Zhi Li

Zhi Li

Postdoc at PNNL. Interested in numerical modeling of geophysical flow & solute/reactive/sediment transport, and river dynamics. Views and posts here are my own.

A hydrogeophysical framework to assess infiltration during a simulated ecosystem-scale flooding experiment

Published in Journal of Hydrology, 2023

Recommended citation: Adebayo, M. B., Bailey, V. L., Chen, X., Hopple, A. M., Jiang, P., Li, B., Li, Z., Martin-Hayden, J. M., Megonigal, P. J., Regier, P. J., Rich, R., Stegen, J. C., Smith, R. W., Ward, N. D., Woodard, S. C., & Doro, K. O. (2023). A hydrogeophysical framework to assess infiltration during a simulated ecosystem-scale flooding experiment. Journal of Hydrology, 130243. doi: https://doi.org/10.1016/j.jhydrol.2023.130243

See paper on the publisher’s site: https://doi.org/10.1016/j.jhydrol.2023.130243

Highlights

  • Combined information from geophysics and soil cores delineated soil stratigraphic heterogeneity.

  • Time-lapse electrical resistivity monitoring revealed preferential infiltration paths.

  • Hydrological states derived from resistivity monitoring improved a surface-subsurface flow model.

  • The hydrogeophysical framework captured subsurface flow in response to flooding.

Abstract

This study presents a framework to quantify changes in soil saturation in response to flooding caused by extreme hydrologic perturbation on coastal ecosystems at the interfaces and transition between terrestrial and aquatic systems. Subsurface heterogeneity limits the use of in situ measurements to quantify subsurface flow during flooding due to the spatial discontinuity in the measured data. While geophysical methods, including time-lapse electrical resistivity imaging (ERI), are increasingly used to monitor soil hydrological processes, their abilities to parameterize flow models have been underutilized. This study combines background ERI, ground penetrating radar (GPR), time-lapse ERI, soil characterization, and a numerical flow model developed using an Advanced Terrestrial Simulator (ATS) code to quantify the infiltration pathway and describe the hydrological dynamics during a simulated flooding experiment. We assessed the use of two conceptual models developed using [1] ERI and GPR data that described the stratigraphic distribution, and time-lapse ERI that mapped permeability contrast, and [2] information from a national soil database for capturing changes in saturation. Combining the ERI and GPR results with soil core data revealed the stratigraphic heterogeneity at the site with a silty clay layer from 1 – 2 m between an overlying loamy topsoil and an underlying saturated silty sand. This silty clay layer could restrict deep infiltration. The time-lapse ERI showed up to a 35% decrease in resistivity, which correlated with soil moisture data (R2 value > 0.53) and revealed preferential infiltration zones used to inform the flow model. Numerical simulation results from both the geophysics- and soil database-informed models quantified changes in soil saturation with calculated soil moistures that agreed with field data. The geophysics-informed model captured more of the system’s variability, reflective of shallow subsurface heterogeneities. The framework presented will serve as a precursor for a robust ecohydrological model that can describe the impacts of extreme events induced by climate change on coastal ecosystems.