Saltwater Intrusion in Coastal Aquifers

Using Visual MODFLOW and SEAWAT for Saltwater Intrusion Applications

Saltwater intrusion is defined as the inland movement of seawater into aquifers previously occupied by freshwater. The causes include: climate change, groundwater pumping, higher evapotranspiration, lower recharge, anthropogenic causes, urban development (buildings, pavement, sewers, etc.), channelization of wetlands, agricultural practices, natural causes, etc.

Figure 1: Saltwater intrusion in a coastal aquifer environment (Barlow, 2003)

In standard transport modeling (using MT3DMS), it is assumed that the solute is dilute and miscible (soluble within groundwater) and that solute density does not affect the groundwater flow behaviour. This is typical for groundwater contaminant plumes with small concentrations (i.e. < 1000 mg/L). However, when solute density differs from the density of water, the flow behaviour will be affected:

  • groundwater flow (advection, dispersion) moves solute concentration;
  • changes in concentration = changes in the equivalent freshwater head (EFH);
  • changes in head = changes in the groundwater flow regime.

Density is also a contributing factor in applications such as the transport of dense mine tailings/leachate, transport of sewage wastewater, and flow beneath brine storage ponds.

SEAWAT was developed to simulate 3-dimensional, variable-density, transient groundwater flow in porous media. SEAWAT is a combination of the USGS MODFLOW code and the MT3DMS code. Most Applications of saltwater intrusion will utilize the USGS SEAWAT code.  SEAWAT is currently only supported in the VMOD Classic interface.  If you require instructions on how to access this, please contact us.

Online References using Visual MODFLOW and SEAWAT

Investigation of seawater intrusion in the Recife coastal plain, Brazil
(Published in SWIM Proceedings)
BrazilCoastal aquifers
Measurement of Tidal Fluctuation Using MATLAB-Based Program and Development of Salinity Intrusion Model
for the Coastal Region of Bangladesh Using VISUAL MODFLOW
Bangladesh SEAWAT
Hydrogeological impact of wellpoint dewatering upon unconfined coastal aquifer of the municipality of Cervia (Ravenna – Italy)
Published in SWIM Proceedings
Challenges of modeling the impact of multi-purpose aquifer utilization on variable-density groundwater flowAustralia
The Influence of Three-dimensional Dune Topography on Salt Water Intrusion in Marina Romea, Italy:
A Numerical Modeling Study Using LIDAR Data
ublished in SWIM 2008 Proceedings
Numerical Simulation of Seawater Intrusion in Response
to Climate Change Impacts in North Gaza Coastal Aquifer Using SEAWAT
GazaCoastal Aquifers, SEAWAT,

climate change, sea level rise

A Modelling Study of Seawater Intrusion in the Liao Dong Bay Coastal Plain
(Published in Journal of Marine Science and Technology)
Numerical Modelling of Seawater Intrusion in Manukan Island’s Aquifer, Malaysia
(Published in World Applied Sciences Journal)
Saltwater Intrusion in the Coastal Aquifer of Gaza /Palestine: Concepts, Observations, Modeling, Prevention StrategiesGaza
Assessment of New Esna barrage impacts on groundwater and proposed measures
(Published in Water Science)
EgyptGroundwater rise; Surface water/groundwater interaction
Numerical Feasibility Study for Treated Wastewater Recharge as a Tool to Impede Saltwater Intrusion in the Coastal Aquifer of Gaza – PalestinePalestine
Simulation of Groundwater Flow at Beach Point, Cape Cod, Massachusetts, USAUSATidal Influences, Coastal Aquifers, Migration of Septic Effluent
Ground Water Modeling of Nellore Coastal Zone
(Published in International Journal of Civil, Structural, Environmental and Infrastructure Engineering Research and Development (IJCSEIERD))
Adaptation to the Impact of Sea Level Rise in the Nile Delta Coastal Zone, Egypt
(Published in Journal of American Science)
EgyptClimate change, seawater intrusion, SEAWAT


Note: Waterloo Hydrogeologic does not imply endorsement of software from the authors of these publications/reports

Learn More


  • Barlow, P.M. (2003) “Groundwater in Freshwater-Saltwater Environments of the Atlantic Coast”. USGS Circular 1262, United States Geological Survey, Reston, VA.