Critical evaluation of stable isotope mixing end-members for estimating groundwater recharge sources: case study from the South Rim of the Grand Canyon, Arizona, USA
Critical evaluation of stable isotope mixing end-members for estimating groundwater recharge sources: case study from the South Rim of the Grand Canyon, Arizona, USA
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用于估计地下水补给源的稳定同位素混合端元的批判性评估：美国亚利桑那州大峡谷南缘的案例研究
DOI：
10.1007/s10040-020-02194-y
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发表时间：
2020
影响因子：
2.8
通讯作者：
Kimberly R. Beisner
中科院分区：
文献类型：
--
作者：
John E. Solder;Kimberly R. Beisner
美国亚利桑那州大峡谷南缘的泉水和地下水对该地区的生态系统、居民（人和动物）和经济都很重要。然而，这些泉水和渗漏可能容易受到污染、地下水开采增加或因气候变化而减少补给的影响。本研究采用统计方法对降水、地表水和地下水中的δ2H和δ18O进行了研究，以确定地下水的来源。以冬季（11 - 4月）降水和夏季（5 - 10月）地表水径流为模型端元，建立了δ18O混合模型。冬季补给分数（Fwin）表明南缘地下水主要来源于融雪和冬雨，平均Fwin为0.97±0.09。研究区最高海拔地区的地下水比冬季末端的地下水更枯竭，这表明地下水的价值被高估了，或者冬季补给的很大一部分发生在低海拔地区。50个样品中有9个样品的δ2H和δ18O随经度的空间变化趋势一致，fwin值<0.9，年龄示踪数据表明泉水排出的年轻地下水不同于区域流动系统中观测到的老地下水，这支持了来自科科尼诺高原的低海拔补给。这些结果表明，需要一个新的概念模型来解释来自低海拔和夏季降水的补给来源。研究结果表明，资源管理者可能需要重新考虑南缘目前的土地利用和水资源管理做法，以保护未来的水量和水质。
Springs and groundwater seeps along the South Rim of the Grand Canyon (Arizona, USA) are important for the region’s ecosystems, residents (human and animal), and economy. However, these springs and seeps are potentially vulnerable to contamination, increased groundwater extraction, or reduced recharge due to climate change. In this study, statistical methods are used to investigate δ2H and δ18O in precipitation, surface water, and groundwater to determine groundwater source. A mixing model for δ18O is developed using statistically distinct seasonal end-members represented by modeled winter (Nov–Apr) precipitation and summer (May–Oct) surface-water run-off. The calculated fraction of winter recharge (Fwin) indicates that South Rim groundwater is primarily sourced from snow-melt and winter rains with an averageFwinof 0.97 ± 0.09. Groundwater sourced from the highest elevations of the study area are more depleted than the winter end-member, suggesting values ofFwinare overestimated or a meaningful portion of winter recharge occurs at lower elevations. Lower-elevation recharge from the Coconino Plateau is supported by consistent spatial trends in δ2H and δ18O with respect to longitude,Fwinvalues <0.9 for 9 of the 50 samples, and age tracer data indicating young groundwater discharging from springs which is distinct from old groundwater observed in the regional flow system. These results suggest a new conceptual model is needed to account for recharge sources from low elevation and summer precipitation. Results imply resource managers may need to reconsider current land-use and water management practices on the South Rim to protect future water quantity and quality.
影响因子：
3.8
作者：
Long Yang;J. Smith;M. Baeck;E. Morin;D. Goodrich
通讯作者：
Long Yang;J. Smith;M. Baeck;E. Morin;D. Goodrich