NSF Award
2413944
Accurate modeling of sediment mechanical behavior is crucial for building and preserving our roads, bridges, and housing; notably to resist floods and landslides following heavy rains. The failure of dams and landslides present some of the highest hazards. The latest ASCE report on the state of infrastructure in the United States gave a D grade to the US dams. In 2017, 15,498 dams in the US (17 %) were classified as high-hazards. Extra water-flow through earthen dams and soils is known as a risk factor for landsliding or breaching. To better tackle these high-stakes problems the investigators will develop and test a new model that considers how such groundwater flow impacts sediment creep. These project outputs will then help with the most fundamental part of risk prevention or mitigation. The principal investigator based at Clark University, in Worcester, MA, will conduct an activity for the students of the Columbus Park School in Worcester, for them to develop physical intuition of how dams (such as the Patch Pond Dam) can hold or sometimes break. The co-principal investigator based at the Naval Postgraduate School (NPS) in Monterey, CA, will bring STEM challenges to the local middle and high schools as part of the NPS annual Design Challenge.<br/><br/>Sediment creep is ubiquitous, and it precedes failure in most landscapes. Quantifying the sediment creep flux over hill slopes is crucial for predicting the long-term evolution of landscapes. Current models are determined empirically over geological time scales and are diffusion-like, although the mechanics of sediment creep on all time scales remain poorly understood. The risk of hillslope destabilization has been observed as increasing with excess groundwater, yet, there is no model linking groundwater flow and sediment creep. The investigators propose to develop a new model of sediment creep and test it against new and complementary data sets from laboratory experiments and field surveys. The proposed new model for sediment creep builds on results recently obtained by the principal investigator to explicitly include the mechanical effects of groundwater flow, friction, and gravity on local sediment creep deformation. Laboratory and field data will be acquired before the breaching of sandy dams allowing the investigators to test their new landscape evolution model, over time scales of minutes to weeks and from far to near-failure. Fieldwork will be conducted at the Carmel River, CA, prior to seasonal breaching at the river mouth. The new sediment creep function will be implemented as part of an open-source modeling Toolkit.<br/><br/>This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
