Challenges with effective representations of heterogeneity in soil hydrology based on local water content measurements
Challenges with effective representations of heterogeneity in soil hydrology based on local water content measurements
复制标题
DOI：
10.1002/vzj2.20040
复制
发表时间：
2020-01
影响因子：
2.8
通讯作者：
H. H. Bauser-H.;Lukas Riedel;Daniel Berg;P. Troch;K. Roth
中科院分区：
文献类型：
--
作者：
H. H. Bauser-H.;Lukas Riedel;Daniel Berg;P. Troch;K. Roth
在田间尺度上描述土壤水分运动需要土壤水力学物质特性。这些不能直接测量，并表现出内在的多尺度异质性。通过反演模型或数据同化估计土壤水力特性需要测量系统的状态。然而，这些测量通常是稀缺的，不能解决土壤异质性，导致有效的材料特性有限的预测能力。在土壤剖面尺度的综合研究中，我们探索了基于位于一维和二维非均匀介质中的垂直剖面中的仅四个局部含水量测量来估计有效的简化一维表示的可能性。我们允许有效材料性质局部偏离，以考虑小尺度非均匀性对含水量测量的影响。在合成实验中，估计的简化一维表示法可以很好地预测土壤含水量和通量，但无法准确预测入渗锋的时间和大小。累积通量低于水含量的测量预测正确，即使在很短的时间尺度上，如果蒸发估计准确。然而，这被证明是具有挑战性的，如果局部蒸发通量以上的测量配置文件偏离强烈的平均蒸发通量的非均匀介质。一维估计导致土壤水力参数描述有效的材料特性，不同于真实的材料特性，以补偿缺失的非均匀性和二维流动的表示。
The description of soil water movement at the field scale requires soil hydraulic material properties. These cannot be measured directly and exhibit an intrinsic multiscale heterogeneity. The estimation of soil hydraulic properties through inverse modeling or data assimilation requires measurements of the state of the system. However, these measurements are typically scarce and do not resolve soil heterogeneity leading to effective material properties with limited predictive capabilities. In a synthetic study at the scale of soil profiles, we explore the possibility to estimate an effective reduced one‐dimensional representation based on only four local water content measurements in a vertical profile located in one‐ and two‐dimensional heterogeneous media. We allow the effective material properties to deviate locally to consider the impact of the small‐scale heterogeneity on the water content measurements. In the synthetic experiments, the estimated reduced one‐dimensional representations predict soil water content and fluxes sufficiently well but can fail to predict the accurate timing and magnitude of infiltration fronts. Cumulative fluxes below the water content measurements were predicted correctly even on short time scales, if evaporation was estimated accurately. However, this proved to be challenging if the local evaporation fluxes above the measurement profile deviated strongly from the average evaporation fluxes of the heterogeneous medium. The one‐dimensional estimation leads to soil hydraulic parameters describing effective material properties that differ from the true material properties to compensate the missing representation of heterogeneity and two‐dimensional flow.