The bulk electrical conductivity of the subsurface was indirectly measured with electromagnetic imaging (EMI) by using induced secondary electromagnetic signals generated by subsurface electrical conductors in response to transmitted electromagnetic energy (Zohdy and others, 1974). Electromagnetic induction data were collected using a DUALEM-421 (DualEM, Inc.) mounted on an inflatable stand-up paddle board about 15 centimeters above the water surface. The DUALEM-421 uses 3 transmitter-receiver coil spacings (4-, 2-, and 1-meters) and 2 orientations (vertical dipole, and horizontal dipole). Larger coil spacings interrogate a larger/deeper sampling volume than smaller coil separations. REFERENCE: U.S. Geological Survey, Techniques of Water-Resources Investigations, Book 2, Chapter D1, Zhody, A. A. R., Eaton , G. P., and Mabey, D. R. https://doi.org/10.3133/twri02D1

The bulk electrical conductivity of the subsurface was indirectly measured with electromagnetic imaging (EMI) by using induced secondary electromagnetic signals generated by subsurface electrical conductors in response to transmitted electromagnetic energy (Zohdy and others, 1974). Electromagnetic induction data were collected using a DUALEM-421 (DualEM, Inc.) mounted on an inflatable stand-up paddle board about 15 centimeters above the water surface. The DUALEM-421 uses 3 transmitter-receiver coil spacings (4-, 2-, and 1-meters) and 2 orientations (vertical dipole, and horizontal dipole). Larger coil spacings interrogate a larger/deeper sampling volume than smaller coil separations. REFERENCE: U.S. Geological Survey, Techniques of Water-Resources Investigations, Book 2, Chapter D1, Zhody, A. A. R., Eaton , G. P., and Mabey, D. R. https://doi.org/10.3133/twri02D1

This data release provides saturated sediment temperatures from vertical temperature profilers, pressure head data from co-located pizometers, and estimates of 1D groundwater flux using a recursive-estimation framework to infer groundwater/surface-water exchange based on the collected temperature time-series (approximate 1,6,16,26cm depths, AlphaMachX vertical temperature profilers) from below the sediment/water interface. A heat-transport problem was formulated as a state-space model (SSM), in which the spatial derivatives in the convection/conduction equation are approximated using finite differences. The SSM is calibrated to estimate time-varying specific discharge using the Extended Kalman Filter (EKF) and Extended Rauch-Tung-Striebel Smoother (ERTSS) algorithms. These algorithms are described in McAliley et al., 2024 (https://doi.org/10.1029/2021WR030443) and relevant algorithm has been publicly released previously on ScienceBase (https://doi.org/10.5066/P99DBTKT). This data release contains 3 zipped folders, EKF_ERTSS_results.zip that contains EKF and ERTSS groundwater flux estimates, Temperature_observations.zip that contains raw observed temperature time series, and Pressure_data.zip that contains raw observations of pressure from piezometers adjacent to vertical temperature profilers. Additionally, water pressure transducers (Onset HOBO model U20L) were suspended at two depths within 2" steel pipes with 20cm screen drivepoints that were driven vertically into bed sediments adjacent to locations TX129 and TX132.

This data release provides saturated sediment temperatures from vertical temperature profilers, pressure head data from co-located pizometers, and estimates of 1D groundwater flux using a recursive-estimation framework to infer groundwater/surface-water exchange based on the collected temperature time-series (approximate 1,6,16,26cm depths, AlphaMachX vertical temperature profilers) from below the sediment/water interface. A heat-transport problem was formulated as a state-space model (SSM), in which the spatial derivatives in the convection/conduction equation are approximated using finite differences. The SSM is calibrated to estimate time-varying specific discharge using the Extended Kalman Filter (EKF) and Extended Rauch-Tung-Striebel Smoother (ERTSS) algorithms. These algorithms are described in McAliley et al., 2024 (https://doi.org/10.1029/2021WR030443) and relevant algorithm has been publicly released previously on ScienceBase (https://doi.org/10.5066/P99DBTKT). This data release contains 3 zipped folders, EKF_ERTSS_results.zip that contains EKF and ERTSS groundwater flux estimates, Temperature_observations.zip that contains raw observed temperature time series, and Pressure_data.zip that contains raw observations of pressure from piezometers adjacent to vertical temperature profilers. Additionally, water pressure transducers (Onset HOBO model U20L) were suspended at two depths within 2" steel pipes with 20cm screen drivepoints that were driven vertically into bed sediments adjacent to locations TX129 and TX132.

These thermal infrared data (images and radiometric video) were collected with a FLIR T540 Thermal Camera with the following manufacturer specifications: Resolution: 464 × 348 pixels Spectral range: 7.5 - 14 µm Thermal sensitivity: less than 50 mK, 14° @ 30°C (86°F) Accuracy: ±2°C (±3.6°F) or ±2% of reading. All temperature measurements should be interpreted as 'apparent' as the thermal parameters of the camera have been set to assumed values for water and may not apply to reflected radiation off the water surface or other types of materials such as grass and sand. For the identification of possible groundwater discharge zones, relatively cold areas during warm days are investigated further with direct measurements. These data are for demonstration purposes only. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government

This data release contains field measurements of shallow sediment and seawater temperatures near the shoreline at Hen Cove, Pocasset, Massachusetts. The measurements were made on August 16, 2022 by the U.S. Geological Survey (USGS) to evaluate where groundwater/surface-water exchange was occurring at Hen Cove.

