Collaborative Research: Bedrock and Sediment Controls on River Incision, Henry Mountains and Navajo Mountain, Utah

在过去的十年里，在了解气候、侵蚀和构造之间的相互作用方面取得了相当大的进展。这主要是通过河流切口的通用规则集来完成的，这些规则集将不同的侵蚀机制组合在一起。从这些一般性分析中我们获得了很多：我们现在清楚地知道我们需要更好地了解什么以及为什么。然而，显然有必要开发和测试河流切入基岩的特定过程模型。特别是，岩体质量、泥沙负荷和侵蚀效率之间的定量关系是重要的未知数；必须更好地了解河流形态和切割速率的岩性和沉积物控制，才能根据驱动景观演化的气候和构造因素自信地解释景观。最近的理论和实验进展表明，只有详细的基于物理的切口模型才能为进一步的重大进展提供合适的框架，前提是能够找到合适的现场地点并系统地收集全面的数据集。我们提出了一个耦合的实地，实验室和理论调查，重点是排水渠道亨利山脉和附近的纳瓦霍山，犹他州。这些野外地区为研究基岩和沉积物对河流切口和形态的控制提供了很好的自然实验。初步的DEM和遥感分析以及初步的野外观测显示，作为基岩岩性和闪长岩沉积物供应的函数，河道形态（坡度、宽度、岩石暴露百分比、侵蚀床形式、粗糙度）存在显著的系统性差异。提出的研究的两个主要目标是：(1)测试，完善和扩展跳跃-磨损河流切口模型[Sklar, 2003；Sklar and Dietrich, 1998；Sklar和Dietrich， 2001]，以及(2)开发和测试一种在地貌相关尺度上客观测量基岩可蚀性（或岩体质量）的原位方法。具体来说，我们将测试五个重点假设，利用亨利山脉和附近纳瓦霍山脉油田现场条件提供的机会。跳跃-磨损模型是迄今为止发展最完善的河流切割模型，它对河道形态、泥沙负荷、基岩可蚀性、岩石暴露率和切割速率之间的相互关系做出了具体的、可测试的定量预测。实验数据支持的模型预测[Sklar, 2003；Sklar和Dietrich， 2001]对造山带演化和构造与气候的相互作用有着深远的影响，但尚未在实地得到验证。延伸和更广泛的影响：人们越来越广泛地认识到，构造和地貌之间的动态相互作用在造山运动中起着重要作用。岩性和沉积控制在景观和造山带演化中起着关键作用，但研究很少。我们对基岩岩性、沉积物特征和河道形态之间联系的理解取得了根本性的进展，这在解决预测、减少和减轻土地利用影响以及恢复受损河流栖息地的应用问题方面也具有潜在的巨大价值。这项研究的大部分内容将定义麻省理工学院（MIT）准备从事学术生涯的博士生J. Johnson博士论文研究项目的核心。此外，我们的研究每年将邀请麻省理工学院的一名或多名本科生参与一个特殊的研究项目，并涉及以本科生为主的旧金山州立大学的本科生。此外，这个合作研究项目的好处是聘请了L. Sklar（旧金山州立大学最近聘请的助理教授）参与国家科学基金资助的研究，为他提供了参与麻省理工学院研究生监督和培训的机会。此外，除了在科学文献中传播我们的成果外，我们正在编制一个GIS格式的数字数据库，其中包括公共领域的数字高程数据、地质图、卫星图像和地貌实地数据，我们将在网上公开提供这些数据。最后，这个项目的主题和领域都非常适合教育推广。我们建议(1)在犹他州国家公园、纪念碑和休闲区的游客中心为公众制作海报和小册子；(2)设计一个网站，在大峡谷切口和科罗拉多高原景观的背景下，特别是大峡谷和峡谷地的形成，传播我们的研究结果。与峡谷地国家公园护林员的非正式讨论得到了热情的回应。

There has been considerable progress in the past decade on understanding the interactions amongclimate, erosion, and tectonics. This has been accomplished primarily with generic rule sets for river incision that lump together a diverse set of erosional mechanisms. Much has been gained from these generic analyses:we now know well what we need to know better and why. There is a clear need, however, to develop and test process-specific models of river incision into bedrock. In particular, the quantitative relationships among rock mass quality, sediment load, and erosional efficiency stand out as important unknowns; the lithologic and sediment controls on river morphology and incision rate must be better understood before landscapes can be confidently interpreted in terms of the climatic and tectonic factors that drive landscape evolution.Recent theoretical and experimental advances demonstrate that only detailed physically-based incision models provide a suitable framework for significant further progress, assuming a suitable field site can be found and a comprehensive data set systematically collected.We propose a coupled field, laboratory and theoretical investigation, focused on channels draining the Henry Mountains and nearby Navajo Mountain, Utah. These field areas present an excellent natural experiment for studing bedrock and sediment controls on river incision and morphology. Preliminary DEM and Remote sensing analyses and initial field observations reveal significant, systematic differences in channel morphology (slope, width, percent rock exposure, erosional bed forms, roughness) as a function of substrate lithology and diorite sediment supply.The two principal goals of the proposed research are (1) test, refine, and extend the saltation-abrasion river incision model [Sklar, 2003; Sklar and Dietrich, 1998; Sklar and Dietrich, 2001], and (2) to develop and test an in-situ method for objective measurerment of substrate erodibility (or rock mass quality) at geomorphically relevant scales. Specifically, we will test five focused hypotheses, exploiting the opportunity presented by fieldconditions in the Henry Mountains and nearby Navajo Mountain field sites. The saltation-abrasion model is the most fully developed river incision model to date and makes specific, testable quantitative predictions about the interrelations among channel morphology, sediment load, substrate erodibility, percent rock exposure, and incision rate. Model predictions supported by experimental data [Sklar, 2003; Sklar and Dietrich, 2001] have far-reaching implications orogen evolution and the interaction of tectonics and climate, but have not been tested in the field.Outreach and Broader Impacts: There is broad and growing recognition that dynamic interactionsbetween tectonics and geomorphology play a fundamental role in orogenesis. Lithologic and sediment controls play a critical, but little studied role in landscape and orogen evolution. Fundamental advances in our understanding of the linkages between bedrock lithology, sediment characteristics and channel morphology are also of potentially enormous value in solving applied problems of anticipating, minimizing and mitigating for landuse impacts and restoring damaged riverine habitat. Much of the proposed study will define the core of a doctoral thesis research program of J. Johnson, an MIT Ph.D. student preparing for an academic career.Moreover, our study will engage one or more undergraduates each year at MIT in a special research project, and involve undergraduates at SFSU, a primarily undergraduate institution. In addition, this collaborative research project has the benefit of engaging L. Sklar - a recently hired assistant professor at SFSU - in NSFsponsored research, providing him the opportunity to participate in the supervision and training of an MIT graduate student. Also, in addition to dissemination of our results in the scientific literature, we are compiling a digital database in GIS format with public domain digital elevation data, geologic maps, satellite images, andgeomorphic field data as layers that we will make publicly available on the Web. Finally, both the subject matter and field areas of this project are well suited to educational outreach. We propose to (1) develop poster displays and brochures for the general public at visitors centers at national parks, monuments and recreation areas in Utah, and (2) design a website to communicate our results in the context of canyon incision and the landscapes of the Colorado Plateau, especially the formation of Grand Canyon and Canyonlands. Informal discussions with park rangers at Canyonlands NP have been met with enthusiasm.