Subsurface Structure and Flow Regime for Rocky Mountain Hillslopes with Different Geologies

美国西部山区的积雪融化是干旱山间盆地农业、工业、城市和自然生态系统的重要水源。山区融雪向径流的转化受气候、植被和地质相互作用的影响。地下水在将水从入渗点输送到溪流中的作用目前还知之甚少。这项研究使用最先进的仪器对六个不同地质条件的落基山脉山坡的地下部分进行了成像。此外，还利用计算机模拟模型计算地下水流和蓄水动态，并预测径流。一个重要的目标是找到地质和流态之间的可预测的关系。由此得到的洞察力对于理解当前和未来气候和土地利用情景对径流的规模和时间的影响至关重要。这些见解将促进机构、公司和个人更好地管理土地和水资源。作为该项目的一部分，两名研究生和三名本科生将在广泛的地质和水文测量以及计算机模拟技术方面获得经验。此外，还将与怀俄明大学地质博物馆合作建造一个巡回博物馆展览，以吸引落基山脉地区的居民和游客参与地质和水文研究。这项研究结合了最先进的地球物理和水文测量和建模技术，研究了三种不同地质条件下的山坡地下水流和蓄水情况。将回答以下研究问题：Q1。在这项研究中选择的六个落基山脉山坡的风化带有多不同或相似，代表了古老的花岗岩表面，年轻的火山表面，以及前寒武纪岩石上的新冰川沉积？，Q2。落基山脉六个山坡的地下水力特性和流态可以确定到什么程度？和Q3。山坡地下模型的复杂性对流域尺度上的径流和水量平衡预测有何影响？其中三个山坡位于怀俄明州，目前正在由两名调查人员测量。爱达荷州(2个)和新墨西哥州(1个)的临界区观测站提出了另外三个山坡。这六个山坡是成对的，所以三个地质都由两个山坡代表。测量将包括确定地下孔隙度结构的浅层地震折射，确定包气带水动态的延时电阻率层析成像，以及评估水输入和山坡水文响应的水文监测。数值模型将与参数估计算法相结合来估计地下水力参数。综合流域模型将用于研究坡面模型复杂性对径流和水量平衡预报的影响。这项研究的重点是地下水文过程和径流产生，但也有助于更好地了解山坡风化过程和山坡生态功能。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Snowmelt from mountainous regions in the western US is a vital source of water for agriculture, industry, cities, and natural ecosystems in the dry inter-mountain basins. The transformation of snowmelt into streamflow in mountainous regions is influenced by the interplay between climate, vegetation, and geology. The role of the subsurface in transporting water from the point of infiltration to the stream is currently poorly understood. This study uses state-of-the-art instruments to image the subsurface of six Rocky Mountain hillslopes with different geologies. In addition, computer simulation models are used to calculate subsurface water flow and storage dynamics and to predict streamflow. An important goal is to find predictable relationships between geology and flow regime. The resulting insights are critical for understanding the impact of current and future climate and land use scenarios on the magnitude and timing of streamflow. Such insights will facilitate better land and water management by agencies, companies, and individuals. Two graduate students and three undergraduate students will gain experience with a broad range of geological and hydrological measurement and computer simulation techniques as part of the project. In addition, a traveling museum exhibit will be constructed in collaboration with the University of Wyoming Geological museum to engage residents and visitors of the Rocky Mountain region in geological and hydrological research. The study combines state-of-the-art geophysical and hydrological measurement and modeling techniques to examine subsurface water flow and storage in hillslopes with three different geologies. The following research questions will be answered: Q1. How different or similar are the weathering zones of the six Rocky Mountain hillslopes selected for this study that represent old granitic surfaces, young volcanic surfaces, and recent glacial deposits over Precambrian rock?, Q2. To what level of detail can subsurface hydraulic properties and flow regimes be determined for the six Rocky Mountain hillslopes?, and Q3. What is the impact of hillslope subsurface model complexity on streamflow and water balance predictions at the watershed scale? Three of the hillslopes are in Wyoming and are currently being measured by the two investigators. The other three hillslopes are proposed in Critical Zone Observatories in Idaho (2) and New Mexico (1). The six hillslopes are paired so that each of the three geologies are represented by two hillslopes. Measurements will consist of shallow seismic refraction to determine subsurface porosity structure, time-lapse electrical resistivity tomography to determine vadose zone water dynamics, and hydrological monitoring to assess water inputs and hillslope hydrologic response. Numerical models will be combined with parameter estimation algorithms to estimate subsurface hydraulic parameters. Integrated watershed modeling will be used to investigate the effect of hillslope model complexity on streamflow and water balance predictions. The study focusses on subsurface hydrological processes and streamflow generation but also contributes to a better understanding of hillslope weathering processes and hillslope ecological functioning.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.