Collaborative Research: From rock to regolith to rivers: weathering, grain size, and controls on soil production and fluvial incision

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Soil is a vital resource but processes controlling soil production are not well understood. Data collected in previously NSF-funded studies, along with new data, will be used to better understand how soil is produced in different environments. The depth of soil is likely closely linked to the soil production rate and how rivers erode. How rivers and soils interact has practical consequences for river infrastructure and human impacts on landscapes such as deforestation or forest fires. How sustainable is soil given a changing Earth? Undergraduate and graduate students and a post-doctoral scholar will contribute to this research project. The team will also use 3D printers to make synthetic landscapes to be used as part of outreach to K-12 students who are visually impaired or have Autism Spectrum Disorder.In the Rio Blanco watershed in the Luquillo Critical Zone Observatory, we will map patterns in surface soil thickness, grain size, and soil chemistry across the landscape and tie these to new rates of soil production and soil grain residence time. Theoretical hillslope-channel coupling will be modeled using the Landlab modeling toolkit and a recently published analytical model that predicts the grain size distribution of sediment fed to channels as a function of climate and erosion rate, which controls the residence time of soil particles. We will also build a new fluvial incision modeling component to incorporate the influence of sediment load, including grain size, on bedrock incision rates. Further, data from the Rio Blanco will be used to calibrate a Landlab model.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.