Collaborative Research: Climatic Control of Erosion Rates and Landscape Morphology - Quantifying the Influence of Fluvial Thresholds

该项目旨在通过研究夏威夷岛屿上不断演变的地貌，促进对陆地表面对气候变化的响应的理解。这项研究将提高科学家从地形中破译过去气候记录的能力，并预测陆地表面对未来气候变化的反应。计划中的研究活动侧重于极端事件在峡谷切割中的作用——这是景观对气候变化响应的核心主题，但受到的关注不够。该团队将从夏威夷代表性不足的社区招募两名本科生参与研究工作，并参加国际专业会议，以了解机会并建立网络联系。亚利桑那州立大学和印第安纳大学将开展外展和实践公共教育活动，包括通过本科生参与研究工作。所有结果的研究数据都将公开。这项研究将扩展先前对夏威夷岛屿的研究，通过检查横跨岛屿的景观，因此景观年龄，以及在迎风坡和背风坡之间的降雨量的巨大差异，强调地貌阈值的作用和可能超过它们的极端事件。初步调查表明，所有岛屿共有的千米深峡谷被迅速切割到与今天相似的深度，之后切割停滞不前，因为河道坡度下降到与气候有关的阈值以下，无法在河道中移动大块巨石。这项研究将系统地测试夏威夷群岛峡谷切割受到巨石运输阈值限制的假设。将部署多种方法的组合，包括详细的现场测量、数字高程模型分析、嵌入熔岩流的40Ar/39Ar年代测定，以及河流沉积物中磁铁矿中宇宙成因36Cl的流域平均侵蚀率估计——这是一种最近才开发出来的新方法。这项研究为进一步了解气候对景观演变的控制提供了一个机会，并量化了河流切口阈值如何严格调节气候、地形和侵蚀速率之间的联系。夏威夷群岛为直接测量河流阈值和定量评估其调节气候控制景观演变的作用提供了独特的条件。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。

This project seeks to advance understanding of land surface response to climate change through study of evolving landforms on the Hawaiian islands. This research will improve scientists’ ability to decipher the record of past climates from landforms and to anticipate land surface response to future climate change. Planned research activities focus on the role of extreme events in canyon cutting – a topic that is central to landscape response to climate change but has received insufficient attention. The team will recruit two undergraduates from underrepresented communities in Hawaii to participate in the research effort and to attend an international professional conference to learn about opportunities and establish network connections. Outreach and hands-on public educational activities will be developed at both Arizona State University and the University of Indiana, including through participation of undergraduates in research efforts. All resulting research data will be made publicly available.This research will extend prior studies of the Hawaiian islands by examining landscapes across a span of islands, and thus landscape ages, and across the dramatic differences in rainfall between windward and leeward slopes, emphasizing the role of geomorphic thresholds and the extreme events that can exceed them. Preliminary investigation indicates that the kilometer-deep canyons common to all of the islands were cut rapidly to depths similar to the present day, after which incision stagnated because channel gradient decreased below a climate-dependent threshold for moving large boulders in channels. This study will systematically test the hypothesis that canyon cutting on the Hawaiian islands has been limited by boulder transport thresholds. A combination of methods will be deployed, including detailed field measurements, digital elevation model analyses, 40Ar/39Ar dating of inset lava flows, and estimates of catchment-mean erosion rates from cosmogenic 36Cl in magnetite in river sediment – a novel method only recently developed. This research represents an opportunity to advance understanding of climatic control on landscape evolution in general, and to quantify how fluvial incision thresholds critically modulate connections among climate, topography, and erosion rate. The Hawaiian islands provide unique conditions to directly measure fluvial thresholds and to quantitatively assess their role modulating climatic control of landscape evolution.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.