Data for Implementing BMI for the HBV Hydrological Model: A Case Study in NextGen Modeling Framework Integration

The Basic Model Interface (BMI) and Next Generation National Water Model (NextGen) framework have been developed to enable interoperability between distinct hydrologic models and model process components within large-scale (up to continental) modeling systems. This approach recognizes that no single model or component is universally optimal for all processes or locations. This paper explores the refactoring and wrapping of a hydrologic model and its components in BMI to be included in and support multi-model mosaics and models composed of compatible component modules. As a case study an R implementation of the Hydrologiska Byråns Vattenbalansavdelning (HBV) model was refactored and reimplemented in Python, a language supported by BMI, using Object-Oriented Programming (OOP) principles. The model was then wrapped with BMI functions, enabling its deployment in multi-model, mosaic-style modeling simulations. Each of the HBV’s four routines was further componentized into individual BMI-compliant components, resulting in reusable and importable modules. These components were successfully integrated into the NextGen framework to perform component-based hydrological simulations across multiple formulations. This work demonstrates the feasibility and benefits of using BMI to standardize the coupling of hydrological models and modularize their sub-components, ultimately fostering increased collaboration, reusability, and flexibility across modeling applications. It also provides a practical road map for converting a Python-based hydrological model into a BMI-compliant model component to promote model interoperability and reusability.