水库温室气体净通量评估模型(G-res Tool)及在长江上游典型水库初步应用

目前准确量化温室气体排放量已成为气候变化研究和政策制定的关键.在IPCC水库温室气体净通量的概念性框架下，国际水电协会汇总分析了全球223座水库的CO₂和CH₄研究成果，构建了G-res Tool，其可以用于评估已建或待建水库在长时间尺度下的温室气体净通量.本文介绍了G-res Tool模型的基本原理与模型框架，利用模型内置数据库中所涉及的中国长江上游12座典型水库数据进行初步应用分析，12座水库温室气体净通量平均值为88.17 g CO₂e/（m²·a），在全球约7000座水库中所处水平为11.67%，处于低阈值范围.在水库温室气体净通量分析结果中，其他非相关人类活动产生的水库温室气体通量（UAS）在蓄水后总通量（Post）中所占比重远高于蓄水前温室气体通量（Pre）.长江上游水库蓄水后的CH₄和CO₂通量对于温室效应的贡献量相当.通过将G-res Tool模型蓄水后的温室气体通量评估结果和所涉及到的12座水库中已发表的数据对比分析发现，G-res Tool具有简便、适用面广等特点.但G-res Tool毕竟仍为经验性模型，其基本原理和模块设计上的内在缺陷在很大程度上限制了其应用范围并造成了一定的不确定性.对个案水库而言，长期跟踪观测与机理研究仍是未来减少水库温室气体净通量不确定性的关键.

The net GHG flux assessment model of reservoir(G-res Tool) and its application in reservoirs in upper reaches of Yangtze River in China

The identification and accurate quantification of greenhouse gas (GHG) have become a key challenge for scientists and policymakers working on climate change. Under the conceptual framework of the IPCC for the net GHG flux of reservoir, the International Hydropower Association analyzed the 223 reservoirs with CO₂ and CH₄ emissions data from the actual and past scientific literature to develop the G-res Tool, whether for an existing reservoir or planned reservoir project can provide an estimate of the net GHG flux. This paper introduces the basic principle and model framework of the G-res Tool model. We conducted the preliminary analysis of 12 typical reservoirs in the upper reaches of the Yangtze River in China, which were involved in the model built-in database. The average net flux of greenhouse gas in the reservoirs was 88.17 g CO₂e/(m²·a), which ranked 11.67% and was in the low threshold range among about 7000 reservoirs globally. Comparing the evaluation results of each part in the model, the contribution of emissions from the reservoir due to Unrelated Anthropogenic Sources (UAS) in the post-impoundment GHG balance from the catchment (Post) was much higher than in the pre-impoundment GHG balance from the catchment after introduction of a reservoir (Pre). Based on the post-impoundment GHG balance from the reservoirs in the upper reaches of the Yangtze River in China, it was estimated that CH₄ and CO₂ fluxes contributed quite to the greenhouse effect. After analysis and comparison of the published GHG flux data of the 12 reservoirs involved, G-res Tool was easy to operate and showed a wider application range. However, G-res Tool, as an empirical model, still has few internal defects in its basic principles and model design parts, which may cause some uncertainties and limit its application range. For case reservoirs, long-term follow-up observation and mechanism study are still the main methods to reduce the uncertainty of the net GHG flux assessment in the future.