Impact of Land Use Changes during Agricultural Cycles on AOD Trends over the Indo-Gangetic Plain during Last Two Decades

Rapid urbanization and industrialization lead to significant changes in land use and land cover (LULC), particularly in agricultural activities over the Indo-Gangetic Plain (IGP), which in turn impacts the distribution of aerosol loading. In the present study, climatological and spatio-temporal trends of aerosol optical depth (AOD) and aerosol sources are investigated over the IGP region from 2001 to 2022. Climatological analysis of the AOD over the upper, central, and lower IGP regions was conducted using satellite-based MODIS data. LULC analysis over the IGP region during the study period showed a significant increase in crop land and built-up area, mainly replacing the vegetation. It is hypothesized that changes in LULC patterns, especially the expansion of cropland and crop residue burning (CRB), are major drivers of aerosol trends. The results reveal significant AOD increases, particularly in the lower IGP, which experienced extensive vegetation loss replaced by cropland, intensifying CRB and aerosol emissions. In contrast, the upper IGP exhibited reduced CRB activity and even declining AOD trends during the second half of the study period (2012–2022), indicating improved air quality. The findings highlight a direct relationship between LULC changes, CRB, and AOD trends, emphasizing the need for sustainable agricultural practices and emission control measures to mitigate aerosol pollution and improve air quality across the IGP.