Using Hydrological‐Biogeochemical Linkages to Elucidate Carbon Dynamics in Coastal Marshes Subject to Relative Sea Level Rise
Using Hydrological‐Biogeochemical Linkages to Elucidate Carbon Dynamics in Coastal Marshes Subject to Relative Sea Level Rise
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DOI：
10.1029/2019wr026302
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发表时间：
2020-02
影响因子：
5.4
通讯作者：
J. Guimond;Xuan Yu;A. Seyfferth;H. Michael
中科院分区：
文献类型：
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作者：
J. Guimond;Xuan Yu;A. Seyfferth;H. Michael
沿海沼泽是全球碳循环的重要组成部分，但我们对这些生态系统如何应对海平面上升（SLR）的理解是有限的。沿海沼泽水文根据海拔高度、与河道的距离和水力特性而变化，从而形成具有独特水位振荡模式的区域。这些区域影响生态和地球化学，并对应于碳积累速率的差异。这些物理-生态-地球化学联系使得水文模型能够用于预测沼泽地带性的变化，进而预测碳积累，以及SLR下的地下水-地表水交换。在这里，我们开发了一个校准的水文模型的特拉华州沿海沼泽地使用HydroGeoSphere。我们模拟了SLR，沉积物淤积和高地水文响应的三种情景，并量化了不同水文分区和地下水-地表水交换的空间覆盖范围的变化。结果表明，相对SLR减少沼泽面积，碳埋藏，和横向水通量。然而，变化的幅度与陆地地下水位响应以及相对SLR有关。在高地地下水位不随SLR变化的情况下，沼泽面积和碳积累的下降幅度比高地地下水位与SLR保持同步的情况下要小。相反，与高地地下水位保持在当前水平的情景相比，在高地地下水位上升等于SLR的情景中，横向水通量的减少最小化。这项研究强调了区域水文环境在沿海沼泽动态命运中的重要性。
Coastal marshes are an important component of the global carbon cycle, yet our understanding of how these ecosystems will respond to sea level rise (SLR) is limited. Coastal marsh hydrology varies based on elevation, distance from channel, and hydraulic properties, resulting in zones of unique water level oscillation patterns. These zones impact ecology and geochemistry and correspond to differences in carbon accumulation rates. These physical‐biogeochemical linkages enable use of a hydrological model to predict changes in marsh zonation, and in turn carbon accumulation, as well as groundwater‐surface water exchange under SLR. Here, we developed a calibrated hydrological model of a Delaware coastal marsh using HydroGeoSphere. We simulated three scenarios each of SLR, sediment accretion, and upland hydrologic response, and we quantified changes in the spatial coverage of different hydrologic zonations and groundwater‐surface water exchange. Results show that relative SLR reduces marsh area, carbon burial, and lateral water fluxes. However, the magnitudes of change are linked to the terrestrial groundwater table response as well as relative SLR. In scenarios where the upland water table does not change with SLR, the magnitude of decline in marsh area and carbon accumulation is reduced compared to scenarios where the upland water table keeps pace with SLR. In contrast, the reduction in lateral water flux is minimized in scenarios with an upland water table rise equal to SLR compared to scenarios where the upland water table is held at present‐day levels. This study highlights the importance of regional hydrologic setting in the fate of coastal marsh dynamics.