The Neversink River watershed (above the Neversink Reservoir) has been a focus of U.S. Geological Survey (USGS) research regarding stream geochemistry, acidification, and ecology dynamics for decades. In 2019, the Water Mission Area Next Generation Water Observing Systems Program augmented the existing stream gage network there, including instrumentation to specifically characterize various aspects of groundwater discharge to streams. An important control on the spatiotemporal dynamics of groundwater discharge can be stream valley corridor depth to bedrock, otherwise conceptualized as the thickness of unconsolidated sediments sediments over the contiguous bedrock interface. In June 2019, and November 2020, passive seismic recordings were acquired at locations directly along stream banks in the Neversink River watershed, using MOHO Tromino Model TEP-3C (MOHO, S.R.L.) three-component seismometers to assess depth to bedrock using the horizontal-to-vertical spectral-ratio (HVSR) method. Resonance frequencies were derived from the raw data using the GRILLA software (MOHO, S.R.L.) and converted to inferred depths to the bedrock contact. This method requires a value for seismic shear wave velocity, which depends on the unconsolidated sediment composition and density, for the conversion of HVSR measured resonance frequency to a depth to bedrock. Possible shear wave velocities were estimated for Neversink River watershed sediment based on previous research in the glacial terrain of the Northeast USA, providing a range of possible data interpretations as shown in the ‘Processed_Data’ folder of this data release. We expect to update the release in the future as additional HVSR data are collected.

This data release documents streambed sediment thickness in the Neversink watershed (NY) as determined by field observations and HVSR passive seismic measurements, and were collected as an extension of a previous data set collected in the same watershed (see Associated Items). These measurements were made between May 17, 2021 and May 21, 2021 using MOHO Tromino three-component seismometers (MOHO, S.R.L.). Seismic observations were converted to sediment thickness (depth to bedrock, meters) using the horizontal-to-vertical spectral ratio (HVSR) method. Resonance frequencies were determined from time domain data using GRILLA (MOHO, S.R.L.) software and converted to inferred depth to bedrock for a range of possible values for sediment shear wave velocity, as determined from field observations, ground truthing, and previous studies in similar sediment types.

Using the horizontal-to-vertical spectral-ratio (HVSR) method, we inferred the depth to bedrock at the Slate River Floodplain, CO, USA. The point-scale passive seismic data were collected using Model TEP-3C Tromino seismometers over 20 min or less intervals with the instruments coupled directly to the floodplain ground surface at 42 non-flooded locations during June 2021. The ratio of horizontal-to-vertical Fourier spectra (HVSR), determined using Grilla software (MOHO, S.R.L.), along with the estimated sediment shear-wave velocity, was used to calculate the depth to the bedrock contact. This passive seismic dataset indicates that the deepest bedrock is 16 m below the surface, while the bedrock reaches the surface at the hillslope. This release contains the inferred bedrock depths based on likely shear wave velocities (Vs) intrinsic to the underlying sediment, ranging from 300 m/s to 400 m/s, listed in the processed_data subdirectory in the file 'SLAC_HVSR_June2021.csv.' The range of possible depth to bedrock interpretations is included for demonstration purposes only.

Digital hydrogeologic datasets were developed for the Rondout-Neversink study area in upstate New York in cooperation with the New York State Department of Environmental Conservation. These datasets define the hydrogeologic framework of the valley-fill aquifer and surrounding till-covered uplands within the study area. Datasets include: bedrock elevation raster, lacustrine silt and clay top and bottom elevation rasters, LIDAR minimum elevation raster, lacustrine extent polygon, valley-fill extent polygon, and surficial geology polygons. Elevation layers were interpolated at 125-foot discretization to match the model grid cell size.

