MODFLOW is the code developed by the USGS for the simulation of groundwater flow in steady and transient flow conditions. MODFLOW can represent a wide variety of physical process related to the groundwater flow regime as recharge, evapotranspiration, wells, among others. Latest development in MODFLOW allows the simulation of flow and transport in the unsaturated flow zone with the UZF and MT3D packages.

MODFLOW can simulate different time scales related to the groundwater flow requirements or period of study. A transient simulation can last:

hours on pumping test analysis
months for a baseflow recession calibration
years for a groundwater balance
decades for a mine closure assessment
centuries for simulation of climate change and glaciation periods

This tutorial deals with the simulation of the groundwater flow regimen after the implementation of mine closure options as soil/geomembrane cover above a Tailings Storage Facility (TSF) over a period of 80 years with results every 4 years. The tutorial deal with a full steady flow model which have been implemented to transient conditions on the model configuration and boundary conditions. A discussion of the seepage with time and final conditions after closure is presented to analyse the efficiency of the closure techniques.