Are the Dry Valleys Getting Wetter? A Preliminary Assessment of Wetness Across the McMurdo Dry Valleys Landscape

Abstract: Intellectual Merit: Until recently, wetted soils in the Dry Valleys were generally only found adjacent to streams and lakes. Since the warm austral summer of 2002, numerous "wet spots" have been observed far from shorelines on relatively flat valley floor locations and as downslope fingers of flow on valley walls. The source of the water to wet these soils is unclear, as is the spatial and temporal pattern of occurrence from year to year. Their significance is potentially great as enhanced soil moisture may change the thermodynamics, hydrology, and erosion rate of surface soils, and facilitate transport of materials that had previously been stable. These changes to the soil active layer could significantly modify permafrost and ground ice stability within the Dry Valleys. The PIs seek to investigate these changes to address two competing hypotheses: that the source of water to these ?wet spots? is ground ice melt and that the source of this water is snowmelt. The PIs will document the spatiotemporal dynamics of these wet areas using high frequency remote sensing data from QuickBird and WorldView satellites to document the occurrence, dimensions, and growth of wet spots during the 2010-­11 and 2011-­12 austral summers. They will test their hypotheses by determining whether wet spots recur in the same locations in each season, and they will compare present to past distribution using archived imagery. They will also determine whether spatial snow accumulation patterns and temporal ablation patterns are coincident with wet spot formation. Broader impacts: One graduate student will be trained on this project. Findings will be reported at scientific meetings and published in peer reviewed journals. They will also develop a teaching module on remote sensing applications to hydrology for the Modular Curriculum for Hydrologic Advancement and an innovative prototype project designed to leverage public participation in mapping wet spots and snow patches across the Dry Valleys through the use of social media and mobile computing applications.摘要： 科学价值：长期以来，南极干谷（Dry Valleys）的湿润土壤通常仅分布在溪流与湖泊周边。自2002年南半球夏季以来，科研人员在远离岸线的相对平坦谷地区域，以及谷壁上呈顺坡延伸的流状区域，观测到大量“湿斑”。目前这类湿斑的水源尚不明确，其年际发生的时空分布模式同样有待厘清。湿斑的潜在影响不容忽视：土壤含水率提升可能改变表层土壤的热力学特性、水文过程与侵蚀速率，并促进原本稳定的物质发生迁移。这些针对土壤活动层的变化，可能显著改变南极干谷内的多年冻土与地下冰稳定性。项目首席研究员团队（Principal Investigators, PIs）旨在针对这些变化展开研究，以验证两种相互对立的假说：其一，湿斑的水源为地下冰融水；其二，水源为积雪融水。研究团队将借助QuickBird与WorldView卫星的高频遥感数据，记录2010-2011与2011-2012年南半球夏季期间湿斑的出现情况、分布范围与扩张过程，以解析这类湿润区域的时空动态。团队将通过验证湿斑是否在每个季候的相同位置重现，来检验上述假说；同时将利用存档影像对比当前与历史上的湿斑分布情况。此外，研究团队还将探明积雪的空间积累模式与时间消融模式是否与湿斑的形成存在重合。 社会效益与推广价值：本项目将培养1名研究生。研究成果将在学术会议上汇报，并发表于同行评议期刊。团队还将为《水文进展模块化课程（Modular Curriculum for Hydrologic Advancement）》开发一套遥感应用于水文学的教学模块，并打造一款创新原型项目，旨在通过社交媒体与移动计算应用，吸引公众参与南极干谷区域湿斑与积雪斑块的测绘工作。