Assessing Spatio-Temporal Changes in the Ecological Livability Index (Case Study: Tabriz Metropolis )

AbstractA timely and comprehensive assessment of the urban ecological environment and its evolving trends is essential for urban planning, human habitation, and sustainable urban development. This research aimed to evaluate the spatio-temporal changes and conduct a comparative analysis of the ecological livability index for the years 2003 and 2023 in the metropolis of Tabriz. By utilizing Landsat and MODIS images, we prepared 5 key variables: Aerosol Optical Depth (AOD), Normalized Difference Vegetation Index (NDVI), Land Surface Temperature (LST), Normalized Difference Built-up Index (NDBI), and Normalized Water Difference Index (NWDI) to calculate the ecological livability index. Data analysis was conducted using ArcGIS Pro, Excel, and Google Earth Engine (GEE). The results derived from the CRITIC method for variable weighting indicated an upward trend in ecological livability. Specifically, the average ecological livability index in 2023 was 1.60 compared to 1.58 in 2003, reflecting an overall improvement in livability quality. Keywords: Ecological Livability, Spatio-Temporal Changes, Google Earth Engine (GEE), Remote Sensing & GIS, Tabriz Metropolis. IntroductionThe rapid pace of urbanization has resulted in over 50% of the global population now residing in urban areas. This surge has brought about numerous challenges, including declining health standards, increased social pressure, and environmental degradation. In recent years, various theories and approaches have emerged to address these urban challenges, particularly in metropolises. Concepts, such as sustainable development, sustainable urban development, eco-city initiatives, the green city framework, livability metrics, and urban sustainability and resilience, have been proposed to tackle these issues. These strategies necessitate a concerted effort to enhance urban conditions and safeguard city environments.The notion of urban ecological livability focuses on the quality of the environment surrounding local residents, encompassing location characteristics, environmental comfort, and community ecology. It is evident that residents aspire to thrive in a beautiful and healthy natural environment. Therefore, a key aspect of urban ecological livability is the creation of a livable urban ecological environment. Consequently, a timely and comprehensive assessment of the urban ecological environment and its changing trends is essential for effective urban planning, human habitation, and sustainable urban development.Tabriz, the capital of East Azarbaijan Province, is situated at 38° 88' north latitude and 46° 15' east longitude. Nestled between the Sahand Mountain Range to the south and the Aun Ibn Ali Mountain to the northwest, Tabriz ranks as one of the ten largest metropolises in Iran and is the largest city in the northwest with a population estimated at 1,558,693 in 2015. The aim of this research was to evaluate the quality of ecological livability in Tabriz for the years 2003 and 2023, utilizing remote sensing data to analyze spatial-temporal changes. Materials & MethodsThis research was categorized as applied research and employed descriptive-analytical methods. Variables were identified through a comprehensive literature review and data were collected using Landsat and MODIS satellite imagery, along with OpenStreetMap (OSM). Data processing was conducted using ArcGIS Pro, Excel, and Google Earth Engine (GEE). Initially, the Land Surface Temperature (LST), Normalized Difference Vegetation Index (NDVI), Normalized Difference Built-up Index (NDBI), and Aerosol Optical Depth (AOD) were generated within the GEE environment. The variable of Normalized Water Difference (NWD) was prepared using OSM. Following this, the CRITIC method was applied in Excel to calculate the weights of the variables and the final computation of the ecological livability index was carried out in ArcGIS Pro. Research FindingsThe results of the index calculation based on the weights of the variables revealed a consistent upward trend in ecological livability. Specifically, the quality of ecological livability in 2023 with an average value of 1.60 was higher than the average value of 1.58 recorded in 2003, indicating an overall improvement. In 2003, Regions 4, 6, and 1 exhibited the highest ecological livability scores, while Regions 3, 5, and 10 had the lowest. In contrast, by 2023, Regions 2, 1, and 4 emerged as the top performers in ecological livability, whereas Regions 10, 3, and 8 ranked at the bottom with the lowest scores. Discussion of Results & ConclusionThis study evaluated the ecological livability index of Tabriz metropolis to analyze spatial-temporal changes from 2003 to 2023. The Ecological Livability Index (ELI_i) was calculated using key variables derived from the research literature: Land Surface Temperature (LST), Normalized Difference Vegetation Index (NDVI), Normalized Difference Built-up Index (NDBI), Aerosol Optical Depth (AOD), and Normalized Water Difference (NWD), all assessed through a critical weighting model. The weights assigned to these variables were as follows: LST_i = 0.324, NDBI_i = 0.241, AOD_i = 0.215, NWD_i = 0.192, and NDVI_i = 0.028. Notably, the highest weight was attributed to land surface temperature, while the lowest was given to vegetation density.The results indicated that the quality of ecological livability across the regions maintained a consistent trend from 2003 to 2023. In 2003, areas in the northern and southern outskirts of the metropolis displayed low desirability values, whereas the central areas exhibited the highest livability scores. However, by 2023, the southern regions of Tabriz experienced the greatest concentration of unfavorable conditions. It is important to note that the final values of the ecological livability index could not be fully understood without considering the direct effects of the variables and their respective weights. For instance, the variable of LST_i = 0.324, which had the highest weight, showed a declining trend and was most concentrated in the central and southern parts of Tabriz. This decline corresponded with diminished vegetation growth in these areas and an increase in AOD, leading to unfavorable ecological livability conditions. These findings align with previous studies conducted by Liu et al. (2023), Bian et al. (2020), Hu and Xu (2018), and Yu et al. (2022).In conclusion, this study underscores the necessity of considering multiple factors and their weights when evaluating ecological livability. It offers valuable insights to the existing body of research on urban ecological assessment and planning, providing essential guidance for policymakers and urban planners aiming to enhance the livability of Tabriz metropolis and similar urban areas.