The NextGen Water Resources Modeling Framework: Community Innovation at the Intersection of Hydrologic, Data and Computer Sciences

Hydrologic science lacks a comprehensive theory of stormflow generation, preventing the development of a general hydrologic model. Studies show that models focusing on dominant local processes often outperform general models that rely on parameter tuning, leading to higher confidence solutions. For continental-scale hydrologic and hydraulic prediction, regional mosaics of models may outperform a single-model approach. However, variations in model inputs, programming languages, solvers, and discretizations hinder interoperability and comparisons. To address these challenges, we developed the Next Generation Water Resources Modeling Framework (NextGen): a model-agnostic, standards-based architecture for model interoperability and evaluation. Two standards enable the Framework: (1) the Basic Model Interface (BMI) version 2.0, for model control, coupling, and querying; and (2) the Open Geospatial Consortium WaterML 2.0 part 3 Hydrologic Features (HY_Features) conceptual data model to describe the “hydrofabric” of surface water hydrologic and hydraulic features. In the NextGen Framework, models retain their unique solution methods while becoming interoperable through BMI variable exchange tied to a common hydrofabric. The Framework enables scientific evaluation of water prediction models that simulate diverse hydrologic and hydraulic processes. Its design supports models written in multiple programming languages and runs on laptops, cloud and distributed memory supercomputers.