Experimental tests aimed at understanding debris flow initiation from runoff

玛丽莎·C·帕鲁西斯博士获得了美国国家科学基金会地球科学博士后奖学金，将在加州理工学院开展一项研究和教育计划。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少、基岩裸露的半干旱至干旱地区很常见。帕鲁西斯博士的研究将侧重于研究两种可能引发泥石流的机制，即径流、沉积物的逐渐输送和孔隙压力的升高。结果将被用来告知导致泥石流爆发的地点(即斜坡)和环境条件(即颗粒大小和流量)，这是进行危险测绘和评估所必需的，特别是在世界上容易发生火灾的地区。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的K-8学生介绍。此外，两名本科生将通过加州理工学院的暑期本科生研究人员计划(SURF)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个机制，其中流量(以及河床上的剪应力)、颗粒尺寸分布(可能控制颗粒流中孔隙压力的产生)和坡度都是独立测试的。这些实验将提供一个有价值和稳健的数据集，将陡坡上的泥沙供应特征和水流水力学联系起来。这里收集的实验数据将提供迄今为止关于泥沙输送方式的最详细的数据集之一，并将弥合实地收集的数据和实验数据之间的差距。泥石流是山地景观中的一个主要地貌过程，尽管目前大多数模型都没有考虑泥石流作为泥沙输送剂。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上的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.