Threshold hydrologic change across the intermittent-persistent snow transition

该项目将开发一个地理合成的雪，径流和土壤水分数据在美国西部和分析将提供关键信息，可用于确定地区最容易受到大的水文变化，由于较小的积雪积累。 所产生的数据集将公开提供，这些信息可纳入土地和水资源管理，特别是在缺乏水文数据的地方。该项目将培训一名博士生和本科生研究助理，为教育推广和学生招聘开发一个交互式数字显示器，并利用土壤湿度模拟开发一个水文学课堂活动。 冬季持续积雪的减少影响着全世界山区和高纬度地区的水资源，迫切需要了解水资源对积雪损失的脆弱性。指导这项研究的中心假设是，持续积雪的损失引发了水流和土壤水分的变化，但这种变化的幅度在更干旱的气候中更大。该项目将记录美国西部持续积雪过渡的地理分布，并研究这些过渡对径流和土壤湿度的影响。将利用中分辨率成像分光仪积雪图像和SNOTEL站点的雪水当量数据绘制积雪过渡图。然后，将在年度-十年时间尺度和事件-季节时间尺度上将降雪过渡指数与径流和土壤湿度数据进行比较。HYDRUS-1D模拟土壤水分变化，以应对不同的情况下，雪的持久性将开发SNOTEL网站在两个不同的气候区域，以研究雪损失和水文响应之间的过程相互作用如何随气候变化。该研究综合了一种自上而下的方法，研究了雪持续性地理梯度上的径流和土壤水分变化，并采用了一种自下而上的过程建模方法，研究了土壤水分如何响应从持续性到间歇性雪的过渡。多尺度方法将有助于了解区域长期模式如何与个别季节的当地条件联系起来。

This project will develop a geographic synthesis of snow, streamflow, and soil moisture data across the western U.S. and the analyses will provide key information that can be used to identify areas most vulnerable to large hydrologic changes due to smaller snowpack accumulation. Datasets produced will be publicly available and this information can be incorporated into land and aquatic resource management, particularly in locations that lack hydrologic data. The project will train a PhD student and undergraduate research assistants, develop an interactive digital display for education outreach and student recruitment, and develop a hydrology class activity using soil moisture simulations. Loss of persistent winter snowpack impacts water resources in mountain and high latitude regions throughout the world, and the need to understand water resource vulnerability to snow loss is pressing. The central hypothesis guiding this research is that loss of a persistent snowpack triggers changes in both stream flow and soil moisture, but the magnitude of this change is greater in more arid climates. This project will document the geographic distribution of intermittent-persistent snow transitions in the western U.S. and examine how streamflow and soil moisture are affected by these transitions. Snow transitions will be mapped using both MODIS snow cover imagery and snow water equivalent data from SNOTEL sites. Indices of snow transitions will then be compared to streamflow and soil moisture data at both annual-decadal time scales and event-seasonal time scales. HYDRUS-1D simulations of soil moisture changes in response to varying scenarios of snow persistence will be developed for SNOTEL sites in two different climate regions to examine how process interactions between snow loss and hydrologic response vary with climate. The study synthesizes a top-down approach examining runoff and soil moisture changes across geographic gradients of snow persistence with a bottom-up process modeling approach examining how soil moisture responds to a transition from persistent to intermittent snow. The multi-scale approach will help in understanding how regional long-term patterns link with local conditions in individual seasons.