This dataset consists of a raster and surficial shapefiles for the Neversink River watershed, NY, that were generated using ArcGIS Pro's deep learning functionality. The shapefiles contain polygons that show the locations of shallow-to-exposed bedrock and alluvium-filled valleys, while the raster provides estimated minimum sediment thicknesses in the areas between the shallow/exposed bedrock and alluvium-filled valleys. The deep learning model that generated shallow/exposed bedrock and alluvium polygons was trained on existing geologic maps of New York and Pennsylvania. Minimum sediment thicknesses were estimated by applying an inverse distance weighting interpolation to measurements of stream incision depth and edges of shallow/exposed bedrock zones (where sediment thickness ≈ 0 m). In this area, stream incision through bedrock was considered negligible. The interpolation used variable numbers of points, a fixed interpolation distance of 250 m, and an output resolution of 30 m/pixel. Given the possibility that streams may have not completely incised through surficial materials down to bedrock, these estimates are minimum constraints on the true thicknesses of surficial sediments.

A total of 119 passive seismic soundings were collected with Tromino (MoHo s.r.l.) 3-axis seismometers in the Fountain Creek area to partially refine alluvial aquifer thickness (depth to bedrock) estimates, particularly over known or suspected paleochannels. Data were collected during June 21-24, 2021 with a team of 4-5 people, each equipped with a Tromino Blu or Tromino 3G passive seismometer. A subset of the data included measurements made for shear velocity calibration; this included data collected at 10 well sites where depth to bedrock was available from driller's logs, and 3 sites above cutbanks where bedrock outcropped and the thickness of alluvial sediments could be directly measured. Data were processed using a publicly available batch R processing script (Terry, 2022). In picking depths from the 119 measurements for alluvial aquifer thickness, roughly 30% were deemed unusable, 14% were picked with low confidence, 38% were picked with medium confidence, and 18% were picked with high confidence. Calibration data suggested a shear wave velocity of 195 meters per second. Using this value, estimated alluvial aquifer thicknesses ranged from 1.7 to 26.8 meters.

In July 2016, July 2019, and March 2020, 318 seismic recordings were acquired at locations within Shenandoah National Park, Virginia, using MOHO Tromino Model TEP-3C three-component seismometers to assess depth to bedrock using the HVSR method. This method requires a measurement of estimate of shear wave velocity, which depends on the regolith sediment composition and density, for the conversion of measured resonance frequency to a depth to bedrock. Shear wave velocities were calculated for sediment in Shenandoah NP at locations where regolith thickness is known (e.g. at documented boreholes). The locations in this study were generally selected to characterize the depths to bedrock adjacent to streams monitored for coupled temperature and flow dynamics related to several ongoing USGS projects.

