Using Diurnal Temperature Signals to Infer Vertical Groundwater‐Surface Water Exchange

Abstract

Heat is a powerful tracer to quantify fluid exchange between surface water and groundwater. Temperature time series can be used to estimate pore water fluid flux, and techniques can be employed to extend these estimates to produce detailed plan-view flux maps. Key advantages of heat tracing include cost-effective sensors and ease of data collection and interpretation, without the need for expensive and time-consuming laboratory analyses or induced tracers. While the collection of temperature data in saturated sediments is relatively straightforward, several factors influence the reliability of flux estimates that are based on time series analysis (diurnal signals) of recorded temperatures. Sensor resolution and deployment are particularly important in obtaining robust flux estimates in upwelling conditions. Also, processing temperature time series data involves a sequence of complex steps, including filtering temperature signals, selection of appropriate thermal parameters, and selection of the optimal analytical solution for modeling. This review provides a synthesis of heat tracing using diurnal temperature oscillations, including details on optimal sensor selection and deployment, data processing, model parameterization, and an overview of computing tools available. Recent advances in diurnal temperature methods also provide the opportunity to determine local saturated thermal diffusivity, which can improve the accuracy of fluid flux modeling and sensor spacing, which is related to streambed scour and deposition. These parameters can also be used to determine the reliability of flux estimates from the use of heat as a tracer.

Hydrogeological controls on spatial patterns of groundwater discharge in peatlands

“…The depth to which the surface diurnal temperature signal penetrates saturated near-surface sediments depends on the period of the signal, the fluid flow velocity and direction, and the physical properties of the fluid-saturated sediment (Goto et al, 2005;Hatch et al, 2006;Irvine et al, 2017;Stallman, 1965). With depth, the diurnal heat signal variation decreases in amplitude and its shifts forward in time.…”

Quantitative guidance for efficient vertical flow measurements at the sediment–water interface using temperature–depth profiles

“…However, the benefits of this approach are reduced as the discharge rate increases because the zone of useful temperature information for flux estimation collapses upward towards the water-bed interface. This approach is used to identify the maximum sediment depth for sinusoidal (i.e., diurnal) temperature signalbased analyses under varied flux conditions (e.g., Irvine, Briggs, et al, 2017) but could also be applied to estimate the shallow portion of a T-z profile with greatest curvature for steady-state analyses. This approach is used to identify the maximum sediment depth for sinusoidal (i.e., diurnal) temperature signalbased analyses under varied flux conditions (e.g., Irvine, Briggs, et al, 2017) but could also be applied to estimate the shallow portion of a T-z profile with greatest curvature for steady-state analyses.…”

Heat: An Overlooked Tool in the Practicing Hydrogeologist's Toolbox

“…This academic interest has not been reflected in the practising hydrogeological community. Thorough reviews of these periodic signal techniques are available elsewhere (Constantz 2008;Rau et al 2014;Irvine et al 2017). Many analytical techniques have been proposed to advance the seminal work of Stallman (1965) and infer vertical groundwater fluxes from multi-depth diel temperature signals recorded in shallow streambeds (Hatch et al 2006;Keery et al 2007;McCallum et al 2012;Luce et al 2013).…”