Experimental tests aimed at understanding debris flow initiation from runoff

Dr. Marisa C. Palucis已获得NSF地球科学博士后奖学金，在加州理工学院开展研究和教育计划。人们对径流产生的泥石流的引发机制和危害知之甚少，但在最近被大火烧毁的地区以及植被稀疏、基岩大量裸露的半干旱至干旱地区很常见。Palucis博士的调查将集中在研究两种可能的机制，可能引发泥石流产生的径流，逐步运输的沉积物和孔隙压力升高。结果将用于告知导致泥石流发生的位置（即斜坡）和环境条件（即粒度和流量），这是危险绘图和评估所需的，特别是在世界上易发生火灾的地区。教育计划将包括开发和实施互动桌面实验室，每月向帕萨迪纳联合学区（PUSD）内的K-8学生展示。此外，两名本科生将通过加州理工学院的夏季本科生研究员（SURF）计划进行指导，学生将在10周的课程中设计和执行水槽实验。PI将进行多个水槽实验来研究这两种机制，其中流量排放（因此，在床上的剪切应力），粒度分布（这可能会控制孔隙压力产生的颗粒流），和斜率进行了独立的测试。这些实验将提供一个有价值的和强大的数据集连接沉积物供应特性和水流水力学在陡坡。这里收集的实验数据将提供迄今为止关于沉积物输运模式的最详细的数据集之一，并将弥合实地收集的数据与实验数据之间的差距。泥石流是山地地貌的一个主要地貌过程，尽管目前大多数模型都没有将泥石流作为沉积物输运媒介。因此，更好地定义描述泥石流发生的参数空间是预测较长时间尺度景观演变的关键因素。

Dr. Marisa C. Palucis has been granted an NSF Earth Sciences Postdoctoral Fellowship to carry out a research and education plan at the California Institute of Technology. The initiation mechanisms and hazards associated with debris flows generated through runoff are poorly understood, but are common in areas recently burned by fire, and in semi-arid to arid regions with sparse vegetation and an abundance of exposed bedrock. Dr. Palucis' investigation will focus on examining two possible mechanisms that may initiate debris flows generated by runoff, progressive transport of the sediment and elevated pore pressures. The results will be used to inform about location (i.e. slopes) and environmental conditions (i.e. grain size and discharge) leading to debris flow initiation, which is needed for hazard mapping and assessment, especially in fire prone regions of the world. The education plan will consist of developing and implementing interactive desktop laboratories will be presented on a monthly basis to K-8 students within the Pasadena Unified School District (PUSD). Also, two undergraduate students will be mentored through Caltech's Summer Undergraduate Research Fellows (SURF) program, where the students will design and perform flume experiments over the course of 10-weeks.The PI will conduct multiple flume experiments to investigate these two mechanisms, where the flow discharge (and hence shear stresses on the bed), grain size distribution (which may control pore pressure generation in granular flows), and slope are tested independently. These experiments will provide a valuable and robust dataset linking sediment supply characteristics and flow hydraulics on steep slopes. The experimental data collected here will provide one of the most detailed datasets to date on sediment transport modes and will bridge the gap between data being collected in the field and experimental data. Debris flows are a major geomorphic process in mountainous landscapes, though most models currently do not account for debris flows as sediment transport agents. Therefore, better definition of the parameter space describing debris flow occurrence is a key ingredient for predicting landscape evolution over longer timescales.