Martijn J. Russcher Christian D. Langevin Eric D. Morway Richard R. McDonald Joseph D. Hughes 2022 <p><span>The MODFLOW&nbsp;</span><a class="topic-link" title="Learn more about API from ScienceDirect's AI-generated Topic Pages" href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/application-programming-interface" data-mce-href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/application-programming-interface">API</a><span>&nbsp;allows other programs to control MODFLOW and interactively change variables without having to modify the source code. The MODFLOW API is based on the Basic Model Interface (BMI), which is a set of conventions that define how to initialize a simulation, update the model state by advancing in time, and finalize the run. For many existing MODFLOW coupling applications, the information provided to MODFLOW must be updated multiple times in a time step. As this capability to modify variables within a time step is not defined by the BMI, an extension to BMI was developed. This eXtended Model Interface is part of the MODFLOW API and allows such a tight coupling to other models. Examples are included for a variety of use cases, including new flexibility for users to develop custom packages without modifying the MODFLOW source code and coupling MODFLOW with other models and optimization libraries.</span></p> application/pdf 10.1016/j.envsoft.2021.105257 en Elsevier The MODFLOW Application Programming Interface for simulationcontrol and software interoperability article