What is Groundwater Modeling and Why it is Important For Your Project?

Groundwater flow is not as mysterious as people make it out to be. In reality, the mathematics of how water flows in the subsurface is well established. While groundwater flow can be predicted, these predictions depend on numerous variables and complex equations. For this reason, groundwater experts rely on computer models to perform the necessary calculations. These predictions can be very valuable to municipalities and developers who need state or local permits for their construction project. Typically to obtain these permits, the regulatory agencies will want to make sure your project is not negatively impacting a nearby wetland or body of water, and neighboring wells. In many cases, groundwater modeling can prove your project will meet environmental permitting requirements, or provide insights to necessary design modifications ahead of the game.

What Can Be Evaluated with Groundwater Modeling?

While there are many uses for groundwater models, here are just a few common problems that can be evaluated with this technique:

Wastewater Disposal:

• How high will the groundwater mound under the disposal area?
• How long will it take for the effluent to reach a drinking water well?
• What will the concentration of nitrogen in the groundwater be when it reaches the property line?

Well Water Pumping

• Is that factory within the area of land that contributes water to the well?
• Will the withdrawal affect a nearby surface water body?

Groundwater Contamination

• Will the contamination plume reach a drinking water well?
• How long will it take for that chemical to reach a certain concentration at a given point?

How Groundwater Flow Models are Utilized:

1. To evaluate site impact, a baseline simulation is conducted, which establishes existing groundwater flow conditions.
2. A proposed simulation is conducted to predict the groundwater flow after the proposed project is constructed.

Differences between the results of the first and second models such as groundwater elevation, surface water elevation or streamflow volume quantify the potential impact of the proposed project. With this data, measures can be taken to lessen the impact, whether that requires reconfigurations to details of the project or overall redesign. For contamination projects, a second model is run that uses the results of the groundwater model and calculates the concentration distribution of dissolved chemicals.