David P. Ahlfeld

Publication Date



The objective of this study is to test different formations with a new optimization program. The area under study is located close to Los Angeles, and it has experienced a large drawdown of the water table, with related subsidence. The analyses utilizes Ground Water Management (GWM), a public domain code distributed by the USGS as a process within MODFLOW 2000. The different algorithms within GWM were tested with a large-scale transient unconfined system. The different analysis allowed the verification of the program. In this application, GWM is used to optimize the resources, and the MODFLOW packages from the LANOPT Model are used to simulate the system.

Several tests were pe1formed with two main motives. One intended to test the mathematical responses of the program, while the second one created different formulation approaches to manage the aquifer. The mathematical responses of the program were tested with a sensitivity analysis of the parameters that defined how the formulation was solved. The second part of the analysis was done by creating different management strategies, by changing the price of injection, and the bounds on head. Two different formulations were used to optimize the system. One maximizes the pumping rates while constraining the head elevation of the aquifer. The second one optimizes the maximum minimum head that can be achieved after meeting the demand constraints.

The overall performance of the GWM program proved the model’s ability to optimize a large-scale transient problem. Both formulations yielded results that portray the accurate functioning of the program.