NSF-BSF: Collaborative research: The Processes and feedbacks that induce multi-scale interactions between local divide migration, drainage reversal and escarpment evolution

河网的结构影响着地球表面海拔、水和生命的空间分布。有趣的是，这种结构随着时间的推移而变化，因为水的运动将河流流域分开了。分区迁移过程发生在局部山坡尺度上，但其驱动力植根于大尺度的构造和气候变化。此外，分区迁移的局部过程影响着地球表面更广泛的地貌、水文和生态功能。本研究旨在探讨这些多尺度过程发生的机制。更具体地说，当地的地形、水文和岩性条件如何导致一连串的反馈，最终对地球系统产生大规模的影响。这个两国项目分别对以色列和美国的干旱和潮湿研究地点进行比较和对比，从而加强两国之间的研究合作。该研究小组还将为宾夕法尼亚州和科罗拉多州的小学6-8年级学生制定并领导一项强化的科学教育计划，其中包括那些入学率较高的未被充分代表的学校。水分水岭在控制景观形态和塑造水文地貌功能方面起着关键作用。分水岭的流动性与控制邻近地形的当地山坡和河流作用有着内在的联系。同时，分水岭的移动导致水系网络的重组，对大尺度的地形、均衡和地层格局产生重大影响。目前，当地的山坡和河流与流域尺度的排水重组以及与大尺度的地形和均衡变化的相互作用过程和反馈仍未被广泛探索。为了解决这些知识差距，本研究将重点放在地形陡壁和反向通道（重组的末端成员）的并置上，其中分隔迁移的初始条件相对受限。在此背景下，逆河道的拓扑结构和沉积物记录了分区迁移的历史。这些通道保存了当地岩性和水文条件如何作为引爆点的证据，这些引爆点驱动系统进入级联反应，导致排水重组、地形变化和潜在的均衡调整。为了探索这些过程的普遍性，研究人员将比较和对比以色列和美国干旱和潮湿地区的新兴景观动态，分别跨越不同的岩性和构造环境。他们将利用野外测绘和地形分析，结合景观演化模型和地质年代学分析，来约束与分水岭迁移、水流逆转和悬崖演化等不同过程相关的控制参数和速率。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。

The structure of river networks impacts the spatial distribution of elevation, water, and life across Earth’s surface. Interestingly, this structure changes through time by movement of the water divides that separate river basins. The divide migration process occurs at the local hillslope scale but the driving forces for it are rooted in large scale tectonic and climatic changes. Furthermore, local processes of divide migration influence the broader geomorphic, hydrologic, and ecologic functionality of the Earth’s surface. The proposed research explores the mechanisms through which these multi-scale processes occur. More specifically, how local topographic, hydrologic, and lithologic conditions lead to a cascade of feedbacks that can ultimately have a large scale impact on the Earth system. This binational project compares and contrasts arid and humid research sites in Israel and the USA, respectively, and will thus strengthen research collaboration between the two countries. The research team will also develop and lead an enhanced science education program for K6-8 students in schools in Pennsylvania and Colorado, including schools with high attendance of underrepresented populations.Water divides play a critical role in controlling the form of landscapes and shaping hydrologic and geomorphic functionality. The mobility of water divides is inherently related to the local hillslope and fluvial processes that control the adjacent relief. At the same time, divide mobility leads to reorganization of the drainage network, which significantly influence large-scale topographic, isostatic, and stratigraphic patterns. At present, the processes and feedbacks by which local hillslope and fluvial regimes interact with basin-scale drainage reorganization and with large scale topographic and isostatic changes remain generally unexplored. To address these knowledge gaps, this research focuses on the juxtaposition of topographic escarpments and reversed channels (an end-member of reorganization), where the initial conditions for divide migration are relatively well constrained. In this setting, the topology and sediments of the reversed channels record the history of divide migration. These channels preserve evidence for how local lithologic and hydrologic conditions act as a tipping point that drives the system into a cascading response that results in drainage reorganization, topographic changes and potentially isostatic adjustments. To explore the generality of these processes, the investigators will compare and contrast the emerging landscape dynamics in both arid and humid field sites in Israel and the USA, respectively, across different lithologic and tectonic settings. They will use field mapping and topographic analyses, in conjunction with landscape evolution models and geochronological analyses to constrain the controlling parameters and the rates associated with different processes of divide migration, flow reversals, and the evolution of escarpments.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.