Modeling groundwater transit time distributions and means across a Nebraska watershed: effects of heterogeneity in the aquifer, riverbed, and recharge parameters
Modeling groundwater transit time distributions and means across a Nebraska watershed: effects of heterogeneity in the aquifer, riverbed, and recharge parameters
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DOI：
10.1016/j.jhydrol.2022.128891
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发表时间：
2022-12
影响因子：
6.4
通讯作者：
Can Zeyrek;A. Mittelstet;T. Gilmore;V. Zlotnik;D. Kip Solomon;D. Genereux;Eric Humphrey;Nawaraj Shrestha
中科院分区：
文献类型：
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作者：
Can Zeyrek;A. Mittelstet;T. Gilmore;V. Zlotnik;D. Kip Solomon;D. Genereux;Eric Humphrey;Nawaraj Shrestha
地下水通过时间分布(TTDS)，即从地下水位补给到地表水体排放通过含水层的旅行时间，提供了关于地下水流系统水文响应时间尺度的关键信息。利用三维稳态MODFLOW USG-MODPATHD3DU模型，研究了补给空间格局、含水层非均质性和河床导水率的系统变化对地下水向中上游罗普河(UMLR)和水源排放的平均通过时间(MTTS)和TTDS的影响。这个5436千米的分水岭覆盖在美国内布拉斯加州沙丘的高平原含水层之上。在不同的补给、含水层和河床异质性情景下，UMLR 158公里路段的建模MTT从上游到下游的差异高达三个数量级。模拟的MTT上游站点为1~397年，下游站点为820~7968年。上游站点的TTD主要由来自浅水径流的年轻地下水组成，对河床导水率的变化很敏感。补给参数对下游站点TTD的形状和MTT的大小有更大的影响，在下游站点，较老的地下水排放到UMLR。总体而言，不同模式情景下过境时间的空间趋势为未来数字模式的精细化概念化和校准提供了重要信息。
Groundwater transit time distributions (TTDs), the travel times through the aquifer from recharge at the water table to discharge at the surface water body, provide critical information on the timescales of hydrologic response of subsurface flow systems. We investigated the effects of spatial patterns of recharge, aquifer heterogeneity, and systematic variation in riverbed hydraulic conductivity on the mean transit times (MTTs) and TTDs of groundwater discharge to the Upper Middle Loup River (UMLR) and headwaters using a 3D-steady-state MODFLOW USG-MODPATHD3DU model. This 5436 km2watershed overlies the High Plains Aquifer in the Sand Hills of Nebraska, USA. Modeled MTTs differed by up to three orders of magnitude from upstream to downstream in a 158 km section of the UMLR under varying recharge, aquifer, and riverbed heterogeneity scenarios. The simulated MTTs ranged from 1 to 397 years for upstream sites and 820 to 7968 years for the downstream sites. The TTDs at upstream sites were dominated by young groundwater from shallow flow paths and were sensitive to changes in riverbed hydraulic conductivity. Recharge parameterization had greater influence on the shape of the TTDs and magnitude of MTTs at the downstream sites, where much older groundwater discharged to the UMLR. Overall, spatial trends in transit times under varying model scenarios provided important information for refined conceptualization and calibration of future numerical models.