Document Type

Article

Publication Date

2021

DOI

10.1029/2020wr027904

Publication Title

Water Resources Research

Volume

57

Issue

2

Pages

1-13

Abstract

Heat has been widely applied to trace groundwater-surface water exchanges in inland environments, but it is infrequently applied in coastal sediment where head oscillations induce periodicity in water flux magnitude/direction and heat advection. This complicates interpretation of temperatures to estimate water fluxes. We investigate the convolution of thermal and hydraulic signals to assess the viability of using heat as a tracer in environments with tidal head oscillations superimposed on submarine groundwater discharge. We first generate sediment temperature and head time series for conditions ranging from no tide to mega-tidal using a numerical model (SUTRA) forced with periodic temperature and tidal head signals. We then analyze these synthetic temperature time series using heat tracing software (VFLUX2 and 1DTempPro) to evaluate if conventional terrestrial approaches to infer fluxes from temperatures are applicable for coastal settings. We consider high-frequency water flux variability within a tidal signal and averaged over tidal signals. Results show that VFLUX2 analytical methods reasonably estimated the mean discharge fluxes in most cases but could not reproduce the flux variability within tidal cycles. The model results further reveal that high-frequency time series of water fluxes varying in magnitude and direction can be accurately estimated if paired temperatures and hydraulic heads are analyzed using numerical models (e.g., 1DTempPro) that consider both dynamic hydraulic gradients and thermal signals. These results point to the opportunity to incorporate pressure sensors within heat tracing instrumentation to better assess sub-daily flux oscillations and associated reactive processes.

Rights

© 2021. American Geophysical Union. All Rights Reserved. This article has been contributed to by US Government employees and their work is in the public domain in the USA.

Data Availability

Article states: "All models are publicly available online as detailed in their respective references. We provide model results as electronic supplementary files described in the supplementary read-me file."

The online version of the article contains supplementary material, which is available at https://doi.org/10.1029/2020WR027904

Original Publication Citation

LeRoux, N. K., Kurylyk, B. L., Briggs, M. A., Irvine, D. J., Tamborski, J. J., & Bense, V. F. (2021). Using heat to trace vertical water fluxes in sediment experiencing concurrent tidal pumping and groundwater discharge. Water Resources Research, 57(2), 1-13, Article e2020WR027904. https://doi.org/10.1029/2020wr027904

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