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Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.
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Archive of boomer subbottom data collected during USGS cruise ATSV99045, northern North Carolina, October 9-27, 1999
No abstract available.
Archive of chirp subbottom data collected during USGS cruise ATSV99045, northern North Carolina, October 9-27, 1999
No abstract available.
Archive of seismic-reflection data collected during USGS cruise Lake Mead 01007 in Lake Mead, Nevada and Arizona, 1-28 April, 2001
No abstract available.
Archive of seismic-reflection data collected during USGS cruise Lake Mead 99014 in Lake Mead - Nevada and Arizona, 14-25 May, 1999
No abstract available.
Archive of Boomer subbottom data collected during USGS Cruise RAFA01025, Choptank River, Maryland, March 6-9, 2001
No abstract available.
Archive of Chirp subbottom data collected during USGS Cruise RAFA01025, Choptank River, Maryland, March 6-9, 2001
No abstract available.
Geology and coal resources of the Gulnare, Cuchara Pass, and Stonewall area, Huerfano and Las Animas Counties, Colorado
No abstract available.
Comparison of water quality in shallow groundwater near agricultural areas in the Delaware Coastal Plain, 2014 and 2019
The State of Delaware has encouraged agricultural conservation practices to improve nutrient uptake by crops and mitigate nutrient transport to groundwater in the surficial aquifer. To study recent changes in groundwater quality, the U.S. Geological Survey and the Delaware Department of Agriculture (DDA) developed a network of shallow wells near agricultural areas throughout the Delaware Coastal Plain. This network was designed to characterize water quality related to agricultural practices and to detect any recent changes in shallow groundwater quality, in particular groundwater nitrate concentrations. The shallow well network was first sampled in 2014 and resampled in 2019. In 2019, field parameters (including dissolved oxygen, pH, specific conductance, and temperature), major ions, nutrients, stable isotopes of water, and isotopes of nitrate were measured in groundwater samples collected between October and December. Wells were organized into three groups based on their geochemical characteristics measured in 2014: the Agricultural, Urban, and Mixed Groups. Results from the 2019 sampling showed little change in water quality from the 2014 sampling. Land-use factors continued to be the driving influence between groups. Groundwater moves slowly and changes in groundwater quality are likely to respond slowly to changes in conservation practices. Continued sampling of both groundwater quality in this network and monitoring land management practices can help detect groundwater quality trends in the future.
Archive of sidescan-sonar data collected off the North Carolina coast during USGS cruise ATSV99045, 7-27 October, 1999
No abstract available.
Preliminary description of a model of ground-water flow and ground-water/surface-water interaction for predevelopment , 1941-50, and 1950-97 development conditions in part of the Republican River Basin, Nebraska, Kansas, and Colorado as of April 26, 2002
No abstract available.
Global performance of remote sensing-based and reanalysis-driven models to estimate open water evaporation
Evaporation plays an essential role in the water cycle, influencing local and regional climates while directly impacting water availability in lakes. However, directly measuring evaporation over water bodies remains challenging due to the high costs of installing and maintaining the required in situ instrumentation. Although several remote sensing algorithms have been providing evaporation estimates, the lack of a global validation hinders our understanding of their relative uncertainties and performances across different regions. Here, we analyze the performance of a suite of models that leverage satellite data and meteorological reanalysis to estimate evaporation over lakes worldwide. We compare 3 remote sensing-based models, 1 reanalysis-driven model and 1 ensemble approach, using in situ observations from 27 lakes representing a diverse range of geographic and climatic regions. Our results demonstrate that, overall, the ensemble outperformed any individual model in terms of accuracy, with a RMSE and a bias of 1.3 and 0.3 mm day −1 , respectively. These findings highlight the benefits of using an ensemble approach to estimate open water evaporation with satellite-based models at the global scale, leveraging the unique strengths of each model. For the individual models, differences in the representation of heat storage changes and advection effects led to lower values of RMSE and bias, depending on the location and depth of the lakes. This study sets the path for future improvement of open water evaporation algorithms globally, while remote sensing techniques are proven satisfactory to monitoring of water loss in lakes globally, an essential step toward effective large-scale water resources management.
Guidelines for collection and field analysis of ground-water samples for selected unstable constituents
The unstable nature of many chemical and physical constituents in ground water requires special collection procedures and field analysis immediately after collection. This report describes the techniques and equipment commonly used in the collection and field analysis of samples for pH, temperature, carbonate, bicarbonate, specific conductance, Eh, and dissolved oxygen.