Interlinking Land Use Land Cover, Forest Biomass, and Air Quality in the Megacity Delhi, India

The rapid urbanization and population growth of megacities like Delhi, India, have led to significant changes in land use and land cover (LULC), adversely impacting environmental conditions, including forest biomass and air quality. This study inspects the complex relationships between LULC, forest biomass, and air pollution in Delhi, a city grappling with severe environmental degradation and some of the world’s highest air pollution levels. Landsat-8 satellite imagery was used to analyze LULC changes between 2021 and 2023, focusing on urbanization and its impact on vegetation cover. Air quality data were collected from Central Pollution Control Board (CPCB) monitoring stations across four locations in the city. Two high-traffic, sparsely vegetated zones (Anand Vihar and ITO) and two densely vegetated areas (Sri Aurobindo Marg and Mandir Marg) were selected for a comparative analysis. Additionally, forest biomass was quantified through direct sampling in two major green zones: Sanjay Van near Sri Aurobindo Marg and the Ridge Forest near Mandir Marg CPCB station. LULC analysis revealed a decline in vegetative cover in urban areas due to infrastructure expansion and the conversion of green spaces into residential and commercial zones. CPCB data over six years (2018 – 2023) indicated notable differences in air quality between densely vegetated and sparsely vegetated zones. PM_2.5 levels in high-traffic areas (Anand Vihar and ITO) were 24.20% and 23.19% higher than in densely vegetated areas (Sri Aurobindo Marg and Mandir Marg). Similarly, SO₂ concentrations were 1.52 times greater, and NH₃ levels were 1.69 times higher in regions with sparse vegetation. The biomass at Sanjay Van (112.57 tons) and the Ridge Forest (91.17 tons) significantly contributes to pollutant absorption, capturing considerable quantities of particulate matter (PM₁₀ and PM_2.5) and gaseous pollutants such as SO₂, NO_X, and NH₃, while also mitigating the impacts of land use and land cover changes by serving as essential green lungs in an urbanized environment. These forests collectively offer an estimated pollutant absorption capacity of many tons annually, underscoring their vital role in alleviating air pollution and preserving natural equilibrium amid fast urbanization. In brief, the study highlights the essential function of forested regions in Delhi in mitigating air pollution and promoting environmental sustainability.

Keywords: Air Quality; Vegetation; LULC; Biomass; Megacity