Optimization techniques using MODFLOW-GWM
An important application of optimization codes such as MODFLOW-GWM is to maximize water supply from unconfined aquifers subject to constraints involving surface-water depletion and drawdown. In optimizing pumping for a fish hatchery in a bedrock aquifer system overlain by glacial deposits in eastern Wisconsin, various features of the GWM-2000 code were used to overcome difficulties associated with: 1) Non-linear response matrices caused by unconfined conditions and head-dependent boundaries; 2) Efficient selection of candidate well and drawdown constraint locations; and 3) Optimizing against water-level constraints inside pumping wells. Features of GWM-2000 were harnessed to test the effects of systematically varying the decision variables and constraints on the optimized solution for managing withdrawals. An important lesson of the procedure, similar to lessons learned in model calibration, is that the optimized outcome is non-unique, and depends on a range of choices open to the user. The modeler must balance the complexity of the numerical flow model used to represent the groundwater-flow system against the range of options (decision variables, objective functions, constraints) available for optimizing the model.
Citation Information
Publication Year | 2015 |
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Title | Optimization techniques using MODFLOW-GWM |
Authors | Anna Grava, Daniel T. Feinstein, Paul M. Barlow, Tullia Bonomi, Fabiola Buarne, Charles Dunning, Randall J. Hunt |
Publication Type | Conference Paper |
Publication Subtype | Conference Paper |
Index ID | 70194019 |
Record Source | USGS Publications Warehouse |
USGS Organization | Wisconsin Water Science Center |