Fluvial Systems and Climate in the Southwestern U.S.

美国西南部的河流系统和气候

• 批准号: 0309518
• 负责人: Jon Pelletier
• 金额: $ 17万
• 依托单位: University of Arizona
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-06-01 至 2006-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0309518&HistoricalAwards=false
• 关键词: Fluvial; Systems; Climate; Southwestern; U.S.

Fluvial Systems and Climate in the Southwestern U.S.(EAR-0309518Jon D. PelletierUniversity of ArizonaABSTRACTFluvial systems respond to changes in climate through erosion and deposition, creating a geomorphic and stratigraphic record of those changes. Alluvial fans of the southwestern U.S. preserve an excellent record of these changes from time scales of hundreds to millions of years. A large database of river and fan terraces has been developed from decades of field and laboratory work. These terraces are a major component of the Southwestern landscape, controlling flood hazards, soil development, ecosystems, and even human history. Our ability to read this record is limited, however, by a poor understanding of fluvial-system response. For example, is climate change or tectonics the major trigger of episodes of alluvial-fan deposition in the Southwest? Can the internal dynamics of the fluvial system be responsible for many of the terraces we observe? Does deposition occur during humid periods, arid periods, or the transitions between them? What are the time lags between environmental changes and fluvial-system response? To answer these questions, the project will focus on two distinct times scales. PI will reconstruct Quaternary cycles of erosion and deposition from time scales of 10 kyr to 1 Myr. This long-term focus will enable him to determine the effects of the magnitude and timing of different triggering events for the same basin. In addition, PI will reconstruct the spatial and temporal variability of latest Pleistocene and Holocene erosion and deposition from time scales of 100 yr to 10 kyr in our study area in Cuyama Valley, CA. This work will enable specific fluvial-system dynamics and hillslope-response mechanisms to be evaluated.PI has developed a process-based numerical model of channel flow and sediment transport in complex topography to enable him to better understand how fluvial systems respond to climatic changes. This model uses existing digital data sets together with scenarios of climatic and tectonic changes to model the fluvial-system evolution for specific study areas. The proposed research will determine the signatures of terrace age and morphology for each entrenchment mechanism so that the dominant processes that shape alluvial fans of the Southwest can be determined. To do this, forward modeling of fluvial-system response to different climatic and tectonic histories will be performed and their results compared against the ages and geometries of alluvial-fan terraces in our study areas.A strong background in quantitative methods is critical to providing geoscience students with the skills they need to take part in cutting-edge science. As a second phase of this project we will develop and integrate an interactive version of the numerical model into our classroom laboratory in collaboration with geoscience-education experts.

美国西南部的河流系统和气候。（0309518乔恩D. Pelletier亚利桑那大学摘要河流系统通过侵蚀和沉积对气候变化做出反应，创造了这些变化的地貌和地层记录。美国西南部的冲积扇保存了这些变化的良好记录，从数百年到数百万年的时间尺度。经过几十年的野外和实验室工作，已经建立了一个关于河流和扇体阶地的大型数据库。这些梯田是西南部景观的主要组成部分，控制着洪水灾害，土壤发育，生态系统，甚至人类历史。然而，由于我们对河流系统的反应缺乏了解，我们阅读这些记录的能力受到了限制。例如，气候变化或构造是西南部冲积扇沉积事件的主要触发因素吗？我们观察到的许多阶地是河流系统的内部动力造成的吗？沉积是发生在湿润期、干旱期还是它们之间的过渡期？环境变化与河流系统响应之间的时间差是多少？为了回答这些问题，该项目将侧重于两个不同的时间尺度。PI将重建第四纪的侵蚀和沉积循环，从10 kyr到1 Myr的时间尺度。这种长期的关注将使他能够确定同一流域不同触发事件的规模和时间的影响。此外，PI将重建的空间和时间变化的最新更新世和全新世侵蚀和沉积的时间尺度为100年至10 kyr在我们的研究领域在Cuyama谷，CA。这项工作将使特定的河流系统动力学和山坡响应机制进行评估。PI开发了一个基于过程的数值模型，在复杂地形的通道流量和泥沙输运，使他能够更好地了解河流系统如何应对气候变化。该模型使用现有的数字数据集，结合气候和构造变化情景，模拟特定研究区域的河流系统演变。拟议的研究将确定每个战壕机制的阶地年龄和形态的签名，以便确定形成西南冲积扇的主导过程。要做到这一点，河流系统对不同的气候和构造历史的响应的正演模拟将被执行，并将其结果与我们研究区域的冲积扇阶地的年龄和几何形状进行比较。作为该项目的第二阶段，我们将与地球科学教育专家合作，开发并将数字模型的交互式版本整合到我们的课堂实验室中。