UM-7: Finite Element Aquifer Flow Model

Abstract

The purpose of this report is to describe how to model aquifer systems with AQUIFEM-1, a finite element aquifer flow model developed by Massachusetts Institute of Technology and implemented at the Institute for regional aquifer studies. The model has been very versatile and can be used for 2 dimensional groundwater flow problems. It is based on the hydraulic equations defining the horizontal flow but it can also be used for the analysis of vertical cross sectional flows as well. GaIerkine finite element technique for linear interpolation function and basic triangular elements are employed in this model. Leakage from adjacent aquifer, pumping wells, lateral inflows and outflows, flowing wells, infiltration, evapotranspiration, rising water conditions and numerous other conditions are accounted. The model can be used both for steady state and transient flow problems for confined, unconfined or changing status aquifers.

Since the original manual prepared by MIT includes detailed mathematical formulation of the model, the same is not presented here. The input data are automatically checked for consistency and completeness and wherever necessary proper messages are generated. Output which can be printed, or saved on a file, includes a mimik of input and at each time step, heads, drawdowns, flow rates, optimal fluxes, aquifer status etc. CROUTES algorithm is used for solving the equations. The detailed list of variables and description of input data requirements are presented.