Sensitivity of Simulated Mountain Block Hydrology to Subsurface Conceptualization
Sensitivity of Simulated Mountain Block Hydrology to Subsurface Conceptualization
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DOI：
10.1029/2020wr027714
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发表时间：
2020-10
影响因子：
5.4
通讯作者：
G. Rapp;L. Condon;K. Markovich
中科院分区：
文献类型：
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作者：
G. Rapp;L. Condon;K. Markovich
山地块体系统对水资源至关重要，近几十年来已进行了大量研究和建模。然而，由于缺乏现场数据，在模型如何表示山块地下几乎没有一致性。虽然有大量的地下异质性的研究，很少有研究评估的影响，共同的概念选择建模在山区系统模拟水文。在这里，我们使用六种常见的山体地下概念模型模拟半理想化水源集水区的水文。这些方案包括水力传导率随深度衰减的多种表示，土壤深度随地形的变化，以及各向异性。我们评估流动路径，流量和水位，以量化地下概念化对水文行为的影响。我们的研究结果表明，在浅层地下增加较高的传导率层，集中了表面附近的流动路径，并增加了平均饱和流动路径速度。通过增加额外的层或引入各向异性来增加非均质性，会增加饱和流径的年龄和长度之间关系的方差。放电行为是最敏感的非均匀性在浅地下层。地下水位对分层的敏感性低于对该区域整体电导率的敏感性。各向异性限制了流径深度，控制了蓄水量，但对控制径流影响不大。流量，地下水位深度和停留时间分布的地下表示的响应的差异突出需要考虑模型的应用程序时，确定所需的复杂程度。
Mountain block systems are critical to water resources and have been heavily studied and modeled in recent decades. However, due to lack of field data, there is little consistency in how models represent the mountain block subsurface. While there is a large body of research on subsurface heterogeneity, few studies have evaluated the effect that common conceptual choices modelers make in mountainous systems have on simulated hydrology. Here we simulate the hydrology of a semi‐idealized headwater catchment using six common conceptual models of the mountain block subsurface. These scenarios include multiple representations of hydraulic conductivity decaying with depth, changes in soil depth with topography, and anisotropy. We evaluate flow paths, discharge, and water tables to quantify the impact of subsurface conceptualization on hydrologic behavior in three dimensions. Our results show that adding higher conductivity layers in the shallow subsurface concentrates flow paths near the surface and increases average saturated flow path velocities. Increasing heterogeneity by adding additional layers or introducing anisotropy increases the variance in the relationship between the age and length of saturated flow paths. Discharge behavior is most sensitive to heterogeneity in the shallow subsurface layers. Water tables are less sensitive to layering than they are to the overall conductivity in the domain. Anisotropy restricts flow path depths and controls discharge from storage but has little effect on governing runoff. Differences in the response of discharge, water table depth, and residence time distribution to subsurface representation highlight the need to consider model applications when determining the level of complexity that is needed.