Filters: Tags: MODPATH6 (X)
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A steady state three-dimensional groundwater flow (MODFLOW-2005) and advective transport (MODPATH6) model was developed to examine subsurface travel times to wells and receiving streams in two subcatchments contributing to the Upper Chester River, Maryland. The model was calibrated to conditions from 1990 to 2005, the period for which groundwater levels, stream discharge measurements, and atmospheric tracer measurements were jointly available. Six calibrated model scenarios were generated and paired with First Order Second Moment (FOSM) linear uncertainty analysis tools to evaluate (i) the uncertainty of base-flow age estimates as well as (ii) the worth of future data collection. The development of the model input...
A three-dimensional groundwater flow model was developed to simulate the effects of withdrawals on the groundwater-flow systems of five aquifers in and around Ocean County, New Jersey—the unconfined Kirkwood-Cohansey aquifer system and Vincentown aquifer, and three confined aquifers--the Rio Grande water-bearing zone, the Atlantic City 800-foot sand, and the Piney Point aquifer. A transient model was used to simulate conditions that represent no groundwater withdrawals, 2000–2003 groundwater withdrawals, and maximum-allocation groundwater withdrawals. Particle-tracking analysis, using results from two steady-state simulations, determine flow paths and travel times to near-shore wells screened in the unconfined Kirkwood-Cohansey...
This data release contains model simulation results of a particle tracking analysis to delineate areas that provide recharge to surface waters and public-supply wells on Long Island, NY. The analysis partitions the recharge areas based on particle travel times of greater than or less than 10 years to reach the receiving surface water or well. The simulation was performed using a regional-scale numerical model of the Long Island aquifer system (Walter and others, 2020a and 2020b) for average 2005-2015 conditions. The model implements MODFLOW-NWT (Niswonger and others, 2011) to represent steady-state groundwater pumping and aquifer recharge conditions; recharge areas were identified and partitioned using the particle-tracking...
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...
A previously developed steady state three-dimensional groundwater flow (MODFLOW-2005) and advective transport (MODPATH6) model was used to examine subsurface nitrate transport to wells and receiving streams in two subcatchments contributing to the Upper Chester River, Maryland. Multiple scenarios of flow and transport parameter fields (recharge, hydraulic conductivity, and porosity) were previously calibrated against groundwater levels, stream discharge measurements, and atmospheric tracer measurements, as described in https://doi.org/10.1016/j.jhydrol.2018.02.006; those multiple scenarios are also available as a USGS data release (https://doi.org/10.5066/F7SN087R). Two of the flow and transport scenarios calibrated...
In 2016, the United States Geological Survey (USGS) began development of a regional-scale numerical model of the Long Island aquifer system, as part of the National Water Quality Assessment (NAWQA) Program. The three-dimensional groundwater-flow model was developed to evaluate 1) responses of the hydrologic system to changes in natural and anthropogenic hydraulic stresses 2) the subsurface distribution of groundwater age, and 3) the regional-scale distribution of groundwater travel times and the source of water to fresh surface waters and coastal receiving waters. The model also provides the groundwater flow components used to define model boundaries for possible inset models used for local-scale analyses. Unconsolidated...
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...
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