the coastline.High surface temperatures result in deformation on the surface of asphalt that increases the need for repair.On the other hand extreme precipitation and therefore urban floods are the main problems for these infrastructures.The vehicle and train lines are affected by the floods that disrupt traffic and limit the mobility of the city dwellers.
The climate change models for 2050 and 2100 for İzmir predicted that the study area will experience 1.5 ℃ temperature increase, as well as increased extreme rainfall (Berberoğlu et al. 2019).In this scenario major risks arise for the urban ecosystem, public health and infrastructure.While high temperatures will cause health problems for the especially vulnerable groups such as elderly and chronically ill, extreme rainfalls will cause damage to urban infrastructure and properties, increasing the risk of injuries and deaths.Consequently, it is clear that adaptation measures should be taken in the study region.

Sensitivity
Sensitivity analysis indicated that 73% of the population live in the moderately sensitive zone, which accounts for approximately 23% of the watershed.
Neighborhoods located on coastal lowlands have higher sensitivity than upland neighborhoods.One of the main reasons of high sensitivity on the coastal land is the high percentage of built areas and transportation lines that exposed to climate hazards.Furthermore, the population rate of vulnerable group (65 years or older) was high in these neighborhoods (TÜİK 2020).Additionally, the historical coastline of the city was changed because of the sea embankment in 1980s.Therefore, these areas are more sensitive to sea level rise and urban flood.There is always the risk that those parts of the coasts will disappear.
On the other hand low density urbanization and low population are the major factors for the low sensitivity.Neighborhoods with low sensitivity, the regions in the north of the watershed, are generally natural areas with dense vegetation cover.In relation to this another reason of the high sensitivity of the coastal neighborhoods is the high construction rate and low amount of green space.Air pollution was another indicator for sensitivity that directly affects human health in the city.Annual air quality monitoring records showed that the PM10 level in the region can exceed the limits determined by World Health Organization.Air pollution is mainly caused by emissions from the city and it could also be associated with high temperatures.There are studies indicated that high temperature can cause air quality to deteriorate (Papanastasiou et al. 2014;Analitis et al. 2014).Therefore, increasing the urban tree canopy will provide mutual benefit by removing pollutants and creating a microclimate effect in the watershed.

Adaptive capacity
Adaptive capacity of the watershed showed different patterns in the neighborhoods.Results indicated that 54% had high, 7% had moderate and 39% had low adaptive capacity of the watershed.The neighborhoods with the high and moderate adaptive capacity were clustered in the coastal areas, although these areas have high exposure and sensitivity.This outcome is related to the indicators used for calculating adaptive capacity.
Adaptive capacity was evaluated based on institutional, social, gray infrastructure and blue-green infrastructure capacity.The most effective values in increasing the adaptive capacity of the study area were institutional and social capacities, while gray and bluegreen infrastructure capacities were very low.
The institutional capacity of the study was considerably high because of the actions of the municipalities such as the existence of the Sustainable Energy and Climate Action Plan, memberships to national and international city networks, awareness and capacity building projects.These current plans and capacity building projects mostly focused on mitigation such as waste management, sustainable energy and carbon emission rather than adaptation.The watershed received high scores from the social capacity because of the high level of education and socio-economic development, and the presence of environment-oriented associations.
However, the findings of this study showed that the existing gray and blue-green infrastructure of the watershed is mostly insufficient for disaster risk reduction for climate hazards.When urban transportation infrastructure is considered, the existence of rail systems and bicycle paths and the use of electric vehicles in public buses are effective measures for mitigation.However, transportation infrastructure that is the most affected by climate hazards, especially urban floods, need to be improved within the scope of adaptation.To increase the climate resilience, hybrid (green and gray) and nature-based solutions should be integrated into this infrastructure.Furthermore, using a combination of gray and green solutions for floods, especially on the coastline and river banks, will be effective in reducing the disaster risk in these regions.The recently implemented coastal park was effective in increasing the adaptive capacity value of the coastal neighborhoods.This park includes gray solutions such as sea walls to block sea level rise.But the results showed that the existing measures are not enough to protect the city from sea level rise.The adequacy and effectiveness of the practices should be evaluated during storm surges and coastal flooding and affected areas should be developed.
One of the most significant factors in reducing the effects of climate change and increasing resilience is the capacity of the blue-green infrastructure.In this study, it is clear that the existing blue-green infrastructure is not effective enough to reduce the effects of climate change.The adaptive capacity is very low due to the lack of blue and green infrastructure components and the connections with each other in the watershed.

Vulnerability
Vulnerability analysis revealed that one third of the study region, mostly coastal neighborhoods, were highly vulnerable to climate change.
It is clear that these areas require immediate action to increase climate resilience.These neighborhoods experienced high exposure and sensitivity to climate hazards, especially sea level rise and floods.Even though the overall adaptive capacity of these neighborhoods is higher than other areas, they are lacking in terms of blue-green infrastructure capacity which plays a significant role in reducing vulnerability.
The findings emphasized that vulnerability is directly related to sensitivity and adaptive capacity.In the vulnerability map, it was observed that vulnerability was high in areas with high sensitivity and low adaptive capacity.These findings are consistent with the research that focused for the metropolitan area of İzmir (Sılaydın Aydın et al. 2017).
In this study, indicator-based approach was used to be determined factors such as socioeconomic, institutional and geographical characteristics of the study area.This approach has been widely used to define the vulnerabilities of urban areas by given equal or different weights to indicators (Rocha et al. 2020;Rizzo et al. 2020;Hadipour et al. 2020).In this study, each indicator was weighted according to its importance to vulnerability components based on expert judgment.
One of the limitations of this research was to use limited indicators for the analysis due to the lack of socio-economic and geospatial data.For instance, the chronically ill and disabled population could not be included in the vulnerable population category.Also, the data for the capacity of drainage channels in the city could not be reached.

Conclusion
This study determined the vulnerability of Kocadere-Ilıcadere watershed to extreme climate events such as high temperature, flood and sea level rise, using indicator-based approach.Indicators were developed for each vulnerability component considering physical, ecological and socio-economic features of the study area.Results showed that the vulnerability decreased from the coast to inland areas in the watershed.Coastal neighborhoods had especially high vulnerability.
Therefore, it is necessary to take adaptation measures to increase climate resilience in these areas.Although the adaptive capacity of the watershed is at a certain level, it is inadequate in solutions to sea level rise and floods.As a matter of fact, the coastal park along the coastline has high potential for improving adaptive capacity.Existing gray solutions can be integrated with nature based solutions to increase climate resilience against flood risk and also reduce the effects of high temperatures.Moreover, Provincial and district Climate Action Plans should be reviewed and rearranged taking into account these and similar vulnerability studies, and actions should be taken for areas that need to be prioritized and completed.
In conclusion, the outcomes of this vulnerability assessment provide valuable data for decision-makers, planners and landscape architects to take actions for highly vulnerable areas.Especially vulnerability maps highlight the areas that need to be prioritized to combat climate change.By taking on some of the critical measures, it is possible to reduce exposure and sensitivity to potential climate hazards and to achieve Sustainable Development Goals (11, 13 and 15) in the city.

Fig. 2
Fig. 2 Methodology of the study

Table 3
Vulnerability indicators (adapted from GIZ 2017; Bucak et al. 2021) The percentage of vulnerable population (children and adults 65 +) in the neighborhood 2 days during the year when PM10 amount is above the limits 1: < 35 days 3: ≥ 35 days 0,9 Transportation The percentage of transportation lines affected by climate hazards in the neighborhood 1

Table 1
Dataset used in this study

Table 4
Scale of indicator and