Estimation of Streambed Groundwater Fluxes Associated with Coaster Brook Trout Spawning Habitat

Abstract

We hypothesized that the spatial distribution of groundwater inflows through river bottom sediments is a critical factor associated with the distribution of coaster brook trout (a life history variant of Salvelinus fontinalis) spawning redds. An 80-m reach of the Salmon Trout River, in the Huron Mountains of the upper peninsula of Michigan, was selected to test the hypothesis based on long-term documentation of coaster brook trout spawning at this site. A monitoring well system consisting of 22 wells was installed in the riverbed to measure surface and subsurface temperatures over a 13-month period. The array of monitoring wells was positioned to span areas where spawning has and has not been observed. Over 200,000 total temperature measurements were collected from five depths within each monitoring well. Temperatures in the substrate beneath the spawning area were generally less variable than river temperatures, whereas temperatures under the nonspawning area were generally more variable and closely tracked temporal variations in river temperatures. Temperature data were inverted to obtain subsurface groundwater velocities using a numerical approximation of the heat transfer equation. Approximately 45,000 estimates of groundwater velocities were obtained. Estimated groundwater velocities in the spawning area were primarily in the upward direction and were generally greater in magnitude than velocities in the nonspawning area. Both the temperature and velocity results confirm the hypothesis that spawning sites correspond to areas of significant groundwater flux into the river bed.

Spatiotemporal variability of hyporheic exchange through a pool‐riffle‐pool sequence

“…While there are some streams that may be “losing” and “gaining” throughout the year, it is probably more common for reaches to oscillate between net gain and net loss as seasons change from a wet season (or melt season) and a dry season [e.g., Whiting and Pomeranets , ]. Because many aquatic biota use hyporheic habitats for only a portion of their life cycle, these seasonal shifts in context may hold important clues about habitat preferences that would not be evident if dynamic fluxes were not considered [ Baxter et al ., ; Geist and Dauble , ; Malcolm et al ., ; Van Grinsven et al ., ]. The temporal context is also an important link between reach‐scale hyporheic fluxes and runoff generation throughout the watershed, particularly in snowmelt‐driven watersheds, where local groundwater recharge and streamflow are likely to be asynchronous.…”

Supplementary material to "Working backwards from streambed thermal anomalies: hydrogeologic controls on preferential brook trout spawning habitat in a coastal stream"

“…In contrast, the Spawn sites all show isotope signals that fall along the local meteoric waterline and therefore likely represent recharge to the hillslopes more local to the river. These localized groundwater flow systems would be expected to be less influenced by regional groundwater contamination, which is widespread in the regional Cape Cod aquifer (Walter and Masterson, 2002).…”

“…Isotope samples were analyzed by the U.S. Geological Survey Stable Isotope Laboratory using dual-inlet isotope-ratio mass spectrometry. A substantial fraction of regional Cape Cod shallow groundwater exchanges with the numerous groundwater flow-through lakes as it discharges to the coast (Walter and Masterson, 2002). It is therefore assumed that the regional Cape Cod groundwater isotopic signature is likely to indicate evaporative processes (LeBlanc et al, 2008), offering a contrasting signal from locally recharged hillslope groundwater (no substantial evaporation).…”

A Review of the Hyporheic Zone, Stream Restoration, and Means to Enhance Denitrification

“…Careful measurements of temperature changes in streams have even been used to quantify hyporheic exchange rates (Westhoff et al 2011). Consistent temperatures are advantageous for salmonid spawning, and subsurface temperatures are more constant in upwelling zones (van Grinsven et al 2012).…”