Collaborative Research: Incorporating hillslope transport into laboratory landscape experiments

丘陵和多山的地形有一种明显的趋势，即把自己组织成重复的山脊和山谷。这些地貌序列的间距决定了水系的密度和山脉的高度，取决于渠道中平流输沙和山坡扩散输沙之间的竞争。尽管数值模型的结果很有希望，但气候和构造如何调节山坡和水道过程在确定景观解剖方面的相对有效性尚不清楚。为了测试对这些基本景观特性的控制，这项研究将在现有的积极侵蚀景观的实验室模型中加入扩散式的山坡运输。我们的物理实验将通过在景观表面的针状冰中加入沉积物来产生可重复的山坡输送，而渠道将通过喷头的降水来演变。由于实验将能够隔离和操纵坡度和沟渠过程的速率，我们将记录在广泛的气候和构造情景下的地貌发展。此外，作为第一个明确包含坡面过程的物理实验，这项研究将在一个与地球大部分地区-S地表相关的系统中跟踪地形调整的动态，如山脊迁移和排水捕获。以前气候控制景观演变的数值和实验研究通常集中在降水如何驱动渠道径流和山谷切割。然而，气候也通过冰缘过程和植被的变化来调节山坡上的泥沙生产和运输，从而深刻地影响景观的地形组织。我们实验景观的结果将为破译地形中过去的气候信号以及预测未来气候变化对景观演变的影响提供信息。物理实验是推广和招募科学的有力工具，因为它们能够以实时和高度可访问的方式减少复杂的、百万年规模的过程。这笔资金还将用于建造专门为教学和推广而设计的实验景观仪器。除了支持博士生的教育，这笔助学金还包括为当地社区学院的学生提供研究经验，并为本科生举办景观演变研讨会。

Hilly and mountainous terrain has a remarkable tendency to organize itself into repeating ridges and valleys. The spacing of these landform sequences, which sets the density of drainage networks and the height of mountains, depends on the competition between advective sediment transport in channels and diffusive sediment transport on hillslopes. Despite promising results from numerical models, it is unclear how climate and tectonics modulates the relative effectiveness of hillslope and channel processes in determining landscape dissection. To test controls on these fundamental landscape properties, this research will incorporate diffusive hillslope transport into an existing laboratory model for actively eroding landscapes. Our physical experiments will generate reproducible hillslope transport via sediment incorporation in needle ice on the landscape surface while channels will evolve through precipitation from sprinklers. Because the experiments will be able to isolate and manipulate rates of hillslope and channel processes, we will document landform development under a wide range of climatic and tectonic scenarios. Furthermore, as the first physical experiment to explicitly incorporate hillslope processes, this research will track the dynamics of landform adjustment, such as ridge migration and drainage capture, in a system with relevance to much of the Earth?s surface.Previous numerical and experimental studies of climate controls on landscape evolution generally focus on how precipitation drives channel discharge and valley incision. However, climate also modulates sediment production and transport on hillslopes through changes in periglacial processes and vegetation, profoundly affecting the topographic organization of landscapes. Results from our experimental landscape will inform efforts to decode past climate signals in topography as well as predict the effect of future climate change on landscape evolution. Physical experiments are a powerful tool for outreach and science recruitment because of their ability to reduce complex, million-year-scale processes in a real-time and highly accessible fashion. The funds will also provide for the construction of an experimental landscape apparatus designed explicitly for teaching and outreach. In addition to supporting the education of a PhD student, this grant includes research experience for students from local community colleges and provides for the development of a landscape evolution seminar for undergraduates.