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Research Themes

Fate and transport in fluvial systems - theoretical upscaling of local processes

stream with rocks and grass
ND-LEEF stream (credit: Nicole Gorman)

Carbon, nutrients, and contaminants are transformed in highly reactive regions of the stream. The overall reactivity therefore depends both on local reactivity of these regions and on the rate that reactive materials are delivered to these regions. For example, while it is relatively simple to determine whether streams are net sources or sinks of CO2, it remains extremely difficult to predict how carbon fluxes will change with changing physical (e.g,. flow, temperature) or chemical (oxygen levels) conditions.

Under this theme, we combine field-scale tracer experiments, numerical experiments and analytical modeling in an effort to better predict how societally-relevant materials are transported and transformed in streams.

Basin-Scale Hydrologic Variability

dry dirt

There is growing evidence that changing precipitation patterns are impacting not only freshwater ecosystems, but also human decisions. We are investigating the mechanistic links between changing hydrology and myriad processes at the scale of river basins. This work is primarily focused on developing analytical models based on theory of stochastic processes.

Turbulent interactions between surface and ground waters

purple circles with pink purple background

We investigate how materials are transported across and within the hyporheic zone, a region where stream water and groundwater mixes. In energetic streams with coarse-grained beds (e.g., gravels), turbulent eddies rapidly pulse materials into the streambed, but this process is not well characterized in transport models. We conduct physical and numerical experiments to develop improved models of mass transport in streams and rivers.

Biological drivers of solute and particle transport

black and red swirls

Water’s movement controls the habitability of any freshwater environment by delivering  nutrients, redistributing contaminants, and imparting shear stresses on organisms. In turn, organisms can both directly and indirectly control the movement of mass in freshwater systems.

We investigate feedbacks between hydrology and biological activity, in an effort to understand how they evolve in time and how they are sensitive to external environmental perturbations.