Methane Emissions From The Littoral Zone Of Miyun Reservoir:Wetland-DNDC Modeling Approach Methane Emissions From The Littoral Zone Of Miyun Reservoir:Wetland-DNDC Modeling Approach

Hydropower, as renewable energy, has been considered as the key strategies in reducing emission of greenhouse gases. However, development of hydropower station through construction of dams has been raised global concerns over its environment impact on ecosystems. Meanwhile, due to its feature in submerging large area of farmland and forests, as well as its littoral zone water level fluctuation, it might be emit large volume of methane, and thus, its role in producing clean energy has been questioned. Thus, monitoring and assessment of greenhouse gases emission from reservoirs has become a hot issue in global climate change studies.The littoral zone of reservoir is believed to be a hotspot for methane (CH4) emissions, and the key questions are to understand the temporal and spatial variation of methane emission in the reservoir. This paper reports a study of CH4fluxes from the Miyun Reservoir near Beijing in China based on an integrated observational and modeling approach. CH4fluxes were measured at three sites with different water levels containing nine representative plant species. A process-based model, Wetland-DNDC, was tested against observations for its applicability in simulating CH4fluxes from the littoral zone of the water reservoir. The R2values, which showed correlation between the modeled and observed results, were0.89,0.81and0.49for the deep water, shallow water and seasonal flooded sites, respectively. The modeled data indicated that the observed CH4fluxes were mainly driven by water level fluctuations, soil temperature and soil organic matter content. It indicated that Wetland-DNDC model could be a new method for CH4fluxes from littoral zone with its spatial and temporal pattern. The modeled average annual flux from the littoral zone of Miyun Reservoir was15.1g CH4·m-2,which is similar with other studies in China.