Assessment of risk of GHG emissions from Tehri hydropower reservoir, India

ABSTRACT

The hydropower reservoirs, considered as a green source of energy, are now found to emit significant quantities of greenhouse gas (GHG) to the atmosphere. This article attempts to predict the vulnerability of Tehri reservoir, India to GHG emissions using the GHG risk assessment tool (GRAT). The GRAT is verified with experimental GHG fluxes. The annual mean CO₂ fluxes from diffusion, bubbling, and degassing were 425.93 ± 122.50, 4.81 ± 1.33, and 7.01 ± 2.77 mg m⁻²d⁻¹, whereas CH₄ fluxes were 23.11 ± 7.08, 4.79 ± 1.08, and 7.41 ± 4.50 mg m⁻²d⁻¹, respectively, during 2011–12. The model found that Tehri reservoir emitted higher CO₂ and CH₄ (i.e., 790 mg m⁻²d⁻¹ and 64 mg m⁻²d⁻¹, respectively) in 2011, which came within vulnerability range causing more climate change impact. By the year 2015, it would scale down to medium risks necessitating no further assessment of GHG. Significant difference between predicted and experimental GHG emission are assessed, which may be due to insufficient data, spatial and temporal variations, decomposition of flooded biomass, limitation of GRAT model, and inadequate methodology. The study reveals that GHG emission from Tehri reservoir is less than predicted by the GRAT.

KeyWords:

• greenhouse gas (GHG)
• vulnerability
• emissions
• risk
• GRAT