Tar River Basin Model



Need for a Hydrologic Model

The Tar-Pamlico basin covers 5571 square miles of drainage area entirely within North Carolina. The basin supplies water to the population of nearly 415,000 [census 2010] residing in 16 counties within the basin.  Water use in the basin is almost evenly split between ground water and surface water sources.  The model only covers the Tar River portion of the basin.

A computer model is a needed tool for evaluating surface water resources management in the basin.  For long term planning, the State can use the model in making regulatory decisions by evaluating potential impacts of proposed projects with significant water withdrawals within the basin as well as interbasin transfer permit applications.  Local units of government as well as the State can use the model to plan for increased water use due to growth, and to evaluate the effects of operational and regulatory constraints during a drought condition.


OASIS, a patented, mass balance, water resources simulation/optimization model was developed for the Tar river basin. This basinwide model uses the finest practical geographic resolution and timestep.

OASIS 2010

The current version of the model includes hydrologic period from Jan 1930 to September 2009, and has water demand data for year 2010 as base case scenario and 50-year planning projection period scenarios from 2020 to 2060 for every 10-year interval. 

OASIS Model Development Document/Reports:

EFDC Model 2013

The Environmental Fluid Dynamics Code (EFDC) is a state-of-the-art hydrodynamic model that is used to simulate aquatic systems in one, two, and three dimensions.

EFDC Model Background Information:

Greenville Utilities Commission (GUC) signed a resolution in July 2012 to participate in the HB 609 process and partner with the NCDWR for the development of water supply alternatives to support the next GUC WTP expansion.  GUC developed the EFDC model as part of the Tar River Flow Study.   NCDWR's current focus will be on potential salinity impacts to GUC's water supply, with upstream movement of the freshwater / saltwater interface, especially under critical drought periods.

EFDC Model Development Documents and Reports


Contact Neelufa Sarwar (neelufa.sarwar@ncdenr.gov) or Pam Behm (pamela.behm@ncdenr.gov) to request access to the OASIS or EFDC model.

If you have a comment or question on the Tar plan/model, please contact us at dwr-tar-pam-staff@ncdenr.gov

Subscribe to the DWR Tar-Pamlico stakeholders email list: