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In cooperation with the U.S. Navy, USGS developed and calibrated a numerical MODFLOW 6 model to simulate regional groundwater flow under selected conditions during 1999-2017 at and near the former Willow Grove Naval Air Station Joint Reserve Base in Horsham, Montgomery County and the former Naval Air Warfare Center Warminster in Bucks County, Pennsylvania. The model simulations provide information on regional groundwater-flow paths and groundwater/surface-water exchanges, in relation to changes in water supply pumping and recharge rates. Groundwater flow paths were simulated using MODPATH 7 from possible PFAS sources at the former bases under steady-state conditions for years 1999, 2010, 2013, 2016, and 2017. This...
A regional groundwater-flow model and particle-tracking program were used to delineate areas contributing groundwater to coastal and freshwater bodies and to estimate travel times from the water table to saline water bodies under average conditions from 1968 to 1983 on Long Island, New York. The coastal waters of Long Island are important economic and recreational resources for the region. The coastal water bodies receive freshwater from inflow of both surface water and groundwater, in addition to tidal exchanges of saltwater. Excessive nitrogen inputs associated with development and urbanization in the freshwater recharge areas to coastal water bodies can adversely affect marine and estuarine ecosystems. The results...
MODFLOW-NWT groundwater flow models and MODPATH6 particle tracking simulations were developed to determine contributing areas (CAs) for and advective travel times to domestic wells under extreme recharge events in a small hypothetical watershed underlain by dipping sedimentary rocks. The hypothetical models are based on hydrogeologic conditions in the Newark Basin, located in New Jersey, New York, and Pennsylvania, USA. During extreme recharge events, groundwater supply wells have increased vulnerability to contaminants or pathogens originating at land surface that are flushed into the subsurface. Fractured-rock aquifers are particularly vulnerable because transport to wells can be very fast owing to preferential...
In 2004 U.S. Geological Survey biologists recorded vegetation and biological soil crust (BSC) cover by species as well as measured soil stability and compaction data along 85 transects at the Badger Wash study area in western Colorado. Soil samples were collected and processed for chemistry and texture. Using analysis of variance and nonmetric multidimensional scaling (NMDS) we assessed the cover of vegetation and BSC both grouped by plant physiognomy and dynamic soil properties (soil chemistry/nutrients and stability and compaction) as influenced by the effects of grazing history and soil group (which varied by slope, topographic wetness index and soil properties). Vegetation and BSC cover data were also compared...
A previously constructed numerical model (https://pubs.usgs.gov/pp/2007/1737a/) simulating the regional groundwater-flow system in the vicinity of the Wright-Patterson Air Force Base (WPAFB) near Dayton, Ohio, was updated to incorporate current hydrologic stresses and conditions and improve the usefulness of the model for water-supply planning and protection. The Great Miami Buried Valley Aquifer was designated a sole-source aquifer in 1988 and provides the supply for the substantial water use needs in the Dayton area. Hydrogeologic investigations of groundwater flow in the nearby WPAFB have been ongoing since the early 1990s, when the USGS first partnered with WPAFB to model groundwater flow near the Base in an...
A three-dimensional, groundwater-flow model (MODFLOW-2000) and a particle-tracking program (MODPATH5) were used to evaluate the effects of changes in pumping on regional groundwater-flow paths, 2005 and 2010, and areas contributing recharge to discharging wells, 1990-2010, in the vicinity of North Penn Area 7 Superfund site, Montgomery County, Pennsylvania. The steady-state model was used to simulate conditions for No Pumping, 1990, 2000, 2005, and 2010. The model was used to (1) evaluate the changes in flow paths from likely contaminant sources, and (2) delineate areas contributing recharge to streams and pumping wells. This USGS data release contains all of the input and output files for the simulations described...
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