1. Introduction

The rapid and unplanned growth of metropolises in recent decades has been one of the most important factors in the destruction of vegetation cover and land use change. The metropolis of Mashhad, as the world's second most important religious metropolis and the main development hub in eastern Iran, has experienced accelerated physical and population growth in recent decades. Although this rapid development has aimed to address demographic and economic needs, the lack of integrated planning has led to extensive environmental consequences, with one of the most prominent and concerning being the destruction of vegetation cover and the reduction of green spaces.

The main issue of this research is to examine the trend and extent of this destruction and its direct connection with the city's physical expansion. Although governance challenges in urban environmental management (such as the dispersion of decision-making institutions, weak stakeholder participation, and the absence of a continuous monitoring system) are generally recognized, there is a lack of precise quantitative and spatial evidence regarding the impact of this development on the objective destruction of vegetation cover at the scale of Mashhad metropolis.

The central question is: To what extent and in what manner has the physical expansion of Mashhad metropolis during the period [1990-2024] caused the destruction of vegetation cover and the change of green land uses? This research specifically aims to utilize Remote Sensing (RS) and Geographic Information System (GIS) technologies to provide a quantitative and spatial picture of these changes, identify the areas that have experienced the most destruction, and accurately analyze the correlation between urban growth and the loss of vegetation cover.

Therefore, by addressing this knowledge gap, the present study not only provides a precise perspective on one of the most serious consequences of urban development in Mashhad but also supplies the necessary baseline data and spatial analyses for integrated planning and management, environmental protection, and moving towards sustainable development in this vital metropolis.



2. Methodology

This research, in terms of purpose, is classified as applied research with a descriptive-analytical nature, and methodologically, falls into the category of quantitative research. For data analysis, ENVI and ArcGIS software along with FLAASH, NDVI, NDBI algorithms and the combined ACO-SVM model were used for preprocessing, index extraction, and image classification.

3. Results

The results of the study indicate that over a 34-year period, the residential areas of Mashhad increased by 138% to 18,862 hectares, while rangelands and barren lands decreased by 47% to 9,847 hectares. Rainfed and irrigated agricultural lands also decreased by 43% and 36% respectively. These changes reflect an unsustainable development pattern and pose a serious threat to food security and environmental resilience. The validation with a Kappa coefficient of 0.91 confirms the accuracy of the research methodology.

4. Discussion

The analysis of land use changes in the Mashhad metropolis over a 34-year period (1990-2024) presents an alarming picture of unsustainable development patterns and their environmental consequences. According to the findings of this research, residential areas have experienced a remarkable 138% growth, expanding from 7,929 hectares to 18,862 hectares. This rapid urban expansion has imposed heavy costs on the region's environment and natural resources, resulting in a catastrophic decline in vegetation cover and natural areas. Rangelands and barren lands have decreased by 47%, from 18,629 hectares to 9,847 hectares. This has not only weakened the region's ecosystem resilience against climate change but has also seriously compromised its natural regenerative capacity.

Furthermore, the agricultural sector, as one of the main pillars of the region's food security and economy, has suffered significant damage. Rainfed agricultural lands have decreased by 43% to 1,671 hectares, while irrigated farmlands and orchards have been reduced by 36% to 1,588 hectares. This declining trend has not only led to adverse economic and social consequences but also indicates that the region's productive and ecological capacities have been overlooked in the urban development process.



5. Conclusion

The results of this study clearly demonstrate that the urban development pattern in the Mashhad metropolis over the past three decades has been based on the consumption of natural resources and the disregard for environmental considerations. This unsustainable trend has posed serious challenges to the long-term sustainability of the city and makes the need to revise urban development policies more evident than ever.

The results of this study clearly demonstrate that the urban development pattern in the Mashhad metropolis over the past three decades has been based on the consumption of natural resources and the disregard for environmental considerations. This unsustainable trend has posed serious challenges to the long-term sustainability of the city and makes the need to revise urban development policies more evident than ever.



Acknowledgments

This research did not receive any specific grant. From funding agencies in the public, commercial, or not-for-profit sectors.Acknowledgments

This research did not receive any specific grant. From funding agencies in the public, commercial, or not-for-profit sectors.Acknowledgments