Abstract

While water sources that sustain many of the springs in the Mojave Desert have been poorly understood, desert wildlife and ecosystems can be highly dependent on such resources. With ever expanding use of desert groundwater, the effect of groundwater extraction on groundwater-dependent ecosystems in the Sonoran and Mojave Deserts is an ongoing concern. Springs that are more susceptible to impacts from groundwater withdrawals are typically those in hydraulic connection with surrounding basin-fill aquifer systems. Since spatial and/or temporal data gaps prevent a detailed model of the groundwater system, this evaluation of groundwater forensic approaches identifies a range of characteristics and parameters that demonstrate key indicators of spring-aquifer connectivity using data collected during a California Mojave Desert-wide spring survey conducted during 2015–2016, and subsequent monitoring and sampling events in both the California Mojave and Sonoran Deserts. In total, monitoring and sampling took place at nearly 400 springs primarily in lands managed by the U.S. Bureau of Land Management (BLM), and scattered private lands where accessible. Springs in National Park Service units such as Joshua Tree National Park, Mojave National Preserve and Death Valley National Park and in military bases were not included in the investigation scope. The multiple lines of evidence described regarding spring-aquifer connectivity include field parameters for water, such as temperature, pH, and conductivity, as well as geochemical characteristics of water, such as stable isotope and radiocarbon analyses. While other information about the setting, such as spring-site geology, are important in evaluating flow-path characteristics, simple field reconnaissance of these springs may be inconclusive as to provenance, and they are ultimately of lesser importance than the actual water characteristics in identifying spring provenance and potential hydraulic linkage to basin-fill aquifer systems that are, or may in the future, be utilized for regional groundwater development.

摘要

尽管人们对维持莫哈韦沙漠许多泉水的水源了解甚少，但沙漠野生生物和生态系统可能高度依赖此类资源。随着沙漠地下水的使用不断扩大，在索诺兰沙漠和莫哈韦沙漠中，地下水提取对依赖于地下水的生态系统的影响一直是一个令人关注的问题。较容易受到地下水抽取影响的弹簧通常是与周围的盆地填充含水层系统液压连接的弹簧。由于空间和/或时间数据的空缺阻止了地下水系统的详细模型，这项对地下水取证方法的评估确定了一系列特征和参数，这些特征和参数使用2015-2016年在加利福尼亚莫哈韦沙漠进行的全春季春季调查期间收集的数据，以及随后在加利福尼亚州和加利福尼亚州进行的监测和采样事件，证明了春季-含水层连通性的关键指标。莫哈韦沙漠和索诺兰沙漠。总体而言，监测和采样发生在将近400个泉水上，主要是在美国土地管理局（BLM）管理的土地上，以及可访问的分散私人土地上。调查范围不包括约书亚树国家公园，莫哈韦国家自然保护区和死亡谷国家公园等国家公园服务部门的温泉和军事基地的温泉。关于弹簧-含水层连通性的多种证据包括水的现场参数，例如温度，pH和电导率，以及水的地球化学特征，例如稳定的同位素和放射性碳分析。尽管有关设置的其他信息（例如泉水所在地的地质信息）对于评估流径特征很重要，但这些泉水的简单野外勘测在物源方面可能尚无定论，并且最终在确定水源方面不如实际水质重要。泉源和与盆地填充含水层系统的潜在水力联系，已经或将来可能被用于区域地下水开发。例如稳定同位素和放射性碳分析。尽管有关设置的其他信息（例如泉水所在地的地质信息）对于评估流径特征很重要，但这些泉水的简单野外勘测在物源方面可能尚无定论，并且最终在确定水源方面不如实际水质重要。泉源和与盆地填充含水层系统的潜在水力联系，已经或将来可能被用于区域地下水开发。例如稳定同位素和放射性碳分析。尽管有关设置的其他信息（例如泉水所在地的地质信息）对于评估流径特征很重要，但这些泉水的简单野外勘测在物源方面可能尚无定论，并且最终在确定水源方面不如实际水质重要。泉源和与盆地填充含水层系统的潜在水力联系，已经或将来可能被用于区域地下水开发。