Sensitivity of Global Hydrological Simulations to Groundwater Capillary Flux Parameterizations
Sensitivity of Global Hydrological Simulations to Groundwater Capillary Flux Parameterizations
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DOI：
10.1029/2018wr023434
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发表时间：
2019-01
影响因子：
5.4
通讯作者：
Sujan Koirala;Hyungjun Kim;Y. Hirabayashi;S. Kanae;T. Oki
中科院分区：
文献类型：
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作者：
Sujan Koirala;Hyungjun Kim;Y. Hirabayashi;S. Kanae;T. Oki
全球陆地表面和水文模型，用于量化地下水（GW）动态对陆地表面水文的影响，不同的GW毛管通量和GW和非饱和土柱之间的水分通量交换深度（相互作用深度）的参数化。在这项研究中，我们证明了毛细血管通量的参数化显著影响GW支持的ET（±15%）和GW补给（±25%）的大小。最大的敏感性与一个强大的依赖性的毛细通量参数化对地下水位深度（WTD）与土壤水力特性的进一步控制。在浅WTD条件下，较细的土壤显示出较大的GW-支持ET参数化，仅取决于WTD。此外，与相互作用深度随WTD在空间和时间上变化的模拟相比，GW支持的ET在模拟中使用的相互作用深度每增加1米减少7-13%。径流，土壤水分和WTD的模拟更敏感的参数化和相互作用深度的差异。此外，这些敏感性在空间和时间上都有很大差异。对基于观测的数据和先前的建模模拟的评估表明，在具有大GW支持的ET的区域中，具有毛细通量的模拟比没有毛细通量的模拟表现得更好。我们一致认为，毛管通量在全球水文模拟中有着不可忽视的影响。但是，水文通量和存储的敏感性的时空变化表明，不同的GW毛细通量的参数化也可能导致全球水文模拟和随后的水资源评估的实质性的不确定性。
Global land surface and hydrologic models, used to quantify the influence of groundwater (GW) dynamics on land surface hydrology, vary in parameterizations of the GW capillary flux and depth of moisture flux exchange between GW and unsaturated soil column (interaction depth). In this study, we demonstrate that the parameterization of capillary flux significantly affects the magnitude of GW‐supported ET (±15%) and GW recharge (±25%). The largest sensitivities are associated with a strong dependence of the capillary flux parameterization on water table depth (WTD) with further controls by soil hydraulic properties. Under shallow WTD condition, the finer soils show a larger GW‐supported ET for parameterization that depends only on WTD. Further, GW‐supported ET reduces by 7–13% per meter increase in interaction depth used in simulation compared to simulation in which the interaction depth varies in space and time with WTD. The simulations of runoff, soil moisture, and WTD are even more sensitive to the difference in parameterization and interaction depth. Moreover, these sensitivities vary largely in both space and time. Evaluations against observation‐based data and previous modeling simulations reveal that simulations with capillary flux perform better than that the one without it in regions with large GW‐supported ET. We concur that capillary flux has a large and nonnegligible influence in global hydrologic simulation. But, the spatiotemporal variabilities of sensitivities of hydrological fluxes and storages demonstrate that different parameterization of GW capillary flux may also lead to a substantial uncertainty in global hydrologic simulations and subsequent water resources assessments.