Collaborative Research: From Roots to Rock - Linking Evapotranspiration and Groundwater Fluxes in the Critical Zone

合作研究：从根部到岩石 - 将关键区域的蒸散量和地下水通量联系起来

• 批准号: 1446231
• 负责人: Kamini Singha
• 金额: $ 24.48万
• 依托单位: Colorado School of Mines
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-03-01 至 2018-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1446231&HistoricalAwards=false
• 关键词: Collaborative; Research; Roots; Rock; Linking; Collaborative; Research; Roots; Rock; Linking

The water cycle describes the movement of water on, above, and below Earth's surface and establishes where water exists. Fluxes quantify the rate of water movement among reservoirs such as groundwater, surface water, and atmospheric water vapor. Evapotranspiration is the primary mechanism supporting the surface-to-atmosphere water flux; it is the combined effect of evaporation from surface-water bodies and transpiration by plants drawing water from the soil and evaporating it from leaf surfaces. The National Research Council has identified understanding the interconnections between evapotranspiration and groundwater fluxes to be one of the most important challenges facing hydrologists today. This project addresses a critical knowledge gap in how subsurface water storage mediates the connection between evapotranspiration and groundwater dynamics such as water-table elevation and flow rates. Elucidating the connections between evapotranspiration and groundwater recharge that may limit irrigation agriculture and aquifer pumping is directly relevant to societal needs for food and water. The study focuses on a long-term research site in Oregon. Based on global climate models of the Pacific Northwest, stresses placed on groundwater by prolonged evapotranspiration are likely to become increasingly important to water availability for downstream communities. Results from this work will be incorporated into undergraduate curriculums. Underrepresented undergraduates will be engaged and mentored throughout the project.Two conceptual models have been developed to explain evapotranspiration-baseflow interactions - riparian interception and hydraulic pumping - but their implications for critical zone models have yet to be explored. This project will test these conceptual models through isotopic measurements and subsurface imaging. The project will (1) use the temporal and spatial change in soil and tree xylem water isotopes to examine subsurface connections between transpiration, groundwater and streamflow; (2) image changes in moisture content in the subsurface through the weathered saprolite and into the unweathered critical zone; and (3) assess the importance of subsurface properties and antecedent moisture on the transfer of the evapotranspiration signal to the stream. The research will provide novel contributions by (1) identifying the mechanisms by which subsurface hydrological responses are coupled to tree physiological processes at the hillslope scale and (2) integrating real-time observations, isotopic analysis, and geophysical approaches to identify how evapotranspiration-groundwater interactions vary with space, time, and antecedent moisture. These results can transform the understanding of the interactions among surface water, groundwater, and soil moisture and the role of vegetation dynamics controlling the multi-scale hydrological functioning of terrestrial ecosystems.

水周期描述了水在地球表面上，上方和下方的流动，并确定存在水的地方。 通量量化了地下水，地表水和大气水蒸气等水库之间的水流动速率。蒸散是支持地表到偏流水通量的主要机制。这是从地表水体中蒸发的综合作用以及植物从土壤中抽水并从叶子表面蒸发的植物的蒸腾作用。 国家研究委员会已经确定理解蒸散量和地下水助理之间的互连是当今水文学家面临的最重要挑战之一。 该项目解决了地下水存储如何介导蒸散量与地下水动力学（例如水表升高和流速）之间的联系的关键知识差距。 阐明可能限制灌溉农业和含水层泵送的蒸散剂与地下水补给之间的联系与食品和水的社会需求直接相关。 该研究重点是俄勒冈州的长期研究地点。 基于太平洋西北地区的全球气候模型，长时间蒸散量在地下水上的压力可能对下游社区的水的供应越来越重要。 这项工作的结果将纳入本科课程中。在整个项目中将参与和指导代表性不足的本科生。已经开发了两个概念模型来解释蒸发式 - 疏松式 - 贝斯流相互作用 - 河岸拦截和液压抽水 - 但它们对关键区域模型的影响尚未探索。该项目将通过同位素测量和地下成像测试这些概念模型。 该项目将（1）使用土壤和木质部水同位素的时间和空间变化检查蒸腾，地下水和水流之间的地下连接； （2）图像通过风化的腐生岩和不受限制的关键区域的地下中水分​​含量变化； （3）评估地下特性和先行水分对蒸散信号转移到流的重要性。 这项研究将通过（1）确定地下水文反应与山坡级别的树生理过程的机制提供新的贡献，以及（2）整合实时观测，同位素分析和地球物理方法，以识别蒸发 - 疏水 - 地球培训 - 蒸发 - 地球接地之间的相互作用如何与空间，时间，时间，隔离剂和远处的水分变化。这些结果可以改变对地表水，地下水和土壤水分之间相互作用的理解，以及控制陆地生态系统多规模水文功能的植被动力学的作用。