Post-earthquake urban reconstruction, land use, and tropospheric NO₂ exposure in Malatya, Türkiye

Abstract

Land-use decisions made during post-disaster reconstruction can reshape transport systems, built-up environments, and the spatial distribution of environmental exposures. However, these relationships remain insufficiently examined in earthquake-affected cities. This study evaluates the temporal and spatial patterns of tropospheric nitrogen dioxide (NO₂) in Malatya, Türkiye, during 2019–2025 and compares the 2019–2022 baseline with the 2023–2025 reconstruction period. Sentinel-5P TROPOMI observations were integrated with land use/land cover, road density, elevation, NDVI, and NDBI within a common spatial framework comprising 108,626 pixel-year observations. Tropospheric NO₂ was modelled using XGBoost, variable contributions were interpreted through SHAP, and spatial dependence was assessed using Global Moran’s I. High NO₂ levels were consistently concentrated along the Battalgazi-Yeşilyurt urban axis, where dense road networks, artificial surfaces, and intensive urban functions overlap, whereas lower values were observed in higher-elevation and lower-density areas. Land use/land cover had the greatest gain-based contribution to the model, while elevation exerted a stronger influence on pixel-level predictions. The model showed moderate predictive performance on the holdout test set (R2 = 0.5941, RMSE = 2.816 μmol m−2, and MAE = 1.865 μmol m−2). Annual Global Moran’s I values ranged from 0.9893 to 0.9922 (p = 0.001), indicating strong spatial clustering of tropospheric NO₂ throughout the study period. The reconstruction period was characterized by a more fragmented and spatially heterogeneous NO₂ pattern rather than a uniform province-wide increase. These findings suggest that changing transport flows, built-up development, topographic controls, and post-disaster spatial reorganization may jointly differentiate environmental exposure conditions. The study provides interpretable spatial evidence for health-sensitive land-use planning, air-quality monitoring, and post-disaster urban management.