Demonstrating Integrative, Scalable and Extensible Modeling of Hydrological Systems with Model-Based Systems Engineering and Hetero-functional Graph Theory

Abstract

Worsening global challenges demand solutions grounded in a systems-level understanding of coupled social and environmental dynamics. Existing environmental models encode extensive knowledge of individual systems, yet much of this information remains isolated within domain-specific formulations and data structures. This paper introduces a unified modeling framework that formalizes information from existing process models by asserting real-world physical relationships onto their underlying mathematical representations. By integrating Model-Based Systems Engineering (MBSE) with Hetero-functional Graph Theory (HFGT), the framework establishes a consistent ontology that explicitly defines system structure and behavior. Illustrative hydrological examples demonstrate implementation of the methodology, showing how relationships embedded in conventional process models can be made explicit and scalable. While simplified, these examples provide a first step toward applying the approach to complex environmental systems. More broadly, the methodology offers a foundation for future modeling of systems of systems within a shared computational architecture.