Estimating CO2 and CH4 fluxes from reservoirs: Model development and site-level study

A research team from the School of Earth System Science of Tianjin University developed a high-resolution, dynamic model for simulating reservoir GHG emissions is essential for improving estimation accuracy. This study developed and integrated a Carbon Greenhouse Gas (C-GHG) module (including CO₂ and CH₄) into the Environmental Fluid Dynamics Code (EFDC).

This module simulates the spatiotemporal variations of CO₂ and CH₄ in reservoirs while comprehensively accounting for key physical and biogeochemical processes governing their production, transport, and emission. To evaluate its performance, the study applied the model to a typical reservoir in southwestern China, simulating the dynamics of CO₂ and CH₄ emissions and assessing their global warming potential.

The results demonstrate that the model effectively captures the dynamic variations of CO₂ and CH₄ at different monitoring points throughout the year and accurately represents their spatiotemporal distribution patterns. The study reveals that tributary regions, particularly shallow areas, serve as hotspots for C-GHG emissions. Seasonally, the reservoir functions as a CO₂ source during autumn and winter but may act as a CO₂ sink in spring and summer. In contrast, CH₄ remains a net emitter year-round. Over a 100-year timescale, CH₄ accounts for 81.5% of the reservoir’s total global warming potential (GWP), with CH₄ ebullition contributing 66.5% of total CH₄ emissions. Overall, the model developed in this study provides a robust tool for quantitatively assessing the spatiotemporal dynamics of reservoir C-GHG emissions and underscores the critical role of CH₄ ebullition in tributary regions. These findings suggest that current global estimates of reservoir GHG emissions may be significantly underestimated.

The research has been published in Journal of Hydrology as the paper “Estimating CO₂ and CH₄ fluxes from reservoirs: Model development and site-level study”. Weiwei Shi is the first author of this paper, with Prof. Zhifeng Yan as the corresponding author. This work was supported by the National Natural Science Foundation of China and the National Key R&D Program.

By School of Earth System Science

Editor: Sun Xiaofang