Directions of land degradation in the greater Istanbul metropolitan area: A view from four decades

Abstract

In an era of dynamic urbanization, especially in densely populated regions such as the Greater Istanbul Metropolitan Area, land degradation (LD) is a widespread and multifaceted phenomenon. Hence, there is a need for monitoring LD to track the direction of urban sprawl and respond rationally. In this context, the purpose of this study was to investigate the magnitude and directions of LD in Istanbul from 1984 to 2022. The originality of the study lies in the development of the CAI_A index, which is a quantitative measure of the degree of anthropogenic impact. This study utilized Landsat 5 and Landsat 8 satellite imagery from 1984, 2002, and 2022, employing a maximum likelihood classification method to determine land cover and land use changes. The results show that the area of LD by anthropogenic activity has increased by an average of nearly 40 percentage points in each district of Istanbul over the past four decades, significantly impacting both natural and semi‐natural areas. Furthermore, a noteworthy observation was made regarding forests in the northern part of the study area, which demonstrated stability and resilience to LD. The results of the study are important for the urban environment because they facilitate a better understanding of the impact of human activities on mitigating LD in the context of climate change, among other things. Moreover, the results identify specific areas in need of targeted monitoring and remedial actions regarding LD.Research Highlights Istanbul's urbanization has been consistent since 1984. Urban expansion primarily contributes to agricultural land degradation. Land degradation clusters near settlements and on the southern coast. State forests are crucial for preserving natural areas and resisting degradation. Forest services are threatened by fragmented urban expansion.