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Zachary C Johnson

Research Hydrologist
Email: zjohnson@usgs.gov
Office Phone: 253-552-1681
ORCID: 0000-0002-0149-5223
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The U.S. Geological Survey (USGS) Water Resources Mission Area (WMA) is working to address a need to understand where the Nation is experiencing water shortages or surpluses relative to the demand for water need by delivering routine assessments of water supply and demand and an understanding of the natural and human factors affecting the balance between supply and demand. A key part of these national assessments is identifying long-term trends in water availability, including groundwater and surface water quantity, quality, and use. This data release contains Mann-Kendall monotonic trend analyses for 18 observed annual and monthly streamflow metrics at 6,347 U.S. Geological Survey streamgages located in the conterminous...
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The U.S. Geological Survey (USGS) Water Resources Mission Area (WMA) is working to address a need to understand where the Nation is experiencing water shortages or surpluses relative to the demand by delivering routine assessments of water supply and demand. A key part of these national assessments is identifying long-term trends in water availability, including groundwater and surface water quantity, quality, and use. This data release contains Mann-Kendall monotonic trend analyses for annual groundwater metrics at 39,964 wells located in the conterminous United States, Alaska, Hawaii, and Puerto Rico. The groundwater metrics include annual mean, maximum, and minimum water level and the timing of the annual...
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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...
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A combination of long-term daily temperature records and depth to bedrock measurements were used to parameterize one-dimensional models of shallow aquifer vertical heat transport in Shenandoah National Park, VA, USA. Spatially discontinuous roving water surface and bank temperatures surveys were performed with a handheld thermal infrared camera in September and December 2015 along the main channel of a headwater stream supporting coldwater-dependent brook trout (Salvelinus fontinalis). We also installed vertical arrays of thermal data loggers to estimate bulk thermal diffusivity of the saturated alluvium at two stations in the upper trout section. The methods are fully documented in the associated journal article,...
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The U.S. Geological Survey (USGS) Water Mission Area (WMA) is working to address a need to understand where the Nation is experiencing water shortages or surpluses relative to the demand for water need by delivering routine assessments of water supply and demand. It is also improving understanding of the natural and human factors affecting the balance between supply and demand. A key part of these national assessments is identifying long-term trends in water availability, including groundwater and surface water quantity, quality, and use. To describe the long-term trends in the surface water quality component of water availability, data from the USGS and other Federal, State, and local agencies were accessed primarily...
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