Wednesday, January 15, 2020

MODFLOW and More 2019 – Using AEM as a Stepwise Tool for Analyzing Flow in Fractured Bedrock

Last June, several members of the McLane Environmental/flexAEM team attended and presented at the MODFLOW and More Conference at the Integrated Groundwater Modeling Center (IGWMC) at the Colorado School of Mines in Golden, Colorado.  Those presentations included two talks on AEM modeling, which were part of “The Analytic Element to the Rescue: Developments and Applications” session, chaired by AEM pioneers Henk Haitjema and Otto Strack.  Now, one of those talks, which illustrated how AEM can be utilized as a stepwise tool for analyzing flow in fractured bedrock aquifers, can be viewed HERE.

As described in the video, analysis of groundwater flow in fractured bedrock aquifers may be performed using a spectrum of modeling approaches that includes (in general order of complexity) analytic solutions; analytic element method (AEM) models; numerical (FD / FE) models with few discrete fractures/faults; and discrete fracture network (DFN) models with many (often stochastically generated) fractures. On that analysis spectrum, AEM models offer a number of advantages, including allowing the modeler to:
  • Build on a selected analytic solution
  • Move beyond the analytic solution to create a more useable model framework that incorporates other hydraulic and hydrologic features for site analyses
  • Represent any fracture or fault geometry and orientation without problems of cutting across or excessively refining the grid, because there is no grid!
  • Examine the flow field on scales from inches (near a fracture or fault) to miles (in the far field)
  • Use insight gained to develop a more complex numerical model if required.

The current study described in the video shows techniques for using AEM models to analyze pumping tests in wells fed by a fracture or fault; using fracture elements to explicitly represent the discrete fracture features that cause anisotropy in fractured rock aquifers; and analyzing pathways in natural and pumping-influenced flow fields in fractured and faulted bedrock aquifers.

To learn more, check out our Example Application Page on this topic, or Contact Us with any questions.