TY - JOUR
T1 - Spatially telescoping measurements for improved characterization of ground water-surface water interactions
AU - Kikuchi, C. P.
AU - Ferré, T. P.A.
AU - Welker, J. M.
N1 - Funding Information: We gratefully acknowledge the invaluable guidance and support from Steve Frenzel and Dan Long of the USGS Alaska Science Center. Colleague reviews by Edward Moran and Donald Rosenberry greatly improved the quality of this manuscript. Excellent field assistance was provided by Ann Marie Larquier, Charles Grammer, and Shamariah Hale. Grey Nearing provided valuable technical support in filtering temperature time series records. Data collection and analysis for this project were generously supported by funding from the Alaska Department of Natural Resources and the US Fish and Wildlife Service.
PY - 2012/6/26
Y1 - 2012/6/26
N2 - The suite of measurement methods available to characterize fluxes between groundwater and surface water is rapidly growing. However, there are few studies that examine approaches to design of field investigations that include multiple methods. We propose that performing field measurements in a spatially telescoping sequence improves measurement flexibility and accounts for nested heterogeneities while still allowing for parsimonious experimental design. We applied this spatially telescoping approach in a study of ground water-surface water (GW-SW) interaction during baseflow conditions along Lucile Creek, located near Wasilla, Alaska. Catchment-scale data, including channel geomorphic indices and hydrogeologic transects, were used to screen areas of potentially significant GW-SW exchange. Specifically, these data indicated increasing groundwater contribution from a deeper regional aquifer along the middle to lower reaches of the stream. This initial assessment was tested using reach-scale estimates of groundwater contribution during baseflow conditions, including differential discharge measurements and the use of chemical tracers analyzed in a three-component mixing model. The reach-scale measurements indicated a large increase in discharge along the middle reaches of the stream accompanied by a shift in chemical composition towards a regional groundwater end member. Finally, point measurements of vertical water fluxes - obtained using seepage meters as well as temperature-based methods - were used to evaluate spatial and temporal variability of GW-SW exchange within representative reaches. The spatial variability of upward fluxes, estimated using streambed temperature mapping at the sub-reach scale, was observed to vary in relation to both streambed composition and the magnitude of groundwater contribution from differential discharge measurements. The spatially telescoping approach improved the efficiency of this field investigation. Beginning our assessment with catchment-scale data allowed us to identify locations of GW-SW exchange, plan measurements at representative field sites and improve our interpretation of reach-scale and point-scale measurements.
AB - The suite of measurement methods available to characterize fluxes between groundwater and surface water is rapidly growing. However, there are few studies that examine approaches to design of field investigations that include multiple methods. We propose that performing field measurements in a spatially telescoping sequence improves measurement flexibility and accounts for nested heterogeneities while still allowing for parsimonious experimental design. We applied this spatially telescoping approach in a study of ground water-surface water (GW-SW) interaction during baseflow conditions along Lucile Creek, located near Wasilla, Alaska. Catchment-scale data, including channel geomorphic indices and hydrogeologic transects, were used to screen areas of potentially significant GW-SW exchange. Specifically, these data indicated increasing groundwater contribution from a deeper regional aquifer along the middle to lower reaches of the stream. This initial assessment was tested using reach-scale estimates of groundwater contribution during baseflow conditions, including differential discharge measurements and the use of chemical tracers analyzed in a three-component mixing model. The reach-scale measurements indicated a large increase in discharge along the middle reaches of the stream accompanied by a shift in chemical composition towards a regional groundwater end member. Finally, point measurements of vertical water fluxes - obtained using seepage meters as well as temperature-based methods - were used to evaluate spatial and temporal variability of GW-SW exchange within representative reaches. The spatial variability of upward fluxes, estimated using streambed temperature mapping at the sub-reach scale, was observed to vary in relation to both streambed composition and the magnitude of groundwater contribution from differential discharge measurements. The spatially telescoping approach improved the efficiency of this field investigation. Beginning our assessment with catchment-scale data allowed us to identify locations of GW-SW exchange, plan measurements at representative field sites and improve our interpretation of reach-scale and point-scale measurements.
KW - Environmental tracers
KW - Glacial aquifer
KW - Groundwater
KW - Spatial variability
KW - Stream
KW - Stream-aquifer interaction
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U2 - 10.1016/j.jhydrol.2012.04.002
DO - 10.1016/j.jhydrol.2012.04.002
M3 - Article
SN - 0022-1694
VL - 446-447
SP - 1
EP - 12
JO - Journal of Hydrology
JF - Journal of Hydrology
ER -