Water Models as Geographical Chimera: Precipitation Interception Routines as an Example of 'Patchwork Empiricism'

In constructing global 'water worlds', modellers stitch together data and theories from disparate locales, weaving them into seemingly universal hydrological frameworks. This approach offers immense scientific efficiencies, enabling planetary-scale predictions of water availability and related ecological, biogeochemical and atmospheric responses. As this paper shows, however, it risks creating 'geographical chimera’ of mismatched empirical parts where, for example, British leaves define rainwater storage, fresh-cut Idaho conifers define snow interception, and blotting‐paper bark substitutes for stem evaporation. Each localised study, once transplanted into a global model, can become disconnected from its site‐bound context, potentially distorting science, management actions, and policy. Focusing on forest canopy precipitation interception – the first step in the precipitation‐to‐discharge pathway – this paper reveals how (excellent) decades-old, narrowly framed experiments now anchor universal equations in cutting-edge land surface models. These inherited formulas and parameters risk obscuring local phenomena, devaluing in situ data, and fostering equifinality whereby different configurations yield similar outputs while masking real biophysical processes. In this paper, scientific review is complemented by philosophical critiques, reminding us that abstractions detached from place may become preserved in models through methodological inertia, forming self‐justifying 'mathematical mummies'. We need not abandon universality, but this work aims to reinforce the standing call to embed water models in diverse, site-grounded observations, re- examine entrenched analogies, and embrace pluralistic parameter development. A place-sensitive methodology can prevent 'chimeric’ routines from eclipsing the hydrological realities they aim to illuminate, enabling models to better reflect the richly varied planet they represent.