JGrass-NewAge is a modular hydrological modeling system using an object modeling system (OMS) infrastructure that allows for component-based construction of models in Java. It supports various hydrological tasks including discharge calculations, radiation assessment, and water tracer concentration computations, with an emphasis on modern and extensible hydrology. The system enables easy integration with existing software and provides tools for calibration and parallelization, making it adaptable for diverse hydrological studies.