Greenhouse gas emissions and footprint analysis of multi-purpose dam reservoirs in temperate climates: Case study from South Korea

Globally, multipurpose dam reservoirs (MDRs) provide diverse socio-economic services, but their net greenhouse gas (GHG) footprint remains uncertain in South Korea. To address this issue, this study quantified GHG emissions from seven temperate MDRs using the G-res Tool and compared the results with IPCC 2006 and 2019 Tier-1 methods. The G-res Tool estimated net emissions ranged from 255 to 509 g CO 2 eq./m 2 /yr (average 325), which were 36 % and 82 % higher than IPCC 2019 and 2006 estimates, respectively. This difference arises mainly because the G-res Tool incorporates forest carbon sinks prior to impoundment. Flux partitioning analysis indicated that surface CO 2 diffusion represented the largest contribution (133 g CO 2 eq./m 2 /yr), followed by CH 4 diffusion (65), degassing (30), and bubbling (14). Estimated emissions per kilowatt-hour of electricity produced ranged from 17.0 to 61.9 g CO 2 -eq./kWh (average 36.3), generally comparable to ranges (6.8–57.6 g CO 2 -eq./kWh) reported for temperate-region reservoirs worldwide, though one site exceeded upper range. In line with prior studies, an inverse pattern was observed between power density (W/m 2 ) and emission intensity. Contributions from unrelated anthropogenic sources (UAS), emissions not attributable to the dam itself but to upstream human activity, ranged from 15.2 % to 33.9 %. Sensitivity analysis revealed a significant positive association between total phosphorus levels and GHG output. These results underscore the importance of linking reservoir GHG assessments with land-use planning and water quality control. The study provides practical guidance for dam managers and policymakers seeking to improve operational performance while minimizing climate impacts through integrated upstream-downstream management strategies. • Study assessed GHG emissions of seven Korean multipurpose dam reservoirs (MDRs). • G-res Tool showed higher emissions than that in IPCC guidelines due to carbon sink loss. • CO 2 diffusion was the largest carbon flux, followed by CH 4 diffusion and degassing. • Low power density MDRs showed prominent GHG emissions; intensity varied by factors. • Unrelated anthropogenic sources contributed 15.2–33.9 % of net GHG footprint.