MODFLOW-NWT and MODPATH6 Used to Delineate Areas Contributing Groundwater and Travel Times to Receiving Waters in Kings, Queens, Nassau, and Suffolk Counties, New York

A previously developed three-dimensional steady-state groundwater flow model
(https://doi.org/10.3133/sir20205091) is used to assist resource managers and
planners in developing informed strategies to address nitrogen loading to coastal
water bodies of Long Island, New York. Coastal water bodies of Long Island are
important economic and recreational resources for the region. Therefore, the U.S.
Geological Survey and New York State Department of Environmental Conservation
initiated a program to delineate a comprehensive dataset of CAs (or areas
contributing groundwater), travel times, and groundwater discharges to streams,
lakes, marine-surface waters, and subsea discharge boundaries. The 25-layer
regional groundwater-flow model of average regional hydrologic conditions used
MODFLOW-NWT and MODPATH6 (for the particle-tracking analysis) to delineate
CAs to 843 water bodies. Two steady-state conditions were simulated: pre-pumping
conditions and recent conditions from 2005 to 2015. One hundred particles evenly
distributed across the top of each 500- by 500-foot model cell that receives recharge
at the water table, were tracked forward to discharge zones. This USGS data release
contains all of the input and output files for the simulations described in the associated
model documentation report (https://doi.org/10.3133/sir20215047).