CAREER: A mechanistic understanding of sediment transport in mountain streams with applications in river restoration and science education

在山区流域，陡峭的河道（坡度为3-20%）占据了河道总长度的大部分，并影响了向下游输送泥沙和水到大城市地区和水电设施。 这些河流提供的沉积物的体积和粒度也影响下游河流恢复项目的成功。 流域尺度的泥沙输移预测需要在恢复设计，以考虑对水生生物栖息地，水质和通道稳定性的沉积物供应的影响。大多数泥沙输运方程是基于经验拟合的数据测量在达到规模，不包括颗粒运动的力学，并制定了低梯度的渠道。 据推测，陡峭，粗糙的河流推移质输运方程需要包括：1）的湍流和颗粒特性的范围，控制颗粒运动的启动，2）的应力和推移质输运率的空间变异补丁，和3）的时间和空间变化的影响，沉积物供应。 水槽实验将被用来测试这一假设，进一步阐明湍流和推移质输运之间的相互作用，并告知理论和经验模型，预测泥沙通量在达到规模。 这些模型将在当地和国际现场进行测试，并通过提供对陡峭溪流中沉积物通量的准确和机械估计来改变景观演变和河流恢复设计的预测。 这项研究的智力价值是一个基本的和预测性的了解过程中，控制湍流和泥沙输运陡峭的河流。沉积物运输和河流恢复的框架将用于教育研究生，本科生和K-12学生对水资源和功能流生态系统的重要性。提出了四个教育目标：1）一系列研究生课程，培养批判性思维，科学写作和跨学科团队技能，2）本科生和研究生的国际研究经验，3）教育K-12学生河流过程的计划，以及4）一个新的女性科学营，鼓励年轻女性进入数学，科学和工程职业生涯。

In mountainous drainage basins, steep channels (gradients of 3-20%) occupy the majority of the total channel length and influence the downstream delivery of sediment and water to metropolitan areas and hydropower facilities. The volume and grain sizes of sediment supplied from these streams also impact the success of downstream river restoration projects. Basin-scale sediment transport predictions are needed in restoration design to account for the effect of sediment supply on aquatic habitat, water quality, and channel stability. Most sediment transport equations are based on empirical fits to data measured at the reach-scale, do not include the mechanics of grain motion, and were developed for lower-gradient channels. It is hypothesized that bedload transport equations for steep, rough streams need to include: 1) the range of turbulence and grain properties that control the initiation of grain motion, 2) the spatial variability in stresses and bedload transport rates on patches, and 3) the effect of temporal and spatial variations in sediment supply. Flume experiments will be used to test this hypothesis, further elucidate the interaction between turbulence and bedload transport, and inform theoretical and empirical models that predict sediment flux at the reach scale. Such models will be tested in local and international field locations and will transform predictions of landscape evolution and river restoration design by providing accurate and mechanistic estimates of sediment flux in steep streams. The intellectual merit of this research is a fundamental and predictive understanding of the processes that control turbulence and sediment transport in steep streams. The framework of sediment transport and river restoration will be used to educate graduate, undergraduate, and K-12 students on the importance of water resources and functioning stream ecosystems. Four education objectives are proposed: 1) a series of graduate student classes that develop critical thinking, scientific writing, and interdisciplinary team skills, 2) international research experience for undergraduate and graduate students, 3) programs to educate K-12 students on river processes, and 4) a new Women in Science Camp that encourages young women to enter careers in math, science, and engineering.