Exploration of groundwater flowpaths and effective recharge in the Amargosa Desert, Nevada, using multivariate statistical analysis and elevation-dependent chloride mass-balance method
Exploration of groundwater flowpaths and effective recharge in the Amargosa Desert, Nevada, using multivariate statistical analysis and elevation-dependent chloride mass-balance method
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使用多元统计分析和依赖海拔的氯化物质量平衡方法探索内华达州阿马戈萨沙漠的地下水流径和有效补给
DOI：
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发表时间：
2017
影响因子：
2.8
通讯作者：
J. Walton
中科院分区：
文献类型：
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作者：
O. Al;A. Woocay;J. Walton
在美国内华达州阿玛戈萨沙漠附近，使用多元统计方法(MSMS)和一种简单的依赖海拔的氯离子质量平衡法(MIRE)对地下水流动路径和有效补给进行了估计。将MSM应用于主要离子数据，以解释不同地下水化学物种之间的关系，确定确定地下水流动路径和演化所需的水化学相，并确定地表和地质特征对地下水的影响。对于每个确定的分水岭，使用平均地下水氯浓度，并通过假设降水中氯的空间和时间恒定浓度是海拔的函数，评估在所有陆地高程以上的受试者分水岭的氯离子沉降率。仅阿马戈萨沙漠的海拔就被评估为高于平均海平面1200米(m-amsl)，这是基于内华达州国家安全局遗址上海拔最低的永久泉水之一甘蔗泉(1237 m-amsl)的高度。这个最低海拔是我们计算的截止海拔，在这个高度上，降雨量被认为对补给做出了重大贡献。根据在线绘图软件ACME Labs Mapper 2.1的海拔数据和PRISM气候小组PRISM的降水数据，对与海拔有关的降水进行了评估。这些分析进一步深入了解了该区域的水文学，并表明地表和地质特征对干旱地区的地表水渗透和地下水有很大的影响。具体地说，提出了在短暂的Fortymile冲刷周围过去集中补给的证据，以及地质断层与地下水渗透和流动路径之间的相互作用。此外，基于水化学的地下水流动似乎被主要断层分割。据估计，阿马戈萨沙漠附近的地下水补给量约为15280英亩英尺/年。
Estimation of groundwater flowpaths and effective recharge was performed in the vicinity of Amargosa Desert, Nevada, USA, using multivariate statistical methods (MSMs) and a simple elevation-dependent chloride mass-balance method modified by estimating a minimum effective recharge elevation (MERE). MSMs were applied to major ion data to explain the relationships among different groundwater chemical species, define hydrochemical facies needed to determine groundwater flowpaths and evolution, and identify the influence of surface and geologic features on groundwater. For each defined watershed, an average groundwater chloride concentration is used and the chloride deposition rate is assessed in the subject watersheds over all land elevations above the estimated MERE by assuming two constant spatial and temporal concentrations of chloride in precipitation which is a function of elevation. The MERE for the Amargosa Desert was appraised as 1200 m above mean sea level (m-amsl), based upon the elevation of the orifice of Cane Spring (1237 m-amsl), one of the lowest elevation, permanent springs, on the Nevada National Security Site. This minimum elevation is the cutoff altitude for our calculations at which precipitation is considered to make a significant contribution to recharge. Elevation-dependent precipitation was evaluated relating elevation data from the online mapping software ACME Labs Mapper 2.1 and precipitation data from the PRISM Climate Group’s PRISM. These analyses provide further insight into the hydrology of the region and demonstrate the strong impact surface and geologic features can have on surface water infiltration and groundwater in arid regions. Specifically, evidence is presented of past focused recharge around the ephemeral Fortymile Wash and interaction between geologic faults and groundwater infiltration and flowpaths. In addition, groundwater flow, based upon water chemistry, appears to be segmented by major faults. Groundwater recharge in the vicinity of the Amargosa Desert has been estimated around 15,280 acre-ft/year.