Comparison of Heat and Bromide as Ground Water Tracers Near Streams

Abstract

Heat and bromide were compared as tracers for examining stream/ground water exchanges along the middle reaches of the Santa Clara River, California, during a 10-hour surface water sodium bromide injection test. Three cross sections that comprise six shallow (<1 m) piezometers were installed at the upper, middle, and lower sections of a 17 km long study reach, to monitor temperatures and bromide concentrations in the shallow ground water beneath the stream. A heat and ground water transport simulation model and a closely related solute and ground water transport simulation model were matched up for comparison of simulated and observed temperatures and bromide concentrations in the streambed. Vertical, one-dimensional simulations of sediment temperature were fitted to observed temperature results, to yield apparent streambed hydraulic conductivities in each cross section. The temperature-based hydraulic conductivities were assigned to a solute and ground water transport model to predict sediment bromide concentrations, during the sodium bromide injection test. Vertical, one-dimensional simulations of bromide concentrations in the sediments yielded a good match to the observed bromide concentrations, without adjustment of any model parameters except solute dispersivities. This indicates that, for the spatial and temporal scales examined on the Santa Clara River, the use of heat and bromide as tracers provide comparable information with respect to apparent hydraulic conductivities and fluxes for sediments near streams. In other settings, caution should be used due to differences in the nature of conservative (bromide) versus nonconservative (heat) tracers, particularly when preferential flowpaths are present.

Conservative Solute Versus Heat Transport in Porous Media During Push-pull Tests

“…Other authors reported values for longitudinal and transverse thermal dispersivity equal to 100 and 10 m, respectively, (Smith and Chapman 1983) or longitudinal thermal dispersivity values in the order of magnitude of 0.01 m to 1 m in case of water exchange between streams and groundwater reservoirs (Niswonger and Prudic 2003). Constantz et al (2003) derived that thermal dispersivity is significantly smaller than solute dispersivity. Bear (1972), Ingebritsen andSanford (1998), andHopmans et al (2002), among others, concluded that effects of thermal dispersion are negligible compared to diffusion and considered α * to be zero.…”

“…For instance, Bravo et al (2002) involved measurements of surficial temperature in the parameter estimation process of a coupled groundwater and heat flow model of a wetland system in Wisconsin. Constantz et al (2003) made a comparison between heat and bromide as groundwater tracer in the vicinity of streams. Other examples are cited in the paper of Anderson (2006).…”

Heat, B10-Enriched Boric Acid, and Bromide as Recycled Groundwater Tracers for Managed Aquifer Recharge: Case Study

“…Therefore heat as a tracer at MAR sites has a great potential because it has been used near streams (Lapham 1989;Stonestrom and Constantz 2003;Constantz et al 2003;Anderson 2005). A few recent studies have employed heat as a tracer at spreading basins to determine spatial and temporal variations of infiltration rates (Racz et al 2012;.…”

Studying groundwater and surface water interactions using airborne remote sensing in Heihe River basin, northwest China

“…For semi-arid and arid regions, the water exchange between surface water and groundwater is the critical process of the entire water cycle (Constantz et al, 2003a). Tracers are widely used by hydrologists to indicate the interaction pattern between surface water and groundwater (Banks et al, 1996;Torgersen et al, 2001;Constantz et al, 2003b;Huang et al, 2012). Utilizing geochemical tracers in surface water and groundwater interaction studies bears the disadvantages of uncertainties from the spatial heterogeneity and measurement equipment errors.…”