GroMoPo Metadata for Heihe Basin coupled GW-LSM

Water and energy cycles interact, making these two processes closely related. Land surface models (LSMs) can describe the water and energy cycles on the land surface, but their description of the subsurface water processes is oversimplified, and lateral groundwater flow is ignored. Groundwater models (GWMs) describe the dynamic movement of the subsurface water well, but they cannot depict the physical mechanisms of the evapotranspiration (ET) process in detail. In this study, a coupled model of groundwater flow with a simple biosphere (GWSiB) is developed based on the full coupling of a typical land surface model (SiB2) and a 3-D variably saturated groundwater model (AquiferFlow). In this coupled model, the infiltration, ET and energy transfer are simulated by SiB2 using the soil moisture results from the groundwater flow model. The infiltration and ET results are applied iteratively to drive the groundwater flow model. After the coupled model is built, a sensitivity test is first performed, and the effect of the groundwater depth and the hydraulic conductivity parameters on the ET are analyzed. The coupled model is then validated using measurements from two stations located in shallow and deep groundwater depth zones. Finally, the coupled model is applied to data from the middle reach of the Heihe River basin in the northwest of China to test the regional simulation capabilities of the model.

水与能量循环相互作用，二者紧密关联。陆面模式（Land Surface Models, LSMs）能够刻画陆面的水热循环过程，但其对地下水文过程的描述过于简化，且忽略了侧向地下径流。地下水模型（Groundwater Models, GWMs）可较好地模拟地下水的动态运移过程，却无法详细刻画蒸散发（Evapotranspiration, ET）过程的物理机制。本研究基于典型陆面模式SiB2与三维变饱和地下水模型AquiferFlow的完全耦合，开发了地下水-简单生物圈耦合模型（GWSiB）。在该耦合模型中，入渗、蒸散发以及能量传输过程由SiB2结合地下水模型输出的土壤水分结果进行模拟；将入渗与蒸散发的模拟结果作为迭代驱动项，用于驱动地下水模型。耦合模型构建完成后，首先开展敏感性试验，分析地下水埋深与水力传导度参数对蒸散发的影响；随后利用分别位于浅埋深与深埋深地下水区域的两个站点的观测数据对耦合模型进行验证；最后将该耦合模型应用于中国西北黑河流域中游区域数据，以测试其区域模拟能力。