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Documentation for the State Variables Package for the Groundwater-Management Process of MODFLOW-2005 (GWM-2005)

David P. Ahlfeld·Paul M. Barlow·Kristine M. Baker
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Abstract

Many groundwater-management problems are concerned with the control of one or more variables that reflect the state of a groundwater-flow system or a coupled groundwater/surface-water system. These system state variables include the distribution of heads within an aquifer, streamflow rates within a hydraulically connected stream, and flow rates into or out of aquifer storage. This report documents the new State Variables Package for the Groundwater-Management Process of MODFLOW-2005 (GWM-2005). The new package provides a means to explicitly represent heads, streamflows, and changes in aquifer storage as state variables in a GWM-2005 simulation. The availability of these state variables makes it possible to include system state in the objective function and enhances existing capabilities for constructing constraint sets for a groundwater-management formulation. The new package can be used to address groundwater-management problems such as the determination of withdrawal strategies that meet water-supply demands while simultaneously maximizing heads or streamflows, or minimizing changes in aquifer storage. Four sample problems are provided to demonstrate use of the new package for typical groundwater-management applications.

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David P. Ahlfeld, Paul M. Barlow, Kristine M. Baker. 2011. Documentation for the State Variables Package for the Groundwater-Management Process of MODFLOW-2005 (GWM-2005). https://doi.org/10.3133/tm6a36

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