MULTISCALE GROUNDWATER DYNAMICS AND ITSINFLUENCE ON SOLUTE AND ENERGY FATE AND TRANSPORT

h2ogeo.upc.edu/es/
Groundwater Hydrogeology and geochemistry webinar.
Autor: Daniel Gonzalez-Duque (Ohio State University)
From Mountains to Bedforms: Multiscale Groundwater Dynamics and its
Influence on Solute and Energy Fate and Transport
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.