Shallow bedrock limits groundwater seepage-based headwater climate refugia
Links
- More information: Publisher Index Page (via DOI)
- Data Releases:
- USGS data release - Passive seismic data collected along headwater stream corridors in Shenandoah National Park in 2016 - 2020
- USGS data release - Seismic data for study of shallow mountain bedrock limits seepage-based headwater climate refugia, Shenandoah National Park, Virginia
- USGS data release - Temperature data for study of shallow mountain bedrock limits seepage-based headwater climate refugia, Shenandoah National Park, Virginia
- Download citation as: RIS | Dublin Core
Abstract
Groundwater/surface-water exchanges in streams are inexorably linked to adjacent aquifer dynamics. As surface-water temperatures continue to increase with climate warming, refugia created by groundwater connectivity is expected to enable cold water fish species to survive. The shallow alluvial aquifers that source groundwater seepage to headwater streams, however, may also be sensitive to seasonal and long-term air temperature dynamics. Depth to bedrock can directly influence shallow aquifer flow and thermal sensitivity, but is typically ill-defined along the stream corridor in steep mountain catchments. We employ rapid, cost-effective passive seismic measurements to evaluate the variable thickness of the shallow colluvial and alluvial aquifer sediments along a headwater stream supporting cold water-dependent brook trout (Salvelinus fontinalis) in Shenandoah National Park, VA, USA. Using a mean depth to bedrock of 2.6 m, numerical models predicted strong sensitivity of shallow aquifer temperature to the downward propagation of surface heat. The annual temperature dynamics (annual signal amplitude attenuation and phase shift) of potential seepage sourced from the shallow modeled aquifer were compared to several years of paired observed stream and air temperature records. Annual stream water temperature patterns were found to lag local air temperature by ∼8–19 d along the stream corridor, indicating that thermal exchange between the stream and shallow groundwater is spatially variable. Locations with greater annual signal phase lag were also associated with locally increased amplitude attenuation, further suggestion of year-round buffering of channel water temperature by groundwater seepage. Numerical models of shallow groundwater temperature that incorporate regional expected climate warming trends indicate that the summer cooling capacity of this groundwater seepage will be reduced over time, and lower-elevation stream sections may no longer serve as larger-scale climate refugia for cold water fish species, even with strong groundwater discharge.
Publication type | Article |
---|---|
Publication Subtype | Journal Article |
Title | Shallow bedrock limits groundwater seepage-based headwater climate refugia |
Series title | Limnologica - Ecology and Management of Inland Waters |
DOI | 10.1016/j.limno.2017.02.005 |
Volume | 68 |
Year Published | 2018 |
Language | English |
Publisher | Elsevier |
Contributing office(s) | OGW Branch of Geophysics |
Description | 15 p. |
First page | 142 |
Last page | 156 |
Google Analytic Metrics | Metrics page |