Tom Bulatewicz

Groundwater economics: An object‐oriented foundation for integrated studies of irrigated agricultural systems

[1] An integrated foundation is presented to study the impacts of external forcings on irrigated agricultural systems. Individually, models are presented that simulate groundwater hydrogeology and econometric farm level crop choices and irrigated water use. The natural association between groundwater wells and agricultural parcels is employed to couple these models using geographic information science technology and open modeling interface protocols. This approach is used to study the collective action problem of the common pool. Three different policies (existing, regulation, and incentive based) are studied in the semiarid grasslands overlying the Ogallala Aquifer in the central United States. Results show that while regulation using the prior appropriation doctrine and incentives using a water buy-back program may each achieve the same level of water savings across the study region, each policy has a different impact on spatial patterns of groundwater declines and farm level economic activity. This represents the first time that groundwater and econometric models of irrigated agriculture have been integrated at the well-parcel level and provides methods for scientific investigation of this coupled natural-human system. Results are useful for science to inform decision making and public policy debate.

The Simple Script Wrapper for OpenMI

Integrated environmental modeling enables the development of comprehensive simulations by compositing individual models within and across disciplines. The Simple Script Wrapper (SSW), developed here, provides a foundation for model linkages and integrated studies. The Open Modeling Interface (OpenMI) enables model integration but it is challenging to incorporate scripting languages commonly used for modeling and analysis such as MATLAB, Scilab, and Python. We have developed a general-purpose software component for the OpenMI that simplifies the linking of scripted models to other components. Our solution enables scientists to easily make their scripting language code linkable to OpenMI-compliant models fostering collaborative, interdisciplinary integrated modeling. The simplicity afforded by our solution is presented in a case study set in the context of irrigated agriculture. The software is available online as supplementary material and includes an example that may be followed to employ our methods.

A distributed data component for the Open Modeling Interface

As the volume of collected data continues to increase in the environmental sciences, so too does the need for effective means for accessing those data. We have developed an Open Modeling Interface (OpenMI) data component that retrieves input data for model components from environmental information systems and delivers output data to those systems. The adoption of standards for both model component input–output interfaces and web services make it possible for the component to be reconfigured for use with different linked models and various online systems. The data component employs three techniques tailored to the unique design of the OpenMI that enable efficient operation: caching, prefetching, and buffering, making it capable of scaling to large numbers of simultaneous simulations executing on a computational grid. We present the design of the component, an evaluation of its performance, and a case study demonstrating how it can be incorporated into modeling studies.

Accessible Parallelization for the Open Modeling Interface

As the availability of computing infrastructure continues to increase, so too does the need for accessible means for utilizing those resources. An effective approach is to enable desktop-oriented scientific software tools and frameworks to support execution on high performance cyberinfrastructure in a way that is transparent to the user. We have found this to be the case in our ongoing environmental modeling study in which we are applying multidisciplinary, integrated models to the study of a depleting aquifer. Our models are linked together using the Open Modeling Interface (OpenMI) which provides a composition framework for the sequential execution of model components. In this work we investigate the potential for incorporating parallelism into the OpenMI as a first-class citizen. We present a general solution in which model components may be executed in parallel without requiring changes to their source code. An alternate solution achieves greater parallelism through simultaneous invocations of individual components, but requires them to be modified in some cases. These can result in significant reductions in simulation runtimes on both multi-core desktop machines as well as in high performance computing environments. We demonstrate this potential speedup in a performance study in which the application of the general solution achieved 86% of linear speedup when executed on a high performance machine with 80 cores.