Postdoctoral Fellowship: EAR-PF: Feedbacks Between Controls of Stream Dry-Down Responses at the Rain-Snow Transition

Maggi Kraft博士被授予美国国家科学基金会地球科学博士后奖学金，在爱达荷州立大学Sarah Godsey博士的指导下开展研究和专业发展活动。美国西部依靠雪作为水资源。在同一地区，大部分由融雪和雨水滋养的河流都是非多年生的，至少在一年的一部分时间里，河流会消失。全球变暖使降水阶段由雪向雨转变，但对非多年生河流降雪量变化的影响尚不清楚。本研究将融合融雪过程、植被动态和跨越雨雪过渡的三个流域的土壤特性的概念，以了解降水阶段如何影响河流的湿润和干燥。这些相互作用在控制雨雪过渡期间的水流响应方面尤为重要，因为植被、雪和土壤是相互关联的，对温度变化很敏感。虽然这些概念已经以一种分段的方式进行了评估，但它们还没有被整合起来，使我们能够准确地预测变化雪输入的非多年生流量响应。该研究将促进非多年生河流生态系统科学的发展，并为自然资源管理提供相关信息。此外，该项目将通过发展和领导一个专注于分析水流存在-缺失数据的研讨会，以及指导一名本科生开发、实施和展示一项跨学科研究项目，提供两个教育和推广机会。对积雪变化的非多年生流响应代表了我们对水文行为的理解中的一个根本差距。在雨雪过渡的流域，降水在雪和雨之间转换，为研究降水相变对径流的响应提供了理想的位置。在雨雪转换过程中，植被、雪和土壤之间的反馈是相互关联的，因此需要对耦合观测进行评价，以准确预测径流对雪水有效性变化的响应。然而，缺乏将非多年生流域的融雪、蒸腾和土壤水分的日常信号联系起来的综合研究。本研究的重点是研究非多年生河流干湿对雪、雨、植被和土壤相互作用的响应。这项研究将在美国西部半干旱地区的三个跨越雨雪过渡的流域进行，使用雪深、树液通量、水流存在-缺失、土壤湿度和高分辨率卫星图像进行测量。卫星和地面的融雪、蒸腾和土壤湿度观测将与年度和日流干湿循环响应进行比较。将创建高分辨率土壤深度图，以评估土壤水分容量、雪储存量和植被如何调节雨水或雪水输入和非多年生溪流。该研究将促进非多年生河流生态系统科学的发展，并为自然资源管理提供相关信息。本项目由地球科学部博士后奖学金计划和促进竞争性研究的既定计划（EPSCoR）共同资助。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Dr. Maggi Kraft has been awarded an NSF Earth Sciences Postdoctoral Fellowship to carry out research and professional development activities under the mentorship of Dr. Sarah Godsey at Idaho State University. The western United States relies on snow for water resources. In the same region, the majority of streams fed by snowmelt and rain are non-perennial with streamflow disappearing for at least a portion of the year. Warming global temperatures are shifting the precipitation phase from snow to rain, but the impacts of shifting snowfall fraction in non-perennial streams are not clear. This research will merge concepts of snowmelt processes, vegetation dynamics, and soil properties across three watersheds spanning the rain-snow transition to understand how precipitation phase affects stream wetting and drying. These interactions are particularly important in controlling streamflow responses across the rain-snow transition where vegetation, snow, and soils are interrelated and sensitive to changing temperatures. While these concepts have been evaluated in a piecewise manner, they have not yet been integrated to allow us to accurately predict non-perennial streamflow response to changing snow inputs. This research will advance the science of non-perennial stream ecosystems and provide relevant information for managing natural resources. Additionally, this project will develop two education and outreach opportunities via developing and leading a workshop focused on the analysis of streamflow presence-absence data and mentoring an undergraduate student to develop, implement and present an interdisciplinary research project. Non-perennial streamflow response to shifts in snow represents a fundamental gap in our understanding of hydrologic behavior. Watersheds spanning the rain-snow transition, where precipitation shifts phase between snow and rain, provide an ideal location to study streamflow response to the shifting precipitation phase. Across the rain-snow transition feedbacks between vegetation, snow, and soil are interrelated thus, evaluation of coupled observations is needed to accurately predict streamflow response to changing snow water availability. However, there is a lack of integrated studies linking daily signals of snowmelt, transpiration, and soil moisture in non-perennial watersheds. The focus of this research is to study the response of non-perennial stream dry-down and wet-up to interactions between snow, rain, vegetation, and soils. This research will be carried out in three watersheds spanning the rain-snow transition in the semi-arid western U.S. using measurements of snow depth, sap flux, stream water presence-absence, soil moisture, and high-resolution satellite imagery. The satellite-derived and ground-based snowmelt, transpiration, and soil moisture observations will be compared to the annual and diel stream wet-dry cycle response. High-resolution soil depth maps will be created to evaluate how soil water capacity, snow storage, and vegetation modulate rain or snow water inputs and non-perennial streamflow. This research will advance the science of non-perennial stream ecosystems and provide relevant information for managing natural resources.This project is jointly funded by the Division of Earth Science Postdoctoral Fellowship Program and the Established Program to Stimulate Competitive Research (EPSCoR).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.