Quantification of mobile/less-mobile porosity dynamics at the sediment/water interface is critical to predicting contaminant storage, release, and transformation processes. Zones in groundwater flow-through lakes where lake water recharges the aquifer can strongly control aquifer water quality. Less-mobile porosity has previously been characterized in aquifers using flow path scale (10's of m+) tracer injections which are analyzed using numerical models. Methodology was recently developed to couple geoelectric measurements (bulk electrical conductivity, EC), which are directly sensitive to less-mobile ionic tracer exchange processes, with pumped fluid EC tracer data over time. If the fluid EC concentration history is assumed to reflect the more mobile porosity exchange processes, these paired fluid and bulk EC measurements can be used to quantify less-mobile porosity exchange in discrete cm-scale packets of sediment at the interface between surface and groundwater. For this study, tracer experiments were conducted in multiple rate-controlled downward flow experiments over several days. Although the bed was composed predominantly of highly permeable sands and gravels, which is not an intuitive sediment texture for less-mobile porosity, embedded cobbles created areas of less-mobile flow zones proximal to large cobbles. These experimental findings are described in detail in the associated publication: Briggs, M.A., Day-Lewis, F.D., Dehkordy, F.M.P., Hampton, T., Zarnetske, J.P., Singha, K., Harvey, J.W. and Lane, J.W.(2018), Direct observations of hydrologic exchange occurring with less-mobile porosity and the development of anoxic microzones in sandy lakebed sediments, Water Resources Research, DOI:10.1029/2018WR022823.

Quantification of mobile/less-mobile porosity dynamics at the sediment/water interface is critical to predicting contaminant storage, release, and transformation processes. Zones in groundwater flow-through lakes where lake water recharges the aquifer can strongly control aquifer water quality. Less-mobile porosity has previously been characterized in aquifers using flow path scale (10's of m+) tracer injections which are analyzed using numerical models. Methodology was recently developed to couple geoelectric measurements (bulk electrical conductivity, EC), which are directly sensitive to less-mobile ionic tracer exchange processes, with pumped fluid EC tracer data over time. If the fluid EC concentration history is assumed to reflect the more mobile porosity exchange processes, these paired fluid and bulk EC measurements can be used to quantify less-mobile porosity exchange in discrete cm-scale packets of sediment at the interface between surface and groundwater. For this study, tracer experiments were conducted in multiple rate-controlled downward flow experiments over several days. Although the bed was composed predominantly of highly permeable sands and gravels, which is not an intuitive sediment texture for less-mobile porosity, embedded cobbles created areas of less-mobile flow zones proximal to large cobbles. These experimental findings are described in detail in the associated publication: Briggs, M.A., Day-Lewis, F.D., Dehkordy, F.M.P., Hampton, T., Zarnetske, J.P., Singha, K., Harvey, J.W. and Lane, J.W.(2018), Direct observations of hydrologic exchange occurring with less-mobile porosity and the development of anoxic microzones in sandy lakebed sediments, Water Resources Research, DOI:10.1029/2018WR022823.

In summer in Massachusetts, USA, preferential groundwater discharge zones are often colder than adjacent streambed areas that do not have substantial discharge. Therefore, discharge zones can efficiently be identified and mapped over space using heat as a tracer. This data release contains fiber-optic distributed temperature sensing (FO-DTS) data collected along the streambed interface of the main channel and tributaries of the upper Quashnet River, within approximately 1 km of Johns Pond, from June 14 to June 20, 2020. For these deployments a Salixa XT-DTS control unit (Salixa Ltd, Hertfordshire, UK) was used, and measurements were made over several day increments at 0.508 m linear resolution. Specific locations for collected data are located within the data files, and additional details are contained in the ‘readme’ files within each zipped data directory. Measured data in the form of Salixa instrument files are located in the 'Raw' data directory, including data collected along lengths of optical fiber that were not installed in the streams. The 'Processed' data directory contains data that have been aggregated from the original machine output files, spatially trimmed, and georeferenced. Additionally, simple summary streambed interface temperature statistics (mean, max, min, standard deviation) are listed by streambed location.

This data release contains electrical resistivity tomography (ERT) and frequency domain electromagnetic (FDEM) data collected in areas of unwalled shoreline at the Bremerton Naval Complex, WA, June 1-5, 2023. Preliminary inverse results from the FDEM data area also included. Two sites were investigated: Charleston Beach and Segment 4. Charleston Beach is a gently sloping pebble beach adjacent to the naval complex; whereas Segment 4 is a steeply sloping section of rocky shoreline on the naval complex surrounded by a pier and naval complex infrastructure. At Charleston Beach, FDEM data were collected with two different instruments with different sensitivity patterns (a DualEM-421 and a GEM-2) during negative tide (less than the mean low tide level) on June 2,2023. At Segment 4, various time-lapse ERT configurations were tested during June 3-5 over tidal cycles, while FDEM datasets (GEM-2 only) were collected during negative tides over this period. To facilitate comparison of geophysical data with tides, tide elevation predictions from NOAA station 9445958 are included in this release. A local digital elevation model was also created for Segment 4 using a real time kinematic (RTK) global positioning system.