Simulated Changes in Salinity in the York and Chickahominy Rivers from Projected Sea-Level Rise in Chesapeake Bay
The U.S. Geological Survey, along with the City of Newport News, evaluated the potential impacts of sea-level rise on the presence and degree of saltwater migration in Virginia tributaries of the Chesapeake Bay under multiple sea-level rise scenarios. The study utilized a hydrodynamic simulation model to evaluate potential changes in salinity in the York River and Chickahominy/James River estuaries. Simulated results demonstrate the potential for considerable salinity increases upstream with even marginal sea-level rise.
The methodologies developed as part of this study are transferable to other tributary basins to the bay. The results of this study can be expanded and refined to assess the effect of sea-level rise throughout the Chesapeake Bay estuary.
The study utilized numerical modeling to represent sea-level rise and the resulting hydrologic effects. Estuarine models for the two tributaries were developed and model simulations were made by use of the Three-Dimensional Hydrodynamic-Eutrophication Model (HEM-3D), developed by the Virginia Institute of Marine Science. HEM-3D was used to simulate tides, tidal currents, and salinity for Chesapeake Bay, the York River and the Chickahominy/James River. The model analyzed a no-rise scenario and three scenarios showing an increase of 30, 50, and 100 centimeters (cm).
The hydrodynamic models produced several results:
- Increases in mean salinity will greatly alter the existing water-quality gradients between the brackish water and fresh water. This is particularly important for the Chickahominy River, where a drinking-water-supply intake for the City of Newport News is located.
- In both estuaries, high freshwater river flow pushed migrating saltwater back toward Chesapeake Bay.
- Large increases in mean salinity are predicted for each sea-level rise scenario.
- The months of September and October have the most saline conditions, followed by July and August, with the least salinity in November and December. These results are consistent whether the year is wet, dry, or typical, and whether sea-level does not rise, or rises 30, 50, or 100 cm.
- For the 50-cm sea-level rise scenario on the York River, salinity migrated 6 km further upstream in a dry year than in a typical year. The same was true of the Chickahominy River for the 50-cm sea-level rise scenario but to a greater degree - salinity was detected 15 km further up the river in a dry year than in a typical year.
Publication Date: 2011
Authors or Affiliated Users:
- Karen C. Rice
- Mark R. Bennett
- Jian Shen
- The City of Newport News, Virginia
- U.S. Geological Survey (USGS)