Evaluating the impact of urban sprawl on the urban ecological status using GIS and remote sensing from 2000 to 2021: a case study of Herat City, Afghanistan

Abstract

Urbanization often incurs environmental costs, as fertile agricultural and forested lands are converted into urban areas. Herat City is currently undergoing significant urban transformation. This research aims to assess the impact of urban sprawl on Herat City’s urban ecological status during 2000, 2013, and 2021, using GIS and remote sensing. The urban expansion intensity index was used to measure urban sprawl. The Mean Remote Sensing Ecological Index (MRSEI), integrating known granulation entropy (KGE) and comprehensive distance-based ranking (COBRA) algorithms, was utilized to evaluate urban ecological status. The random forest (RF) supervised machine learning-based algorithm was used to classify the study area into four categories (Built-up, Bare-land, Water, and Vegetation). Findings indicate rapid development from 2000 to 2013, followed by moderate expansion until 2021. Urban ecological quality degradation is observed in various directions over time, with the southeast consistently demonstrating excellent status. Interestingly, while good and excellent urban ecological status decreases over two decades, poor and very poor conditions improve. The research underscores an inverse relationship between urban expansion intensity and ecological status, highlighting the need for improved strategies to mitigate environmental decline. These findings will inform Afghan governmental bodies and international organizations, enabling them to better address resource consumption, ecological disruptions, social inequalities, and foster sustainable development.