Modeling Urban Expansion in Baghdad Governorate Using Spectral Indices

Abstract

This study aims to model and analyze urban expansion in Baghdad Governorate during the period (2013–2023) using remote sensing techniques and Geographic Information Systems (GIS) The analysis relies on spectral indices derived from Landsat 8 satellite imagery particularly the Normalized Difference Built-up Index (NDBI) and the Normalized Difference Vegetation Index (NDVI) . The study developed an analytical tool within the ArcGIS 10.8 environment to detect spectral changes using the Difference Image method . This tool enabled precise temporal comparison between satellite images and the reclassification of change results into five spatial categories : significant increase, slight increase, no change, slight decrease, and significant decrease, with area calculations conducted in square meters and square kilometers .   

The results revealed a noticeable increase in urban built-up areas, especially within dense and moderately dense classes, accompanied by a relative decline in certain medium vegetation cover classes. This indicates the continued urban sprawl at the expense of agricultural lands. Directional analyses further demonstrated that urban expansion followed multiple axes, most prominently toward the eastern and northern directions, while vegetation cover changes showed varying spatial trends.