Title: Turbulence-driven hyporheic flow: connecting fine particle deposition, clogging and nutrient cycles.

Abstract: Fine natural sediments like clay particles are transported in rivers and deposited in riverbeds. Historically, these particles are considered wash-load, i.e., passive material that travels in suspension, having little to no interaction with other river processes. However, river water enters the porous beds, bringing with it those fine particles that are filtrated and immobilized in the riverbed. Over time, they accumulate and clog the riverbed voids, dramatically attenuating hyporheic exchange and diminishing the connection between surface and groundwater. Hyporheic exchange is crucial for microbially mediated transformations, such as carbon and nitrogen cycling. Despite the long stretches of land that rivers span, these biogeochemical transformations occur at limited hot spots in hyporheic zones, right on the areas that are prone to clogging. During this seminar, I will present how coupling surface water flow, hyporheic exchange and clogging led us to determine that surface water turbulence plays a key role in the deposition of fine particles in riverbeds, and in the attenuation of hyporheic exchange. These new insights will be essential to better quantify the role of rivers in carbon and nitrogen cycling estimations, and future work will be directed on upscaling these soil-grain scale processes into basic-scale models.

Bio: I am a Ph.D. candidate at Northwestern University, in Prof. Aaron Packman's laboratory. My research involves the numerical modeling of the intersections between environmental fluid dynamics and reactive transport phenomena, namely hyporheic exchange and, most recently, the bioclogging of soil-aquifer systems. I have taught the Hydraulics and Hydrology course here at Northwestern and at Universidad Nacional de Colombia, where I received my master's degree in Water Resources. Outside research, I am a contributor to the USGS's dataretrieval python package for fetching streamflow gage and water quality data, and the maintainer of stpyvista, a python package to embed 3D visualizations in web applications.