In land surface models, the ability to simulate runoff is a good diagnostic for the hydrological cycle and other surface parameterizations; however, the partitioning of total runoff into surface and subsurface runoff shows considerable uncertainties. The interaction between soil moisture and groundwater plays an important role in simulating the surface and subsurface runoff. Specific yield (S_y) is widely used to calculate water table depths, in which the error comes mainly from uncertainty in determining the S_y value. This study developed a new soil moisture‐dependent model (SMD‐model) to improve the simulations of water table depths and partitioning total runoff into subsurface and surface components. The validations against observations and the Community Noah Land Surface Model with MultiParameterization Options (Noah‐MP) in three basins indicate that the SMD‐model can simulate a realistic and stable water table series, which shows the detailed variations of observed water tables, avoiding the uncertainties in determining S_y; and it can generate accurate proportions of surface and subsurface runoff. However, when S_y is used to calculate the water table depth, keeping other processes the same as in the SMD‐model, it produces a series of smoother and deeper water tables, and underestimates the proportion of subsurface runoff to total runoff by 24%–28%. Noah‐MP captures the overall variation of observed water tables and overestimates the proportion of subsurface runoff by 20%–33%. This study can provide relatively accurate estimations of water tables and surface and subsurface runoff, and benefit the study of land‐atmosphere interactions.

中文翻译：

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一种模拟土壤水分的水深，地表径流和地下径流比例的模型及其在流域尺度的验证

在地表模型中，模拟径流的能力是对水文循环和其他地表参数化的良好诊断。然而，将总径流划分为地表径流和地下径流的不确定性很大。土壤水分与地下水之间的相互作用在模拟地表径流和地下径流方面起着重要作用。比产率（S _y）被广泛用于计算地下水位深度，其中误差主要来自于确定S _y的不确定性价值。这项研究开发了一种新的土壤湿度依赖性模型（SMD模型），以改善地下水位深度的模拟并将总径流划分为地下和地表成分。在三个流域对观测值和具有多参数选项的社区诺亚陆面模型（Noah-MP）进行的验证表明，SMD模型可以模拟现实和稳定的地下水位序列，从而显示观测到的地下水位的详细变化，避免了确定S _y的不确定性; 它可以生成准确比例的地表和地下径流。但是，当S _y用于计算地下水位深度，保持其他过程与SMD模型中的相同，它会产生一系列更平滑和更深的地下水位，并且将地下径流在总径流中所占的比例低估了24％–28％。Noah-MP捕获了所观察到的地下水位的总体变化，并将地下径流的比例高估了20％–33％。这项研究可以提供相对准确的地下水位和地表及地下径流估算，并有利于研究陆地与大气之间的相互作用。