Quantifying Lateral Flow of Water in Alpine Snowpacks Using High Resolution Geophysical Techniques

使用高分辨率地球物理技术量化高山积雪中水的横向流动

• 批准号: 0943710
• 负责人: Hans-Peter Marshall
• 金额: $ 22.9万
• 依托单位: Boise State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-07-01 至 2014-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0943710&HistoricalAwards=false
• 关键词: Quantifying; Lateral; Flow; Water; Alpine

Quantifying lateral flow of water in alpine snowpacksusing high resolution geophysical techniquesPROJECT ABSTRACTIn addition to inherent variability in falling snow, both wind redistribution and variations in radiation balance cause large spatial variability in the timing and location of input of snowmelt to the ground. However, even when these major drivers are accounted for, physically based hydrologic modeling is challenging, suggesting that there may be other processes controlling when and where snowmelt enters the subsurface. Most snowmelt models treat the snowpack as homogeneous, and assume that all meltwater moves vertically to the ground. Numerous experiments have shown that snowmelt follows a complicated path through the snowpack, moving both laterally along stratigraphic boundaries and vertically in concentrated cylindrical channels. While theoretical approaches have been developed to account for heterogeneities such as stratigraphy and vertical preferential flow paths, they are not applied in practice due to a lack of quantitative field-based measurements.We suggest that lateral movement of liquid water during melt and rain-on-snow events can be an important mechanism of water redistribution in steep, snow-dominated catchments. Flow of water within snowpacks is a complicated and poorly understood phenomenon. Permeability boundaries cause slope-parallel lateral flow over large distances, and coupled with cylindrical, vertical melt pathways, there is a resulting large spatial variability at the slope scale. An improved understanding of the lateral flow of water in snow will have impacts for a broad range of problems including: 1) rain-on-snow events which have the potential to cause flooding and landslides. The snowpack provides a large mass of water to melt, and may provide a faster route for the rainwater to enter streams. 2) A quantitative understanding of the timing and location of snowmelt within the seasonal snowpack is necessary in order to evaluate the importance of lateral flow on the seasonal hydrograph in snowmelt-dominated basins, and 3) quantifying lateral flow in snow is important for estimating the travel-time of meltwater traveling from polar ice caps and glaciers to the ocean which in turn is a basis for predicting time scales of sea level rise. Understanding the importance of lateral flow during rain-on-snow is important for forecasting floods, wet snow avalanches, and landslides, as mid-winter rain may become more common in a warming climate.This project will leverage state-of-the-art geophysical tools that already exist in-house at our institution to quantify lateral flow of water in alpine snowpacks. These include 1) measurements sensitive to microstructure which controls hydraulic conductivity, 2) rapid, non-destructive methods for measuring snow stratigraphy, depth, snow water equivalent, and liquid water content of both snow and the underlying soil, and 3) direct in-situ measurements of liquid water content. These measurements, combined with tracer experiments, will be used to characterize the snowpack conditions at the microscale that lead to lateral flow. The detailed snow and soil characterization will be used to estimate hydrologic properties for initial model conditions. Field data will be used to develop hydrologic models (using HYDRUS2D) of the experimental hillslopes to evaluate the relative importance of lateral flow in snow and soil in snowmelt-dominated catchments.

定量的水在alpine snowpacksusing高分辨率地球物理techniques项目摘要除了固有的变化，降雪，风的再分配和辐射平衡的变化导致大的空间变化的时间和位置的输入融雪到地面。 然而，即使考虑到这些主要驱动因素，基于物理的水文建模也是具有挑战性的，这表明可能有其他过程控制融雪何时何地进入地下。 大多数融雪模型将积雪视为均匀的，并假设所有的融水垂直移动到地面。 大量的实验表明，融雪遵循一个复杂的路径通过积雪，既横向沿着地层边界移动，并在集中的圆柱形通道垂直。 虽然理论上的方法已经发展到解释的异质性，如地层和垂直优先流路径，他们不适用于在实践中，由于缺乏定量的实地measurement.We建议，在融化和雨雪事件的液态水的横向运动可以是一个重要的水再分配机制陡峭，雪为主的集水区。水在积雪中的流动是一种复杂且知之甚少的现象。 渗透率边界引起大距离的斜坡平行的横向流动，并与圆柱形，垂直熔体路径，有一个由此产生的大的空间变异性在斜坡尺度。 更好地了解雪中水的横向流动将对广泛的问题产生影响，包括：1）有可能导致洪水和山体滑坡的雨对雪事件。 积雪提供了大量的水融化，并可能提供一个更快的路线，雨水进入溪流。 2)定量了解的时间和位置的季节性积雪内的融雪是必要的，以评估的重要性，横向流动的季节性过程线在融雪为主的流域，和3）量化横向流动雪是重要的，估计的旅行时间的融水从极地冰盖和冰川的海洋，这反过来又是一个基础，预测海平面上升的时间尺度。 了解雪上降雨过程中横向流动的重要性对于预测洪水、湿雪雪崩和山体滑坡非常重要，因为在气候变暖的情况下，仲冬降雨可能会变得更加常见。该项目将利用我们机构内部已经存在的最先进的地球物理工具来量化高山积雪中的水的横向流动。 这些包括1）对控制水力传导性的微观结构敏感的测量，2）用于测量雪层、深度、雪水当量以及雪和底层土壤的液态水含量的快速、非破坏性方法，以及3）液态水含量的直接原位测量。 这些测量结果与示踪剂实验相结合，将用于表征导致侧向流动的微观积雪条件。 详细的雪和土壤特性将用于估计初始模型条件下的水文特性。 现场数据将被用来开发水文模型（使用HYDRUS2D）的实验山坡，以评估在融雪为主的集水区的雪和土壤的侧流的相对重要性。