In October and November of 2016 and 2017, the U.S. Geological Survey collected horizontal-to-vertical spectral ratio (HVSR) data at 104 sites in the Genesee Valley, Livingston County, New York as part of a saline-groundwater investigation in cooperation with the New York State Department of Environmental Resources. The HVSR technique, commonly referred to as the passive-seismic method, is used to estimate the thickness of unconsolidated sediments and the depth to bedrock (Lane and others, 2008). The passive-seismic method uses a single, broad-band three-component (two horizontal and one vertical) seismometer to record ambient seismic noise. In areas that have a strong acoustic contrast between the bedrock and overlying sediments, the seismic noise induces resonance at frequencies that range from about 0.3 to 40 hertz (Hz). The ratio of the average horizontal-to-vertical spectrums produces a spectral-ratio curve with peaks at fundamental and higher-order resonance frequencies. The spectral ratio curve (the ratio of the averaged horizontal-to-vertical component spectrums) is used to determine the fundamental resonance frequency that can be used along with an average shear-wave velocity or a power-law regression equation to estimate sediment thickness and depth to bedrock (Lane and others, 2008; Brown and others, 2013; Chandler and others, 2014; and Johnson and Lane, 2016). The HVSR data presented in this data release were collected at each site for 30 minutes using a Tromino Model TEP-3C three-component seismometer (1). The data were processed with Grilla 2011 version. 6.1 software1 to 1) remove anthropogenic noise, 2) convert the time-domain data to frequency domain, 3) compute and plot the spectral ratio curve, and 4) determine the resonance frequency. This data release presents the resonance frequency peaks identified from the HVSR measurements. Also presented are reported depth-to-bedrock data for wells located at or near HVSR data-collection sites in the Genesee Valley for use in the development of a local regression equation that relates the resonance frequency peak to the depth to bedrock. Raw HVSR data for each HVSR measurement are presented in the attached. The HVSR data-collection sites are designated by a county sequential numbering system (LVHVSR1, LVHVSR2, etc. where LV indicates Livingston County). Additional HVSR measurements at a HVSR data-collection site are indicated by a sequential number extension (LVHVSR27.01, LVHVSR27.02, etc.). (1) Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. References Brown, C.J., Voytek, E.B., Lane, J.W., Jr., and Stone, J.R., 2013, Mapping bedrock surface contours using the horizontal-to-vertical spectral ratio (HVSR) method near the middle quarter area, Woodbury, Connecticut: U.S. Geological Survey Open-File Report 2013–1028, 4 p., available at http://pubs.usgs.gov/of/2013/1028. Chandler, V. W., and Lively, R. S., 2014, Evaluation of the horizontal-to-vertical spectral ratio (HVSR) passive seismic method for estimating the thickness of Quaternary deposits in Minnesota and adjacent parts of Wisconsin: Minnesota Geological Survey Open File Report 14-01, 52 p. Johnson, C. D. and Lane, J. W., 2016, Statistical comparison of methods for estimating sediment thickness from horizontal-to-vertical spectral ratio (HVSR) seismic methods: An example from Tylerville, Connecticut, USA, in Symposium on the Application of Geophysics to Engineering and Environmental Problems Proceedings: Denver, Colorado, Environmental and Engineering Geophysical Society, pp. 317-323. https://doi.org/10.4133/SAGEEP.29-057 Lane, J.W., Jr., White, E.A., Steele, G.V., and Cannia, J.C., 2008, Estimation of bedrock depth using the horizontal-to-vertical (H/V) ambient-noise seismic method, in Symposium on the Application of Geophysics to Engineering and Environmental Problems Proceedings: Denver, Colorado, Environmental and Engineering

A combination of long-term daily temperature records and depth to bedrock measurements were used to parametrize one-dimensional models of shallow aquifer vertical heat transport in Shenandoah National Park, VA, USA. 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 employed rapid, cost-effective passive seismic measurements to evaluate the variable thickness of the shallow colluvial and alluvial aquifer sediments along a headwater stream supporting coldwater-dependent brook trout (Salvelinus fontinalis) in Shenandoah National Park. The methods are fully documented in the associated journal article, Briggs, M.A., J.W. Lane, C.D. Snyder, E.A. White, Z.C. Johnson, D.L. Nelms, and N.P. Hitt, 2017, Shallow mountain bedrock limits seepage-based headwater climate refugia, Limnologica, https://dx.doi.org/10.1016/j.limno.2017.02.005. This Data Release includes seismic data collected as part of the study.

From 2013 to 2015, bathymetric surveys of New York City’s six West of Hudson reservoirs (Ashokan, Cannonsville, Neversink, Pepacton, Rondout, and Schoharie) were performed to provide updated capacity tables and bathymetric maps. Depths were surveyed with a single-beam echo sounder and real-time kinematic global positioning system (RTK-GPS) along planned transects at predetermined intervals for each reservoir. A separate set of echo sounder data was collected along transects at oblique angles to the main transects for accuracy assessment. Field survey data was combined with water-surface elevations in a geographic information system to create three-dimensional surfaces representing reservoir-bed elevations in the form of triangulated irregular networks (TINs); the TINs were linearly enforced to better represent geomorphic features within the reservoirs. The linearly enforced TINs were used to create bathymetric maps of the reservoirs; contours were mapped at 2-foot intervals and capacity was calculated at 0.01-foot intervals.