NSF/EAR-BSF: Assessing controls on hydrologic connectivity, plant water availability and degradation risk in drylands with isotope tracers and Lagrangian modeling

NSF/EAR-BSF：利用同位素示踪剂和拉格朗日模型评估旱地水文连通性、植物水可用性和退化风险的控制

• 批准号: 1632494
• 负责人: Sally Thompson
• 金额: $ 28.25万
• 依托单位: University of California-Berkeley
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-08-01 至 2020-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1632494&HistoricalAwards=false
• 关键词: NSF; EAR; BSF; Assessing; controls

Due to the lack of vegetation associated with many dryland ecosystems, rainfall generates significant overland flow so that runoff/runon processes become important for providing flows to vegetated sites where water can infiltrate, leading to complex patterns of water resources available to plants. Predicting these flow patterns from easily observable features such as vegetation and topographic patterns, would be instrumental in evaluating landscape vulnerability to desertification. In addition, it would provide design strategies for restoration activities by optimizing vegetation selection, hillslope contouring and planting design. This research aims to develop improved techniques to enable such predictions through models that test runon-runoff process against the experimental behavior of isotopic tracers and through the development of new techniques that improve the realism of modeled vegetation and topographic surfaces. The research will support two doctoral research students (one in Israel and one in the US), and research exchange between research sites at UC Berkeley and Ben Gurion University of the Negev. It will enable outreach activities that use the research findings to inform land restoration planning and guidelines, in conjunction with partners at the UC Berkeley College of Environmental Design and the Keren Kayemeth LeIsrael-Jewish National Fund in Israel.The project will advance predictions of dryland vulnerability to disruption of runon-runoff processes based on the spatial organization of vegetation, hillslope topography and storm characteristics. The aim of such predictions is to identify high priorities for intervention to prevent degradation, and to inform restoration designs, focusing on modification of the vegetation distribution and hillslope form. Previous modeling attempts to generalize the predictions of plant water availability based on spatial pattern were constrained in two ways: (i) The models used to make predictions are generally tested against indirect metrics of the runon-runoff process, such as net discharge from a runoff plot, rather than against observations of site-to-site source-sink transport of water during storm events; thus their ability to constrain the source-sink behavior within a runoff site is questionable. (ii) The model experiments used to connect dryland surface features to water redistribution rely on individual realizations of idealized land surfaces. Consequently, uncertainty is poorly characterized, and the meaning of the resulting metrics for real landscapes is unclear. This proposal exploits isotopic tracer experiments to reveal patterns of connectivity and water availability to vegetation on a well-characterized dryland hillslope at the Lehavim Long Term Ecological Research site in Israel. The patterns will be used to test the predictions of runoff-runon models by adapting these models to predict Lagrangian transport of water using Coupled Eulerian-Lagrangian Modeling techniques. Model experiments with the tested model will then draw on the emerging field of multi-point statistics to enable realistic realizations of landscape surface features, allowing uncertainty in predicted water availability, degradation risk or restoration quality to be characterized. The research will provide insights into landscape-scale controls on desertification vulnerability based on the likelihood that runoff is captured on a hillslope, or is lost via export from vegetated slopes.

由于许多旱地生态系统缺乏植被，降雨产生大量的地表径流，因此径流/径流过程对于向水可以渗透的植被地区提供水流变得很重要，导致植物可用的水资源模式复杂。从植被和地形模式等易于观察的特征预测这些流动模式将有助于评估景观对荒漠化的脆弱性。此外，研究亦会为修复工程提供设计策略，包括优化植物选择、山坡轮廓和种植设计。这项研究的目的是开发改进的技术，使这样的预测通过模型，测试径流径流过程对同位素示踪剂的实验行为，并通过开发新的技术，提高模拟植被和地形表面的真实性。该研究将支持两名博士研究生（一名在以色列，一名在美国），以及加州大学伯克利分校和内盖夫本古里安大学研究中心之间的研究交流。 该项目将与加州大学伯克利分校环境设计学院和以色列Keren Kayemeth LeIsrael-Jewish National Fund的合作伙伴一道，开展外联活动，利用研究成果为土地恢复规划和准则提供信息，并将根据植被的空间组织、山坡地形和风暴特征，推进旱地易受径流-径流过程中断影响的预测。这种预测的目的是确定预防退化干预的高度优先事项，并为恢复设计提供信息，重点是改变植被分布和山坡形态。以前的模拟尝试，以概括的预测植物水分的可用性的基础上的空间格局的限制在两个方面：（i）用于进行预测的模型通常是测试对径流径流过程的间接指标，如从径流小区的净排放，而不是对观测站点到站点的源汇输送的水在暴雨事件;因此，它们在径流地点内约束源-汇行为的能力是值得怀疑的。(ii)用于将旱地地表特征与水分再分布联系起来的模型实验依赖于对理想化地表的个别实现。因此，不确定性的特点很差，并由此产生的真实的景观指标的意义是不清楚的。该提案利用同位素示踪实验，揭示了以色列Leibrim长期生态研究站点一个特征鲜明的旱地山坡上植被的连通性和水供应模式。 该模式将被用来测试径流径流模型的预测，通过调整这些模型来预测拉格朗日运输的水耦合欧拉-拉格朗日建模技术。 然后，将利用多点统计这一新兴领域，对经过测试的模型进行模型实验，以使景观表面特征能够得到现实的实现，从而能够对预测的水供应、退化风险或恢复质量的不确定性进行表征。 这项研究将根据径流在山坡上被捕获的可能性，或通过从植被覆盖的山坡上输出而流失的可能性，深入了解对荒漠化脆弱性的小规模控制。

项目成果

Emulation of the Saint Venant Equations Enables Rapid and Accurate Predictions of Infiltration and Overland Flow Velocity on Spatially Heterogeneous Surfaces

圣维南方程的仿真能够快速准确地预测空间异质表面上的渗透和地表流速

• DOI: 10.1029/2019wr025146
• 发表时间: 2019
• 期刊: Water Resources Research
• 影响因子: 5.4
• 作者: Crompton, Octavia;Sytsma, Anneliese;Thompson, Sally
• 通讯作者: Thompson, Sally

Resistance Formulations in Shallow Overland Flow Along a Hillslope Covered With Patchy Vegetation

• DOI: 10.1029/2020wr027194
• 发表时间: 2020-05
• 期刊: Water Resources Research
• 影响因子: 5.4
• 作者: O. Crompton;G. Katul;S. Thompson

Sensitivity of dryland vegetation patterns to storm characteristics

旱地植被格局对风暴特征的敏感性

• DOI: 10.1002/eco.2269
• 发表时间: 2021
• 期刊: Ecohydrology
• 影响因子: 2.6
• 作者: Crompton, Octavia Thompson