Field validation of predictive model for greenhouse gas emissions from unsanitary landfill

Unsanitary landfill practices in developing countries like Bangladesh significantly contribute to global greenhouse gas (GHG) emissions, exacerbating climate change impacts. GHG estimation and measurement often rely on approximate input data, overlooking waste height variations and leading to emission inconsistencies. This study employs LandGEM-V-3.03, integrating actual landfill waste deposition from truck scale monitoring, waste generation and collection trends, and a precisely estimated landfill lifespan for improved assessment. Additionally, a static closed flux chamber was used to measure CH 4 and CO 2 across four seasons at varying waste heights, which were precisely assessed using a LiDAR-based Digital Terrain Model (DTM). The study also examined emission correlations with temperature and humidity. Results show a sharp increase in methane emissions, peaking at 5.8 Gg/year in 2025, driven by waste-damping rates. Humidity exhibits a stronger correlation with methane emissions (R 2 = 0.998, 0.944 for model and field) and is statistically significant (p < 0.05), unlike temperature. A similar trend was observed for CO 2 , where emissions were significantly higher than CH 4 (CH 4 -to-CO 2 ratio 0.25 to 0.57) due to both aerobic and anaerobic production modes. Field measurements underestimated emissions by 5–20%, with the highest emissions and discrepancies occurring during monsoon. Waste height significantly influenced CH 4 emissions (R 2 = 0.82, p = 0.00), increasing at 2.88 mg/m 2 /min per meter, while CO 2 emissions showed a weaker, statistically insignificant correlation (R 2 = 0.4, p > 0.05). The study highlights the critical need for improved landfill management practices and precise emission monitoring for effective GHG mitigation. • Methane emissions may hit 5.8 Gg/year by 2025 as waste loads increase. • Higher humidity strongly boosts methane release from landfills. • Taller waste body release more methane—2.88 mg/m 2 /min per meter. • GHG emissions are often undercounted, especially during the monsoon. • Carbon dioxide dominates landfill gases, with CH 4 :CO 2 as low as 0.25.