Techniques and Methods 6–A47
Many groundwater wells are open to multiple aquifers or to multiple intervals within a single aquifer. These types of wells can be represented in numerical simulations of groundwater flow by use of the Multi-Node Well (MNW) Packages developed for the U.S. Geological Survey’s MODFLOW model. However, previous versions of the Groundwater-Management (GWM) Process for MODFLOW did not allow the use of multi-node wells in groundwater-management formulations. This report describes modifications to the MODFLOW–2005 version of the GWM Process (GWM–2005) to provide for such use with the MNW2 Package. Multi-node wells can be incorporated into a management formulation as flow-rate decision variables for which optimal withdrawal or injection rates will be determined as part of the GWM–2005 solution process. In addition, the heads within multi-node wells can be used as head-type state variables, and, in that capacity, be included in the objective function or constraint set of a management formulation. Simple head bounds also can be defined to constrain water levels at multi-node wells. The report provides instructions for including multi-node wells in the GWM–2005 data-input files and a sample problem that demonstrates use of multi-node wells in a typical groundwater-management problem.
First posted September 25, 2013
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Ahlfeld, D.P., and Barlow, P.M., 2013, Use of multi-node wells in the Groundwater-Management Process of MODFLOW–2005 (GWM–2005): U.S. Geological Survey Techniques and Methods, book 6, chap. A47, 26 p., https://pubs.usgs.gov/tm/06/a47/.
Multi-Node Wells in Management Formulations
Sample Problem: MNW–Supply
Impact of Multi-Node Wells on the GWM Algorithm
Appendix 1. Input Instructions for Use of MNW-Type Wells in a GWM Formulation