Abstract:

The emergence of multiscale, nested flow systems is intrinsic to hydrologic systems across landscapes. This seminar explores this multiscale behavior in two distinct hydrologic system scales. In mountainous terrains, the role of deep Regional Groundwater Flow (RGF) is of great importance for the lowlands’ overall water, energy, and solute budgets. To this end, we implemented flow and transport models for a series of synthetic mountain-to-valley transition systems. These models underscore the critical role of topography and geology in the RGF and the spatial patterns of solutes and energy, resulting in unique patterns of subsurface electrical resistivity and constraining our ability to image the subsurface with electromagnetic geophysical methods. Our analyses assess the potential of magnetotelluric surveys to map the nested nature of mountain groundwater flow and provide vital information to characterize unconventional groundwater resources. In the second part, we explore the role of meanders as natural biogeochemical reactors along river corridors. We used groundwater flow and transport models to assess the role of the meander’s geometry and topology and the RGF in the hydrodynamics and denitrification potential of the sinuosity-driven hyporheic zone. Our results show that a narrow meander neck shields the hyporheic zone from the modulating effects of RGF. Moreover, this model allows us to explore when a meander acts as a net nitrogen source or sink by using a handful of dimensionless physical and biogeochemical parameters. Finally, to upscale these analyses from individual reaches to watersheds or continents, we developed a novel Python package that enables the supervised and unsupervised identification of meandering features along river networks using a spectral decomposition approach. These efforts pave the way for more accurate quantification of sinuosity-driven hyporheic exchange and provide critical information for river restoration strategies.

Webinar